Thermosets and Composites: Technical Information for Plastics Users

Thermosets and Composites Technical Information for Plastics Users, by M. Biron ISBN: 1856174115 Publisher: Elsevier Sc...

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Thermosets and Composites Technical Information for Plastics Users, by M. Biron

ISBN: 1856174115 Publisher: Elsevier Science & Technology Books Pub. Date: December 2003

List of Tables and Figures Tables Chapter 1 Table Table Table Table Table Table Table Table Table Table Table Table Table Table

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14

World consumption or production by weight (million tonnes) 2 World consumption or production in terms of volume (million m3) 3 World consumption at equal tensile stress (million m3 *Young's modulus) 3 Growth in world consumption- normalized on 100 for reference year 1985 4 4 Examples of material hardnesses 5 Tensile properties of various materials 7 Specific tensile properties of various materials 9 Physical and electrical properties of various materials 10 Thermal properties of various materials 12 Order of magnitude of some material costs (s 13 Order of magnitude of some material costs (s 15 [Tensile properties/cost per litre] ratios of various materials 26 Examples of the process choice versus the part characteristics 27 Examples of economic characteristics of some processes

Chapter 2 Table Table Table Table Table Table Table Table Table Table Table

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11

Table 2.12 Table 2.13 Table 2.14 Table 2.15 Table 2.16

Global plastic consumption 32 Market share for the major plastics 33 Market share for some engineering and speciality plastics 33 Annual consumption of major thermosets (1000 tonnes and %) 35 Composite consumption in North America, Europe and Asia 36 Market shares for the main matrices used for composites 37 Market shares for the seven main plastic application sectors 38 Market shares for the eight main thermoset application sectors 39 Market shares for the nine main composite application sectors 41 Market shares (%) for the main European countries 44 Europe: market shares (% by weight) for the nine main composite application sectors 45 Europe: market shares (% value) for the nine main composite application sectors 46 North America: market shares (%) for the nine main composite application sectors 47 Global consumption of major thermosets 1990-2005 (1000 tonnes and %) 48 Market shares and predicted growth for the nine main composite application sectors in the USA 49 Processing turnover statistics 50

Thermosets and Composites

Table Table Table Table

2.17 2.18 2.19 2.20

Table Table Table Table Table

2.21 2.22 2.23 2.24 2.25

Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table

2.26 2.27 2.28 2.29 2.30 2.31 2.32 2.33 2.34 2.35 2.36 2.37 2.38 2.39 2.40

Processing company and employment statistics 50 Comparative prices of resins and additives 52 Average selling prices of composites for different markets 54 Examples of mould prices (s and part costs expresse as the ratio [part price]/[raw composite price] 55 Automotive hood: unit cost (g) for prototypes and small outputs 55 Automotive hood: unit cost (g) for small and medium outputs 55 Automotive hood: unit cost (s for mass production 56 Processing methods for prototypes (relative cost per unit) 56 Processing methods for small and medium annual production (relative cost per unit) 56 Processing methods for high annual production (relative cost per unit) 56 Racing canoes: glass and aramid fibre comparison 57 Examples of prices for parts sold on catalogue 58 Examples of parts manufactured to order in small quantities: Unit costs 61 Weight reduction by composites 62 Automotive & transportation: Consumption of thermosets and composites 63 Furniture and bedding: polyurethane consumption in the USA 74 Polyurethane: US consumption in 2000 91 Unsaturated polyesters: shares in % per process (estimations) 95 Unsaturated polyester composites: shares in % per market (estimations) 96 Phenolic resins: shares in % per market (estimations) 104 Amino resin moulded parts: shares in % per market (estimations) 106 Epoxide resins: shares in % per market (estimations) 108 Silicones: shares in % per end use (estimations) 116 Silicones: shares in % per market (estimations) 116

Chapter 3 Table Table Table Table

3.1 3.2 3.3 3.4

Examples of UL temperature indices Examples of part tolerances for normal and precision classes Mechanical property examples for different glass reinforcements Some examples of Poisson's ratio

147 165 167 167

Chapter 4 Table 4.1 Table Table Table Table Table Table Table Table Table Table Table

XVIII

4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12

Polyurethanes: examples of property variations after immersion in ASTM C fuel for 72 h at 50~ Polyurethanes: chemical behaviour Characteristic examples of structural foams and dense polyurethanes Characteristic comparison of various polyurethane foams Castable polyurethanes: property examples RIM elastomer polyurethanes: examples of properties RIM structural foam polyurethanes: examples of properties Rigid polyurethane foams: examples of properties Semi-rigid polyurethane foams: examples of properties Flexible polyurethane foams: examples of properties Polyurea properties: examples Unsaturated polyester: performance retention after immersion in hot water

190 191 195 195 197 199 200 201 201 202 203 214

Contents

Table 4.13 Table 4.14 Table 4.15 Table Table Table Table

4.16 4.17 4.18 4.19

Table 4.20 Table 4.21 Table 4.22 Table 4.23 Table 4.24 Table 4.25 Table 4.26 Table 4.27 Table 4.28 Table 4.29 Table 4.30 Table 4.31 Table 4.32 Table 4.33 Table 4.34 Table 4.35 Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table Table

4.36 4.37 4.38 4.39 4.40 4.41 4.42 4.43 4.44 4.45 4.46 4.47 4.48 4.49 4.50 4.51 4.52 4.53

Unsaturated polyester unreinforced resins for casting and moulding, matrices for composites: examples of resin properties 217 Vinylester neat resins for casting and moulding, matrices for composites: examples of resin properties 218 Filled or short fibre reinforced unsaturated polyesters (UP): examples of resin properties 219 Fire retardant vinylester resins: examples of resin properties 219 Unsaturated polyester BMC: examples of composite properties 220 Unsaturated polyester SMC: examples of composite properties 220 Other glass fibre reinforced unsaturated polyesters: examples of composite properties 222 Aramid and carbon fibre reinforced acrylate urethane: examples of composite properties 223 Examples of characteristics of certain phenolic moulding powders after ISO 800 224 Designation examples of some phenolic moulding powders after ISO 800 224 Examples of phenolic resin chemical behaviour at room temperature 231 Examples of glass fibre reinforced phenolic moulding powders 235 Examples of mineral filled phenolic moulding powders 237 Examples of organic filled phenolic moulding powders 237 Examples of tribological phenolic moulding powders (after Vynco) 238 Glass fibre reinforced phenolic SMC and BMC: examples of properties 239 Phenolic foam: examples of properties 239 Melamines: chemical behaviour examples 244 Melamine foams: characteristic examples 246 Melamines: characteristic examples 247 Phenolic modified melamines: Characteristic examples 249 Filled unsaturated polyester modified melamines: characteristic examples 250 V0 cellulose filled urea-formaldehyde moulding powder: characteristic examples 250 Epoxies: examples of chemical behaviour at room temperature 261 Examples of moulding and cast epoxides: general properties 268 Examples of epoxide matrices for composites: general properties 269 Examples of filled and reinforced moulding epoxides: general properties 270 Examples of unidirectional epoxide composites: general properties 272 Examples of epoxide composites: general properties 273 Examples of foamed epoxides: general properties 274 Examples of epoxide syntactic foams: general properties 275 Polyimides: examples of tribological properties 281 Polyimides: examples of chemical behaviour at room temperature 285 Thermoset polyimides for moulding: property examples 291 Condensation polyimides for moulding: property examples 293 Undefined polyimides for moulding: property examples 295 Polyimides for laminates: property examples 296 Polyimide foams: property examples 297 Polyimide films: property examples 297 Silicones and fluorosilicones: examples of chemical behaviour 306 Silicone foam: property examples 310 XIX


Table Table Table Table Table Table Table Table Table Table Table Table Table

4.54 4.55 4.56 4.57 4.58 4.59 4.60 4.61 4.62 4.63 4.64 4.65 4.66

Silicone resins for electronics and optics: property examples Glass fibre reinforced silicone resin laminates: property examples HVR silicones: Property examples LSR silicones: property examples RTV silicones: property examples Silicone elastomers for electronics Silicone foams: property examples Fluorosilicone resins for optics: property examples Fluorosilicone elastomers: property examples Polycyanate syntactic foams: property examples Polycyanate composites: property examples Neat polycyanates: property examples Dicyclopentadiene: property examples

311 312 312 313 314 315 315 315 316 321 321 322 325

Chapter 6 Table 6.1 Table 6.2 Table 6.3 Table 6.4 Table 6.5 Table 6.6 Table 6.7 Table 6.8 Table 6.9 Table 6.10 Table 6.11 Table Table Table Table

6.12 6.13 6.14 6.15

Table Table Table Table Table Table Table Table Table

6.16 6.17 6.18 6.19 6.20 6.21 6.22 6.23 6.24

XX

Examples of the suggested process choice versus the part characteristics 345 Examples of epoxy composite properties versus hardener and cure processing 352 Suggestions for the choice of processes versus thermoset nature 357 Example properties for composites with two reinforcements: matrix effects 370 Average composition and main property examples of the three main types of glass fibres used in polymer reinforcement 374 Typical mechanical and physical properties of various glass fibres 375 Examples of reinforcement ratios based on tensile strength and modulus of various reinforced polymers 376 Examples properties of various carbon fibres 379 Examples of reinforcement ratios of CFRP and enhancement ratios versus GFRP 381 Example properties of various aramid fibres 382 Examples of enhancement ratios obtained with incorporation of aramid fibres instead of glass fibres in a composite 383 Characteristic comparison examples of the three main fibres 383 Properties of some sustainable fibres compared to glass fibres 385 Example properties of various fibres 388 Example properties of a 60% glass fibre reinforced resin for different fibre forms 389 Example properties of PVC foams 391 Example properties for polystyrene foams 393 Example properties for polyurethane foams 393 Example properties for polyethylene foams 394 Example properties for polypropylene foams 395 Example properties for polymethacrylimide foams 396 Examples of properties of polyetherimide foam 397 Some typical properties of high performance syntactic foams 398 Examples of properties of polyethersulfone foams 398

Contents

Table 6.51 Table 6.52 Table 6.53

Property examples for polyamide nanocomposites processed by various methods 403 Property examples of a 2% nanosilicate filled polyamide 404 Property examples for various intermediate semi-manufactured thermoset and thermoplastic composites 411 Examples of self-reinforced polypropylene properties compared to other general-purpose solutions 413 Classification of the main reinforcement possibilities 444 Property examples of the same thermoplastic reinforced with the same level of the three main reinforcement fibres 445 Examples of nanocomposite properties 445 Property examples of short glass fibre reinforced plastics 446 Property examples of the same thermoplastic reinforced with increasing levels of the same short glass fibre 446 Property examples of the same thermoplastic (PA) reinforced with increasing levels of carbon fibres 447 Basic property example of short carbon fibre reinforced thermoplastics 448 Basic property examples of short aramid, glass and carbon fibre reinforced polyamide 449 Basic property examples of long glass fibre reinforced polyamides and polypropylenes 450 Basic property examples of long glass fibre reinforced BMCs 451 Basic property examples of glass fibre reinforced SMCs 452 Basic property examples of carbon fibre reinforced SMCs with epoxy matrix 453 Basic property examples of glass mat reinforced unsaturated polyesters 453 Basic property examples of glass mat thermoplastics (GMT) 454 Basic property examples of glass fabric and roving reinforced composites 455 Basic property examples of glass mat thermoplastics (GMT) 455 Basic property examples of carbon fabric reinforced acrylate urethane (unsaturated polyester) 456 Property examples of thermoplastic prepregs 456 Basic property examples of aramid reinforced acrylate urethane (unsaturated polyester) 457 Basic property examples of aramid reinforced UD epoxy composite in the fibre direction 457 Flexural modulus and maximum load examples for sandwich composites 458 Basic property examples of carbon reinforced UD epoxy and polyimide composites 458 Property examples of RRIM and SRRIM composites 459 Property examples of composites made of reinforced foamed matrices 460 Property examples of RRIM and SRRIM composites 460

Chapter 7 Table 7.1 Table 7.2 Table 7.3 Table 7.4 Table 7.5

Property examples of epoxy syntactic foams Examples of smoke emission for selected plastics Examples properties of conductive and neat plastics Selected properties example of fire-proofed epoxy and hybrid composite Annual growth (%) in major thermoset and composite consumption

Table 6.25 Table 6.26 Table 6.27 Table 6.28 Table 6.29 Table 6.30 Table 6.31 Table 6.32 Table 6.33 Table 6.34 Table 6.35 Table 6.36 Table 6.37 Table 6.38 Table 6.39 Table 6.40 Table Table Table Table Table

6.41 6.42 6.43 6.44 6.45


465 465 466 466 472 xxI



Property examples of BMC and glass fibre reinforced polyamide Processing and end-of-life scraps of glass reinforced polypropylene: property retention versus the number of recycling cycles Property retention (%) of BMC/SMC and polypropylene versus the level of BMC recyclate Comparison of the calorific properties of coal and plastic waste fuels Examples of properties of "extruded or injected woods" compared to PVC

479 488 489 489 491

Figures Chapter 1 Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16

World consumption evolutions - base 100 in 1985 Hardness of some materials Tensile strength (MPa) of various materials Tensile modulus (GPa) of various materials Specific tensile strength (MPa) of various materials Specific tensile modulus (GPa) of various materials Examples of fatigue failure Examples of material costs s Examples of material costs s Examples of ratios "Tensile strength versus costs per litre" Examples of ratios "Tensile modulus versus costs per litre" Thermoset before crosslinking or thermoplastic Thermoset after crosslinking Pyramid of excellence for some thermoset families Pyramid of excellence for some composite families Selection scheme of the material and process

4 5 6 6 8 8 11 13 14 15 15 16 16 17 19 30

World plastic consumption - Million tons Market shares based in the whole thermoset consumption Market shares based in the whole plastic consumption Market shares of the 3 main regions of composite consumption % Market shares of the 3 main composite matrixes Market shares of the 7 major plastic application sectors Market shares of the 8 major thermoset application sectors Market shares of the 9 major composite application sectors Market shares of the main thermoplastic processings Market shares of the main thermoset processings Market shares of the main composite processings Composite market shares in European countries Composite market shares for the main applications in Europe Composite market shares for the main applications in America End-life cost of the plastic parts Plastic raw materials: costs e per litre Additive panel Relative costs of various fibre reinforcements

32 35 36 37 38 39 40 41 42 43 43 45 46 48 50 51 52 53

Chapter 2 Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. XXII

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18

Contents

Fig. 2.19 Fig. 2.20 Fig. 2.21

Relative costs of various cores for sandwich composites Overspending of composites versus metal and ArF or CF composites versus GF ones Overcost of the CF composite versus GF ones

53 60 60

Chapter 3 Fig. 3.1 Fig. 3.2 Fig. 3.3 Fig. 3.4 Fig. 3.5 Fig. 3.6 Fig. 3.7 Fig. 3.8 Fig. 3.9 Fig. 3.10 Fig. 3.11 Fig. 3.12 Fig. 3.13 Fig. 3.14 Fig. 3.15

Tensile behaviour of polymers Continuous use temperature examples, ~ HDT A examples, ~ Density examples, g/cm3 Tensile strength examples, MPa Elongation at break examples % Flexural strength examples, MPa Flexural Modulus examples, GPa Compression strength examples, MPa Notched impact strength examples, Index without unit Heat modulus retention examples, % Fatigue examples, Index without unit versus cycle numbers Resistivity examples, loglo(ohm cm) Dielectric rigidity examples, kV/mm Dielectric loss factor examples, 10-4

149 168 169 170 171 172 173 174 175 176 177 178 179 180 181

Chapter 4 Fig. 4.1 Fig. 4.2 Fig. 4.3 Fig. 4.4 Fig. 4.5 Fig. 4.6 Fig. 4.7 Fig. 4.8 Fig. 4.9 Fig. 4.10 Fig. 4.11 Fig. 4.12 Fig. 4.13 Fig. 4.14 Fig. 4.15

Polyurethane: Ageing for 7 days. Tensile strength retention versus temperature of ageing Polyurethane: Ageing for 7 days. Elongation at break retention versus temperature of ageing Polyurethane: examples of tensile strength retention versus immersion time in hot water Examples of polyurethane foams: tensile strength versus density Vinylester composites. Tensile modulus retention versus testing temperature Vinylester composite (A) ageing at 160, 182, 204 ~ Examples of flexural strength retention versus time (month) Vinylester composite (B) ageing at 160, 182, 204 ~ Examples of flexural strength retention versus ageing time (month) Unsatured polyester. Tensile strength versus % and length of fibres Unsatured polyester. Tensile modulus versus % and length of fibres Unsatured polyester: Examples of creep deflection (mm) versus testing time (hours) Unsatured polyester. Notched impact versus % and length of fibres Unsatured polyester: Examples of endurance strengths versus the number of cycles in water Example of phenolic BMC ageing at 150 ~ up to 225 ~ Tensile retention versus time Example of ageing of two phenolic BMC: Modulus retention versus time at 225 ~ Glass fibre reinforced melamine: example of modulus retention versus temperature

188 188 190 194 209 210 210 211 211 212 212 213 229 229 242 XXIII


Fig. 4.16 Fig. Fig. Fig. Fig.

4.17 4.18 4.19 4.20

Fig. 4.21 Fig. 4.22 Fig. 4.23 Fig. 4.24 Fig. 4.25 Fig. 4.26 Fig. 4.27 Fig. 4.28 Fig. 4.29 Fig. 4.30 Fig. Fig. Fig. Fig.

4.31 4.32 4.33 4.34

Heat resistant epoxide: example of lifespan for 70% flexural strength rentention versus temperature 256 Epoxide: example of LN(half-life in days) versus 1000/T en ~ 256 Epoxide: example of creep versus time at 20 ~ and 80 ~ 258 Epoxide: example of creep modulus versus time at 23 ~ and 85 ~ 258 Epoxide dynamic fatigue: examples of SN curves. Maximum stress versus cycle numbers 259 Glass fabric reinforced epoxy composite: Example of dynamic fatigue: SN curves, maximum stress versus cycle numbers 260 Polyimides: Examples of flexural modulus retention versus temperature 279 Polyimides: Examples of half-life versus temperature 280 Polyimides: Examples of coefficient of friction versus temperature 281 Polyimides: Examples of creep modulus (MPa) versus time (hours) 282 Polyimides: Examples of lineic dimensional variation versus time (days) 282 Polyimides: Two examples of SN curves maximum stress (MPa) versus loading cycle number 283 Dynamic fatigue of polyimide: Two examples of maximum stress (MPa) versus temperature 283 Polyimide: Tensile strength and elongation retentions versus WeatherOmeter exposure time (h) 284 Silicone: Examples of tensile strength and elongation at break retentions versus temperature 302 Silicone: Examples of half-life versus temperature 303 Silicone: Examples of compression sets versus time 305 Polycyanates: Examples of tensile strength versus water content 319 Polycyanates: Examples of glass transition temperature versus water content 319

Chapter 5 Fig. Fig. Fig. Fig. Fig. Fig. Fig.

5.1 5.2 5.3 5.4 5.5 5.6 5.7

Thermoset processing methods Principle of the compression moulding Principle of the compression transfer moulding Principle of the high-pressure injection moulding Principle of the extrusion Principle of the RIM: Resin Injection Moulding Principle of the rotational moulding of a cylindrical tank

330 331 333 334 335 337 338

Chapter 6 Fig. Fig. Fig. Fig.

6.1 6.2 6.3 6.4

Fig. Fig. Fig. Fig. Fig.

6.5 6.6 6.7 6.8 6.9

XXIV

Schematic curve of a performance versus fibre length 347 Thermoset matrices: Examples of mechanical properties 356 Thermoset matrices: Examples of thermal properties 356 Neat thermoplastic matrices: Examples of continuous use temperatures at unstressed state 366 Neat thermoplastic matrices: Examples of HDT A (1.8 MPa), ~ 367 Neat thermoplastic matrices: Examples of tensile modulus, GPa 368 Neat thermoplastic matrices: Examples of tensile strength, MPa 369 Fibres: Examples of tensile strength versus modulus 371 Fibres: Examples of reinforcement ratios for short glass fibre reinforced PA6 372

Contents

Fig. 6.10 Fig. 6.11 Fig. 6.12 Fig. 6.13 Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.

6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 6.22

Fig. 6.23 Fig. 6.24 Fig. Fig. Fig. Fig. Fig.

6.25 6.26 6.27 6.28 6.29

Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.

6.30 6.31 6.32 6.33 6.34 6.35 6.36 6.37 6.38 6.39 6.40 6.41 6.42

Ratios [Costs of short glass fibre reinforced thermoplastics/neat thermoplastics] versus costs of the neat grades 377 Glass, aramid, carbon fibre reinforced composites: Tensile modulus versus tensile strength examples 384 Schematic principle of a sandwich composite with foamed core 390 Example of sandwich panel made from an extruded polypropylene honeycomb core 399 Sandwich structure examples: Flexural strength versus density 401 Schematic structure of nanofillers 402 Sandwich structure examples: Flexural modulus versus density 402 Schematic structures of nanocomposites 403 Schematic manufacturing of SMC 405 Example of the effect of glass fibre level on flexural modulus 406 Example of the effect of glass fibre level on flexural strength 407 Example of the effect of glass fibre level on impact strength 407 Polypropylene GMT examples: Thermal and mechanical property examples 409 Polyester GMT examples: Thermal and mechanical property examples 410 Examples of various intermediate semi-manufactured composites: Modulus versus strength 412 Principle of the hand lay-up moulding 415 Principle of the vacuum bag moulding after hand or spray lay-up 417 Principle of the pressure bag moulding after hand or spray lay-up 418 Principle of the press moulding after hand lay-up or spray lay-up 419 Principle of the SRRIM: Structural Reinforced Resin Injection Moulding 421 Principle of the infusion process 422 Principle of the VARI - Vacuum Assisted Resin Injection 424 Principle of the compression transfer moulding 426 Principle of the high-pressure injection moulding 427 Principle of an automated tape placement machine 428 Principle of the filament winding 430 Principle of the pultrusion 431 Principle of the pullwinding 432 Schematic continuous sheeting 433 Principle of the stamping 435 Principle of the composite insert moulding 436 Principle of the extrusion-compression process 437 Principle of the sandwich structure 438

Chapter 7 Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8

Laws and requirements of the market Design diagram Project diagram Thermoset types: Recent patents for a same period Fibre types: Recent patents for a same period Nanoreinforcements: Recent patents Structures and processes: Recent patents The waste collect and pretreatment

466 468 469 482 483 483 484 486 xxv

Disclaimer

All the information contained in this work was collected from reliable documentation and verified as far as possible. However, we cannot accept responsibility for the accuracy of the data. The characteristic data and economic figures are not guaranteed and cannot be used for calculations, computations or other operations to determine design, cost-effectiveness or profitability. The reader must verify the technical data and economic figures with his own suppliers of raw materials or parts, and other current technical and economic sources.

Acronyms and abbreviations 5V

UL fire rating

ABS

Acrylonitrile-Butadiene-Styrene

AMC

Alkyd Moulding Compound

ArF or AF

Aramid Fibre

ASA

Acrylonitrile Styrene Acrylate

ASTM

American Society for Testing and Materials

ATH

Aluminium TriHydrate

BF

Boron Fibre

BMC

Bulk Moulding Compound

BMI

BisMalelmide

CA

Cellulose Acetate

CAB

Cellulose AcetoButyrate

CAD

Computer Aided Design

CE

Cyanate Ester

CF

Carbon Fibre

CFC

ChloroFluoroCarbon

CIC

Continuous Impregnated Compound

CNT

Carbon NanoTube

CONC

Concentrated solution

COPE

COPolyEster TPE

CS

Compression Set

CUT

Continuous Use Temperature under unstressed state

Cy

PolyCyanate

DAP

DiAllyl Phthalate

DCPD

Poly(DicycloPentaDiene)

DMC

Dough Moulding Compound

DRIV

Direct Resin Injection and Venting

DSC

Differential Scanning Calorimeter


EB

Elongation at Break

EE

Electricity & Electronics

EMI

ElectroMagnetic Interference

EP

EPoxy

ESC

Environmental Stress Cracking

ESD

ElectroStatic Discharge

ETFE

Ethylene-TetraFluoroEthylene

FEP

Fluorinated Ethylene Propylene

FR

Fire Retardant

GF

Glass Fibre

GMT

Glass Mat Thermoplastic

HB

UL fire rating

HDT

Heat Deflection Temperature

HPGF

High Performance short Glass Fibre reinforced polypropylene

HSCT

High Speed Civil Transport (aircraft)

HTPC

Hybrid ThermoPlastic Composite

HTV

High Temperature Vulcanization

ILSS

InterLaminar Shear Strength

IMC

In Mould Coating

IPN

Interpenetrating Polymer Network

IRHD

International Rubber Hardness

IRM

International Referee Material

ISO

International Standardisation Organisation

LCP

Liquid Crystal Polymer

LCTC

Low Cost Tooling for Composites

LDPE

Low Density PolyEthylene

LEFM

Linear Elastic Fracture Mechanics

LFRT

Long Fibre Reinforced Thermoplastic

LFT

Long Fibre reinforced Thermoplastic

LGF

Long Glass Fibre

LIM

Liquid Injection Moulding

LRTM

Light RTM

LSR

Liquid Silicone Rubber

LWRT

Low Weight Reinforced Thermoplastic

XXX

Acronyms and abbreviations

MF

Melamine

O&M

Organisation & Methods department

PA

PolyAmide

PAI

PolyAmide Imide

PAN

PolyAcryloNitrile

PBI

PolyBenzImidazole

PBT

PolyButyleneTerephthalate

PC

PolyCarbonate

PCL

PolyCaproLactone

PCTFE

PolyChloroTriFluoroEthylene

PE

PolyEthylene

PEAR

PolyEtherAmide Resin

PEBA

PolyEther Bloc Amide

PEEK

PolyEtherEther Ketone

PEG

PolyEthylene Glycol

PEI

PolyEtherImide

PEK

PolyEtherKetone

PES or PESU

PolyEtherSulfone

PET

PolyEthylene Terephthalate

PETI

PhenylEthynyl with Imide Terminations

PF

Phenolic resin

PF1Ax

PF general purpose, ammonia free

PF2Cx

PF heat resistant, glass fibre reinforced

PF2Dx

PF impact resistant, cotton filled

PF2E1

PF mica filled

PFA

PerFluoroAlkoxy

PGA

PolyGlycolic Acid

PHA

PolyHydroxyAlkanoate

PHB

PolyHydroxyButyrate

PI

PolyImide

PLA

PolyLactic Acid

PMI

PolyMethacrylImide

PMMA

PolyMethylMethAcrylate

POM

PolyOxyMethylene or Polyacetal XXXI


PP

PolyPropylene

PPE

PolyPhenylene Ether

PPO

PolyPhenylene Oxide

PPS

PolyPhenylene Sulfide

PPSU

PolyPhenyleneSulfone

Prepreg

Preimpregnated

PS

PolyStyrene

PSU

PolySulfone

PTFE

PolyTetraFluoroEthylene

PUR

PolyURethane

PV

Pressure*Velocity

PVA

PolyVinyl Alcohol

PVC

PolyVinyl Chloride

PVDF

PolyVinyliDene Fluoride

PVF

Polyvinyl Fluoride

RF

RadioFrequency

RFI

Resin Film Impregnation

RH

Relative Humidity or Hygrometry

RIM

Reaction Injection Moulding

RIRM

Resin Injection Recirculation Moulding

RP

Reinforced Plastic

RRIM

Reinforced Reaction Injection Moulding

RT

Room Temperature

RTM

Resin Transfer Moulding

RTP

Reinforced ThermoPlastic

RTV

Room Temperature Vulcanization

SAN

Styrene AcryloNitrile

SATUR

Saturated solution

SB

Styrene Butadiene

SCRIMP

Seeman's Composite Resin Infusion Moulding Process

Si

Silicone

SMA

Styrene Maleic Anhydride

SMC

Sheet Moulding Compound

SN curve

Plot of stress or strain (S) leading to the failure after N cycles of repeated loading

XXXII

Acronyms and abbreviations

SOL

Solution

SP-polyimides

Condensation polyimides

SRRIM

Structural Reinforced Resin Injection Moulding

TAC

TriAllyl Cyanurate

TDI

Toluene-2,4-Dilsocyanate

TFE

TetraFluoroEthylene

TGA

ThermoGravimetric Analysis

TGV

High speed train

TMC

Thick Moulding Compound

TP

ThermoPlastic

TPE

ThermoPlastic Elastomer

TPU

ThermoPlastic polyUrethane

TR

Temperature-Retraction procedure

TS

Tensile Strength

UD

UniDirectional composite

UF

Urea-Formaldehyde

UL

Underwriters Laboratories

Unkn.

Unknown

UP

Unsaturated Polyester

UV

UltraViolet

V0 to V2

UL fire rating

VARI

Vacuum Assisted Resin Injection

VARTM

Vacuum Assisted RTM

VE

VinylEster

VIP

Vacuum Infusion Process

VST

Vicat Softening Temperature

ZMC

a highly automated process using Moulding Compounds

XXXIII

Table of Contents

List of tables and figures Disclaimer Acronyms and abbreviations Ch. 1

Outline of the actual situation of plastics compared to conventional materials

Ch. 2

The plastics industry: economic overview

Ch. 3

Basic criteria for the selection of thermosets

Ch. 4

Detailed accounts of thermoset resins for moulding and composite matrices

Ch. 5

Thermoset processing

Ch. 6

Composites

Ch. 7

Future prospects for thermosets and composites Conclusion Index

Chapter 1

Outline of the actual situation

of plastics compared to conventional materials


No engineer or designer can be ignorant of plastics, but the decision to use a new material is difficult and important. It has both technical and economical consequences. It is essential to consider: 9 The actual penetration of the material category in the industrial area 9 The abundance or scarcity of the material and the process targeted 9 The functionalities of the device to be designed 9 The characteristics of the competing materials 9 The cost 9 The processing possibilities 9 The environmental constraints. The goal of the facts and figures that follow is to help clarify quickly the real applications for thermosets and composites and the relative importance of the various material families and processes involved.

1.1 Polymers: the industrial and economic reality compared to traditional materials 1.1.1 Plastic and metal consumption

Usually, material consumption is considered in terms of weight (Table 1.1), but it is also interesting to examine: 9 The consumption or production in terms of volume (Table 1.2), which is the most important for fixed part sizes. 9 The consumption linked to the rigidity of the engineering materials (Table 1.3). In this last case, if the reference material, of unitary section area and unitary length, is M0 (volume V0 = 1) with Young's modulus E0, it can be

Table 1.1 World consumption or production by weight (million tonnes) Year

Plastic

Sted

A~minium

1970

30

595

10

1975

40

644

13

1980

48

716

16

1985

68

719

17

1990

92

770

19

1995

122

752

20

2000

147

848

24


Table 1.2

World consumption or production in terms of volume (million m 3) Year

Plastic

Steel

A~minium

1970

30

76

4

1975

40

82

5

1980

48

92

6

1985

68

92

6

1990

92

99

7

1995

122

96

7

2000

147

109

9

Table 1.3

World consumption at equal tensile stress (million m3*Young's modulus) Year

Plastic

Steel

A~minium

1970

60

15 000

300

1975

80

16 000

375

1980

96

18 000

450

1985

136

18 000

450

1990

184

20000

525

1995

244

19 000

525

2000

297

21 000

675

replaced with material M1 with unitary length, section area S1, and Young's modulus E l . For the same tensile stress: SI*E1 = l ' E 0 So: $1 = E0/E1 The volume of M1 with the same rigidity as M0 is: V1 = $1"1

= V0*E0/E1

therefore: V I * E 1 = V0*E0 Table 1.3 compares the rigidity-modified data for consumption. expressed as volume (million m 3) * Young's modulus (GPa). The tensile modulus is arbitrarily fixed at 2 for plastics, 200 for steel and 75 for aluminium. The annual consumption of plastics is: 9 Intermediate between those of steel and aluminium in terms of weight, that is, roughly a sixth of the consumption of steel and six times the consumption of aluminium for recent years. 9 Higher than those of steel and aluminium in terms of volume in recent years: roughly 1.4 times the consumption of steel and 16 times that of aluminium.


9

Lower than those of steel and aluminium if we reason in terms of equal rigidity: plastic consumption is equivalent to roughly 1% of the steel consumption and half that of aluminium. The average annual growth rate over the past 30 years is: 9 5 . 5 % for plastics 9 1.1% for steel. Over the 15 years from 1985 to 2000, the average annual growth rates are confirmed for plastics and steel (Table 1.4). The polymer composites also show a progression exceeding that of metals. Figure 1.1 displays these normalized changes in world consumption. Table 1.4

Growth in world consumption - normalized on 100 for reference year 1985

Plastics

Composites

Aluminium

Steel

1985

100

100

100

100

1990

135

150

112

107

1995

179

160

118

104

2000

216

190

141

115

Figure 1.1.

World consumption evolutions - base 100 in 1985

1.1.2 Mechanical properties 1.1.2.1. Intrinsic mechanical properties

Expressed in the same Vickers unit, the hardnesses of the engineering materials cover a vast range, broader than 1 to 100. The handful of example figures in Table 1.5 do not cover the hardnesses of rubbers, alveolar polymers and flexible thermoplastics... Table 1.5

Hardness

Examples of material hardnesses

Aluminium

PMMA

Steel

Tungsten

15

22

150

350

Glass 540

Tungstencarbide 2400


Figure 1.2 visualizes the hardnesses of a broad range of materials. Table 1.6 indicates the tensile characteristics of some traditional materials (metals, glass, wood) and polymers in various forms:

Figure 1.2. Table 1.6

Hardness of some materials Tensile properties of various materials

Tensile strength, MPa YieM stress, MPa Metals & alloys Min. Max. Min. Max. Steel Titanium Aluminium Magnesium

300 1000 75 85

Bulk glass Fibre glass

40 2000

1800 1000 700 255

200

1700

30 43

550 190

Tensile modulus, GPa

210 105 75 44

Glass 300 3500

55-85

Wood Wood

5

16

11

Polymer composites Unidirectional CF Unidirectional A r F Unidirectional G F SMC CF SMC GF

1800 1400 800 280 48

3000 1500 800 350 285

260 87 28 50 21

Long glassfibre reinforcedpolymers EP LGF

90

90

16

Short glassfibre reinforcedpolymers EP GF & Mineral P E E K 30% CF P E E K 30% GF

50 210 165

100 210 165

14 17 10

Neatpolymers PEEK Epoxy

80 70

90

4 4

Foamed polymers Expanded & foamed plastics 0.05 16 0.02-0.5 ArF: aramid fibre; CF: c a r b o n fibre; GF: glass fibre; L G F : long glass fibre; U D : unidirectional.


9

Unidirectionalcomposites, highly anisotropic.

9

S M C , 2 D quasi-isotropic.

9

LFRT, more or less quasi-isotropic.

9

Short fibre reinforced plastics, 3D isotropic.

9

Neat polymers, 3D isotropic.

9

Alveolar polymers.

The indicated figures are examples and do not constitute exhaustive ranges. Figures 1.3 and 1.4 show that: 9

Unidirectional composites in the fibre direction can c o m p e t e with existing metals and alloys. H o w e v e r , it is necessary to m o d e r a t e this good classification by taking account of these composites' high anisotropy, with low resistance and m o d u l u s in the direction p e r p e n d i c u l a r to the fibres.

9

The h i g h e s t - p e r f o r m a n c e engineering m a g n e s i u m and a l u m i n i u m alloys.

plastics

compete

with

Wood Engineering plastics _

Glass Other composites, UD perpendicular fibre Current metals & alloys _

UD Composites fibre direction l

I

l

10

100

1000

, MPa

10000

Figure 1.3. Tensile strength (MPa) of various materials

Wood Engineering plastics Other composites & UD perpendicular fibre UD Composites fibre direction Current metals & alloys !

10 Figure 1.4. Tensile modulus (GPa) of various materials

!

100

,GPa 1000


1.1.2.2. Specific mechanical properties

The specific mechanical properties take account of the density and consider the performance to density ratio: [performance/density]. Due to the high densities of metals, the resulting classification (Table 1.7 and Figures 1.5 and 1.6) is different from that for the mechanical properties alone. Table 1.7

Specific tensile properties of various materials

Density

Specific tensile strength, MPa

Specific tensile modulus, GPa

Metals & alloys Min.

Max.

Steel

7.8

38

231

Titanium

4.5

220

222

23

Aluminium

2.8

27

250

27

Magnesium

1.75

49

146

25

16

120

12

21

27

Glass 2.5

Wood 0.4-0.75

13-27

Polymer composites Unidirectional CF

1.56

1154

1923

167

Unidirectional A r F

1.37

1022

1095

64

Unidirectional G F

1.9

421

421

15

SMC CF

1.5

187

233

33

SMC GF

1.8

27

158

3-12

50

9

Long glassfibre reinforcedpolymers EP L G F

1.8

50

Short glassfibre reinforcedpolymers EP G F & mineral

1.9

26

53

5-9

P E E K 30% CF

1.44

146

146

12

P E E K 30% GF

1.52

109

109

7

PEEK

1.3

62

62

3

Epoxy

1.2

58

75

3

2

17

0.4-0.6

Neat polymers

Foamed polymers Expanded & foamed plastics

0.02-0.9

ArF: aramid fibre; CF: c a r b o n fibre; GF: glass fibre; L G F : long glass fibre; U D : unidirectional.


Wood Glass Engineering plastics Other composites, UD perpendicular fibre Current metals & alloys UD Composites fibre direction !

1

!

10

100

i

MPa

'

1000

1000(

Figure 1.5. Specific tensile strength (MPa) of various materials

Engineering plastics Other composites & UD perpendicular fibre

m

Wood

m

Current metals & alloys UD Composites fibre direction

!

1

10

GPa

100

100C

Figure 1.6. Specific tensile modulus (GPa) of various materials

The graphs in Figures 1.5 and 1.6 show that: 9 Unidirectional composites in the fibre direction can compete with existing metals and alloys and some have the highest performances. However, it is necessary to moderate this good classification by taking account of their high anisotropy with low resistance and modulus in the direction perpendicular to the fibres. 9 The best of the other engineering plastics cannot match the high performance of the magnesium and aluminium alloys in terms of rigidity. 1.1.3 Thermal and electrical properties

Metals are characterized by their low coefficients of thermal expansion and their strong thermal and electric conductivities, whereas wood (except where there is excessive moisture), glass and polymers have high coefficients of thermal expansion and are electrical and thermal insulators. The loading or reinforcement of the polymers changes these characteristics:


9

The coefficients of thermal expansion decrease.

9

Carbon fibres, steel fibres, carbon blacks lead to more or less conducting polymer grades.

Table 1.8 displays some thermal and electrical characteristics of polymers and conventional materials. Table 1.8

Physical and electrical properties of various materials

Coefficients of thermal expansion, l ~Y6

Thermal conductivity, W/m.K

Electricalresistivity, loglo

Metals & alloys Copper

16-20

115-394

-7 to -8

Aluminium

20-25

237

-7 t o - 8

1.2

12-15

Glass 8.8

Wood 0.1-0.2

5: high hygrometry 8: for 12% moisture

Polymer composites Unidirectional CF Fibre direction

-0.04

50

38

1

Fibre direction

12

0.4

11-15

Perpendicular to the fibre direction

22

0.2

11-15

Perpendicular to the fibre direction Unidirectional GF

SMC CF

3

SMC GF

11-20

11

Short fibre reinforcedpolymers Epoxy CF

3-12

0.6-1.1

EP GF

12-20

0.6-1.2

P E E K 30% CF

15-40

0.9

5

P E E K 30% GF

15-20

0.4

15

14

Neat polymers Epoxy

60

0.2

15

PEEK

40-60

0.25

16

Foamed polymers Plastics

0.025-0.120

ArF: aramid fibre; CF: carbon fibre; GF: glass fibre; L G F : long glass fibre; U D : unidirectional.


1.1.4 Durability

Metals and glass generally support higher temperatures than polymers, which present a more or less plastic behaviour under stresses, leading to: 9 An instant reduction of the modulus and ultimate strength. 9 A long-term creep or relaxation. Polymers are sensitive to thermo-oxidation and, for some, to moisture degradation. The other polymers, unlike current steels, are not sensitive to corrosion. Table 1.9 displays some thermal characteristics of polymer and conventional materials. Metals have minimum melting points higher than 400 ~ and often higher than 1000 ~ whereas: 9 Thermosets because of the crosslinking cannot melt but decompose without melting as the temperature increases. 9 Thermoplastics melt in the range of 120 ~ for polyethylene to 350 ~ for high-performance thermoplastics.

Table 1.9

Thermal properties of various materials

Melting point (~

Long-term resistance temperature under unstressed s t a t e (~

Heat deflection temperature, HD T 1.8 MPa ( ~C)

Metals Iron

1535

Aluminium

1660

Magnesium

649

Polymer composites UD EP/CF

Non-fusible

150-230

UD E P / G F

Non-fusible

150-230

SMC E P / G F

Non-fusible

130-230

290

Short fibre reinforced polymers EP/CF

Non-fusible

130-230

EP/GF

Non-fusible

130-230

290

P E E K 30 CF

334

250

320

P E E K 30 G F

334

250

Neatpolymers Epoxy

Non-fusible

130-230

PEEK

334

250

10

150


The thermal behaviour of the polymers can be characterized: 9 Immediately, by the H D T (heat deflection temperature) under a 1.8 MPa load. For the chosen examples, the values vary between 150 ~ and 320 ~ In the long term, by the CUT (continuous use temperature) in an unstressed state. For the examples chosen, the values vary from 130 ~ to 320 ~ Polymers are sensitive to a greater or lesser degree to photo-degradation, which can limit their exterior uses. On the other hand, many polymers, including the commodities, are resistant to the chemicals usually met in industry or at home and displace the metals previously used for these applications" galvanized iron for domestic implements, gas and water pipes, factory chimneys, containers for acids and other chemicals... Polymers, like other materials, are sensitive to fatigue. Figure 1.7 plots some examples of fatigue test results according to the logarithm of the number of cycles leading to failure. To compensate for their handicaps in terms of properties compared to the traditional materials, polymers have effective weapons: 9 Manufacturing in small quantities or large series of parts of all shapes and all sizes, integrating multiple functions, which is unfeasible with metals or wood. 9 Possibility of selective reinforcement in the direction of the stresses. 9 Weight savings, lightening of the structures, miniaturization. 9 Reduction of the costs of finishing, construction, assembling and handling.

1000-

9~

100 -

10-

Magnesium ~ P O M / G ~ ~ C/GF Zinc

M ~ m

pSU

Log (number of cydes)

5

i

i

I

I

6

7

8

9

Figure 1.7. Examples of fatigue failure

11


9

9 9

Aesthetics, the possibilities of bulk colouring or in-mould decoration to take the aspect of wood, metal or stone, which removes or reduces the finishing operations. Durability, absence of rust and corrosion (but beware of ageing), reduction of the maintenance operations. Transparency, insulation and other properties inaccessible for the metals.

1.1.5 Material costs

Obtaining information on the prices is difficult and the costs are continuously fluctuating. The figures in the following tables and graphs are only orders of magnitude used simply to give some idea of the costs. They cannot be retained for final choices of solutions or estimated calculations of cost price. Usually, the material costs are considered versus weight but it is also interesting to examine: 9 The cost per volume, which is the most important for a fixed part size. 9 The cost linked to the rigidity for the engineering materials. 1.1.5. 1. Cost per weight of various materials

Table 1.10 and the graph in Figure 1.8 demonstrate that plastics and polymer composites are much more expensive than metals, even more specialized ones such as nickel.t Table 1.10

Order of magnitude of some material costs (~/kg) Minimum

Maximum

Thermosets DCPD

5

7

Epoxy

3

10

Melamine

2

4

Phenolic

2

7

Polyimide

70

160

Polycyanate

20

50

Polyurethane

3

7

1.7

2

2

5

4

7

0.8

160

0.2

0.4

Urea formaldehyde Unsaturated polyester Vinylester

Thermoplastics From commodities to high-tech

Metals Steel 12


Table 1.10

Order of magnitude of some material costs (~/kg)

Minimum

Maximum

Metals Special steel

1.4

2

Aluminium

1

2

Titanium

3

4

Copper

1.5

1.7

Nickel

5

6

0.6

0.8

Wood

Polymer composites Composite CF

140

Composite ArF

100

Composite GF

50

SMC

2-5

Composites Thermosets Thermoplastics Metals Wood

m i

1

Figure 1.8.

!

i

100

10

r

1000

Examples of material costs ~ / k g

1.1.5.2. Cost per volume of various materials

As for the specific mechanical properties, the high densities of metals modify the classification (Table 1.11 and Figure 1.9) of the various materials. Table 1.11

Order of magnitude of some material costs (~/litre)

Minimum

Maximum

Thermosets DCPD

5

7

Epoxy

4

10

Melamine

3

5

Phenolic

3

10

Polyimide

80

260

Polycyanate

24

60

Polyurethane

4

9

Urea formaldehyde

2

3 13


Table 1.11

Order of magnitude of some material costs (~/litre)

Minimum

Maximum

Tbermosets Unsaturated polyester

3

7

5

9

0.8

260

Steel

1.6

3.2

Vinylester

Thermoplastics From commodities to high-tech

Metals

Special steel

10

16

Aluminium

3

6

Titanium

13

18

Copper

13

15

Nickel

45

54

0.5

0.6

Wood

Polymer composites Composite CF

220

Composite ArF

140

Composite GF

100

SMC GF

4-10

Composites Thermosets Thermoplastics Metals Wood

II !

1

Figure 1.9.

10

......... | ' 100

~/litre 1003

Examples of material costs ~?/litre

According to the cost per volume: , Plastics are competitive. Only the very high performance plastics or composites are more expensive than metals. 9 Wood is the cheapest material. 1.1.5.3. [Performance~cost per litre] ratios of various materials

Table 1.12 and Figures 1.10 and 1.11 confirm that the composites are more expensive than metals for the same mechanical performances. It is necessary oexploit their other properties to justify their use. 14


Table 1.12

[Tensile properties/cost per litre] ratios of various materials Tensile strength (MPa per ~/litre)

Tensile modulus (GPaper ~/litre)

Metals & alloys Minimum

Maximum

Steel

187

562

65-130

Titanium

55

77

7

Aluminium

25

117

17

27

20

Wood 10

Polymer composites Unidirectional CF

8

14

1

Unidirectional A r F

10

11

1

Unidirectional GF

8

8

1

SMC G F

12

28

2-5

ArF: aramid fibre; CF: c a r b o n fibre; GF: glass fibre

Composites

Metals

Wood

1

Figure 1.10.

Figure 1.11.

!

!

10

100

MPaJ~/litre 1000

Examples of ratios "Tensile strength versus costs per litre"

!

!

10

100

GPa/~/litre 1000

Examples of ratios "Tensile modulus versus costs per litre" 15


1.2 What are thermosets, composites and hybrids? 1.2.1 Thermosets

Thermosets before hardening, like thermoplastics, are independent macromolecules. But in their final state, after hardening, they have a threedimensional structure obtained by chemical crosslinking produced after (spray-up moulding or filament winding) or during the processing (compression or injection moulding, for example). Figures 1.12 and 1.13 schematize the molecular arrangements of these polymers.

Figure 1.12. Thermoset before crosslinking or thermoplastic

Figure 1.13. Thermoset after crosslinking

Some polymers are used industrially in their two forms, thermoplastic and thermoset, for example, the polyethylenes or the VAE. Thermoset consumption is roughly 15-20% of the total plastic consumption. The links created between the chains of the thermosets limit their mobility and possibilities of relative displacement and bring certain advantages and disadvantages. 16


Advantages: 9

Infusibility: thermosets are degraded by heat without passing through the liquid state. This improves some aspects of fire behaviour: except for particular cases, they do not drip during a fire and a certain residual physical cohesion involves a barrier effect. 9 When the temperature increases the modulus retention is better, due to the three-dimensional structure. 9 Better general creep behaviour, the links between the chains restricting the relative displacements of the macromolecules, one against the other. 9 Simplicity of the tools and processing for some materials worked or processed manually in the liquid state.

Disadvantages: 9

The chemical reaction of crosslinking takes a considerable time that lengthens the production cycles and, often, requires heating, that is, an additional expenditure. 9 The processing is often more difficult to monitor, because it is necessary to take care to obtain a precise balance between the advances of the crosslinking reaction and the shaping. 9 Certain polymers release gases, in particular water vapour, during hardening. 9 The wastes are not reusable as virgin matter because of the irreversibility of the hardening reaction. At best, they can be used like fillers after grinding. 9 The infusibility prevents assembly by welding. The "pyramid of excellence" (see Figure 1.14) arbitrarily classifies the main families of thermosets according to their performances, consumption level and degree of specificity:

Figure 1.14. Pyramid of excellence for some thermoset families 17


9 Urea-formaldehydes (UF): old materials of modest properties. 9 Phenolic resins (PF) and melamines (MF): good thermal behaviour but declining. 9 Unsaturated polyesters (UP) and polyurethanes (PUR): the most used for their general qualities. 9 Epoxy (EP): broad range of properties. Some are used for high-tech composites. 9 Silicones (Si): flexibility and high heat resistance, physiological harmlessness. 9 Polyimides (PI): high-tech uses, limited distribution. 9 Polycyanates (Cy): highly targeted uses and very restricted distribution. 1.2.2 Polymer composites Polymer composites are made from" 9 A polymer matrix, thermoset or thermoplastic, 9 A non-miscible reinforcement closely linked with the matrix: fibres of significant length compared to the diameter, yarn, mats, fabrics, foams, honeycombs, etc. The consumption of composites with organic matrices is a few percent of the total plastic consumption. The main advantages of the composites are: 9 Mechanical properties higher than those of the matrix, 9 The possibility of laying out the reinforcements to obtain the best properties in the direction of the highest stresses. The development of the composites is held back by the recycling difficulties, attenuated in the case of the thermoplastic matrices. The "pyramid of excellence" (see Figure 1.15) classifies, as arbitrarily as for the thermosets, the composites according to their performances, consumption level and degree of specificity: 9 Unsaturated polyesters (UP) reinforced with glass fibres: the most used for their performances and low cost. 9 Phenolic resins (PF) reinforced with glass fibres: fire resistance, good performances and low cost. 9 Epoxy (EP) reinforced with glass fibres perform better than the UP/ GF. 9 Epoxy (EP) reinforced with aramid or carbon fibres or with honeycombs: high-tech and high cost composites performing better than the EP/GF. 9 Silicone (Si) reinforced with glass fibres: flexibility, heat resistance, chemical resistance and physiological harmlessness. I8


Figure 1.15. Pyramid of excellence for some composite families

9

9

Polyimide (PI) reinforced with aramid or carbon fibres or with honeycombs: very high-tech and high cost composites performing better than the EP composites. The consumption is limited. Polycyanate matrices: very specific uses, high-tech and high cost composites, very restricted distribution.

1.2.3 Hybrid materials

Hybrid materials are not really a clearly defined material category but result from a design method that associates, by integrating them closely, one or more polymers on the one hand and, generally, one or more other materials which provide one or more functionalities difficult or impossible to obtain with only one polymer. The limit between hybrid materials and associated ones is rather fuzzy. This definition does not regard as hybrids, for example, those polymers joined after their manufacture onto structures of metal or concrete. On the other hand, overmoulding on structural and functional inserts is regarded as hybrid. The hybrid techniques often associate polymers and metals and combine the benefits of the two material classes. The metal provides the rigidity and the overmoulded reinforced plastic keeps the shape of the metal and adds numerous functionalities. There is also a growing interest in the association of elastic polymers, which assume the sealing or damping functionalities, to rigid plastics or composites that have the structural role. One of the materials can be overmoulded on the other or the two materials can be co-moulded. 19


The polymer/metal hybrids allow, by associating simple and inexpensive plastic processes (injection moulding, for example) with simple and inexpensive metal processes (stamping, embossing, bending), the integration, thanks to the plastic elements, of the maximum number of functionalities: mountings, fastening points, fixings, cable holders, housings, embossings, eyelets, clips, etc. This leads to: 9 The elimination of the assembling stages of the suppressed components. 9 Reduction of the dimensional defects of the assembled components. 9 Avoids the welding operations able to cause metal deformations. This principle, in more or less complex versions, is applied to: 9 Front-end of recent cars such as the Ford Focus and VW Polo. 9 Footbrake pedals in metal/plastic hybrid. 9 Wheels of planes in hybrid metal/composite epoxy/carbon. 9 Car doors. 9 Frame-hull ( M O S A I C project) in hybrid composite/aluminium. Inversely, the polymer can sometimes provide the structural functions whereas the metal ensures a role not easily assumed by the polymer: 9 For high-pressure air tanks, it is a hybrid design that gives the best results: a thin metal liner ensures the sealing and is used as a mandrel to make the envelope by the filament winding technique. The aramid or carbon fibres ensure the mechanical resistance. The weight saving is 30-50% compared to the all-metal tanks while the costs are optimized. 9 The engines of the Polimotor and Ford projects are in hybrid composites of phenolic resins/glass fibres and epoxy/glass fibres with combustion chambers, cylinders and pistons in metal. This permits the direct contact with hot combustion gases that the polymer could not support. The composite provides the rigidity of the engine. 9 Certain incinerator chimneys are in hybrid stainless steel with inner lining in sandwich resin/glass fibres with core in foamed polyurethane. The materials associated with the polymers can also be concrete or wood: 9 Structural panels for individual construction, Azurel de Dow, made of wood and expanded polystyrene. 9 Rigid elements for the modular design of dwellings made of hollow structures of glass fibre reinforced unsaturated polyester filled with concrete. 1.3 Plastics: an answer to the designer's main problems

Designers are directly or indirectly subjected to economical, technical and environmental constraints. The thermosets and composites are well positioned to provide solutions. 20


1.3.1

Economic requirements

Cost savings on the total life of the parts. A polymer overcost can be compensated for by designing, processing, finishing, assemblage, operating and maintenance costs and by a longer durability. The plastics and polymer composites offer: 9 Design freedom: realization of all shape and size parts unfeasible with metals or wood. 9 Integration of several functionalities by using the property versatilities such as structural and other additional properties: damping, shock and noise absorption, heat insulation, electrical insulation, translucence or transparency, rigidity of UD composites or flexibility of some polyurethanes, thermal stability of silicones, polyimides... 9 The possibility to combine two polymer materials to ensure several functionalities if all the desired characteristics are not brought together in a single polymer. A polyurethane flexible foam and a rigid polyurethane can combine structural and damping properties in the same part. 9 The possibility of selective reinforcement in the direction of the stresses by selecting particular composites or by part drawing. 9 The reduction of design and production set-up times. 9 Weight reduction thanks to the good mechanical properties combined with low density. The resulting fuel saving in automotive, labour and handling savings in building and civil engineering...allow the reduction of the operating costs. 9 The aesthetics, the possibilities of bulk colouring or in-mould decoration to take the aspect of wood, metal or stone that remove or reduce the finishing operations. 9 The integration of functionalities, the large sizes permitted by certain processing methods, the particular processes of assembly lead to cost reductions of assemblage, to smoother surfaces without rivets or weldings favourable to aesthetic quality and to a greater aerodynamic optimization. 9 The opportunities of repairing the composites permit the recovery of expensive parts after damage. 1.3.2 Technical requirements

Solidity, reliability and permanence of the parts, increasingly harsher environments, higher temperatures... The plastics and polymer composites offer: 9 Durability, the absence of rust and corrosion (but beware of ageing). 9 Ease and reduction of maintenance. 21


Good fatigue behaviour, the slowness of the damage propagation, the possibility of targeting a damaged mode to preserve the essential functionalities of the part between two inspections. 1.3.3 Marketing requirements

Aesthetics, comfort, frequent renewal of the product ranges. The plastics and polymer composites offer: 9 Design freedom: realization of all shape and size parts unfeasible with metals or wood. 9 Adaptation to "niche" products. 9 Production flexibility: processing adaptability from the prototype to mass production. 9 The possibility to refresh or to renew the product lines more frequently thanks to the easier replacement and modification of tools with plastic than with metals. 1.3.4 Environmental requirements

The standards and regulations limit pollution and increase the level of recycled wastes. The plastics and polymer composites offer: 9 Weight reduction thanks to good mechanical properties combined with low density. This leads to fuel savings in automotive and transportation sectors, labour and handling savings in building and civil engineering..- that reduce the pollution. 9 The reduction or suppression of the periodic painting of metals contributes to a reduction in pollution. The recycling of wastes is difficult for the thermosets and composites because of the crosslinking and/or the presence of fibres broken during the recycling. 1.3.5 Some weaknessesof the polymer materials

Like all materials, polymers also have their weaknesses, general or specific. To start with, the reader may have noticed that all the quoted advantages are never joined together in the same polymer class. Moreover, polymers meet certain general obstacles as technical materials. Let us quote for example: sensitivity to impact, ageing, low rigidity, thermal behaviour, rate of production, recycling.

1.4 Outline of the technical and economic possibilities of processing A satisfactory combination of part, polymer and process is of the first importance: 9 Each process does not allow the fabrication of all types of parts 9 Not all polymers are suitable for processing by all the methods. 22


It is pointless to select a polymer of high performance if it is not, technically and economically, suitable to manufacture the part under consideration. For the choice of the process according to the part, the following points are the main ones to be considered: 9 The shape: parts of all shapes and limited sizes are, generally, manufactured by moulding by compression, injection, transfer and the derived methods such as RIM, RRIM, RTM... Parts of constant section are, generally, manufactured by pultrusion and derived methods. 9 The size" parts of enormous size are manufactured by hand lay-up, spray lay-up, centrifugal moulding, filament winding... 9 The aspect: a good aspect on the totality of the part surface is only obtained by moulding. The other processes leave either rough-cut sections or a more or less rough face. 9 The quantity to produce: the rate of output depends on the process. Injection moulding, RTM and SMC allow mass production whereas hand lay-up or spray lay-up moulding hardly exceed 1000 parts. 1.4.1 Thermosetprocessing

The processes used for thermoplastics are modified for the thermosets: 9 It is necessary to heat after obtaining the part shape for a sufficient time to crosslink the thermoset, which solidifies and gains its cohesion and final properties. 9 Due to the irreversible formation of a three-dimensional network during hardening, the thermosets cannot be processed by thermoforming or welding, and boiler-making is very limited. 1.4.1.1. Moulding the solid thermosets

They can be moulded by compression, compression-transfer and injection. Generally: 9 The part sizes are limited by the mould size and the press power. 9 The parts are isotropic. 9 The whole surface of the part has a good finish. Each process presents some particularities: 9 Compression moulding: o Is suited for small and medium output. o Thick parts are problematic because of the low thermal conductivity of the polymers. o Released gas cannot escape and induces voids and internal stresses. o Inserts are difficult to use. o Finishing is often essential. 23


o 9 o o o o o 9 o o o o o o

The o u t p u t rates are low, the m o u l d and press are relatively inexpensive, and the labour costs are high. Compression-transfer moulding: Is suited for m e d i u m output. The quality of the thick parts is particularly improved. Inserts are easy to use. Finishing is often simple. The o u t p u t rates, the mould and press prices, the labour costs are halfway b e t w e e n compression and injection moulding. Injection moulding: Permits total a u t o m a t i o n of the process. Is suited for mass production. The optimization of the moulding p a r a m e t e r s can be difficult and the part warpage is sometimes difficult to predict. Normally, finishing is unnecessary. A p a r t from the particular cases of resins filled with fibres and other acicular or lamellar fillers, the parts are isotropic. The output rates, the mould and press prices are the highest, and the labour costs are reduced to the minimum.

1.4.1.2. Moulding the liquid thermosets

They can be m o u l d e d by: 9 Simple liquid resin casting in an open or closed mould: o Is suited for small and m e d i u m output. o The part sizes are limited by the mould size. o Reinforcements can be arranged in the m o u l d before casting. o The parts are isotropic with neat resin or with isotropic reinforcements. o The aspect is correct for one part surface for open moulding, and for the whole part surface for closed moulding. A finishing step is often essential. o The moulds are inexpensive and there is no press but the labour costs are high. The output rates are low. 9 Low-pressure injection moulding, RIM, R R I M : o Are suited for m e d i u m output. o The part sizes are limited by the m o u l d size. o Reinforcements can be arranged in the m o u l d before injection. o The parts are isotropic with neat resin or with isotropic reinforcements. o The aspect is well finished for the whole part surface. o The moulds are pressure resistant and m o r e expensive than for the casting. A press and a mixing/injection unit are necessary but the labour costs are moderate. The output rates are in a m e d i u m range. 24


1.4.1.3. Secondaryprocessing

9 o o o 9

o

o

Boilermaking is reduced because of the 3D network that forbids thermoforming and welding. It is possible to use techniques such as machining, bonding of sheets, slabs, pipes, blanks... This technique allows the building of very large size tanks, cisterns, tubing, etc. from prototypes up to medium output. The workers must be skilled and the labour costs are high. Machining: practically all the thermosets can be machined to some degree by almost all the metal machining methods after adaptation of the tools and processes to a greater or lesser extent: Sawing, drilling, turning, milling, tapping, threading, boring, grinding, sanding, polishing, engraving, planing... The low thermal conductivity and the decrease of the mechanical characteristics at elevated temperature limit the machining temperature and it is necessary to cool and reduce the tool feed motion. Machining is suited for prototypes and low output of complex parts made from blanks whose mould could be simplified; it is also suited to making thick or tight tolerance parts.

1.4.2 Composite processing 1.4.2.1. Primary processes

The processes differ according to the nature of the matrix: 9 Thermosets: it is necessary to heat after obtaining the part shape for a sufficient time to crosslink the thermoset, which solidifies and gains its cohesion and final properties. 9 Thermoplastics: a cooling only may be necessary after obtaining the part shape. The processes are numerous and differ in their technical and economic possibilities. Let us quote for example: 9 Atmospheric moulding processes: hand lay-up, spray lay-up 9 Liquid moulding: RRIM, RTM, impregnation, infusion... 9 Solid state moulding: compression and injection, SMC, BMC, ZMC... 9 Prepreg systems 9 Bag moulding 9 Filament winding 9 Centrifugal moulding 9 Continuous sheet manufacture 9 Pultrusion 9 Sandwich composites... The process, the structure of the composites, the design of the parts, and the output are interdependent factors that cannot be isolated one from the others. 25


The shape of the parts must be adapted to the material and the process, which dictates certain conditions, for example, the maximum thickness, the thickness variations on the same part, the acceptable radius for the direction changes of the walls (depth of grooves, flanges, ribs...), the possibility of using reinforcement ribs and inserts, the possibility of creating apertures and cavities during the transformation, the aesthetics. The part sizes are limited by the tool sizes such as moulds, dies, autoclaves or winding machines and by the power and the size of equipment such as presses, bags, pultrusion machines... The following tables schematize some general technical and economic possibilities of various processes without claiming to be exhaustive. Other values may be recorded for the parameters concerned and not all the processes are examined. Table 1.13 shows some examples of the process choice versus the part characteristics. Table 1.13

Examples of the process choice versus the part characteristics

Part size, maximum area in m 2

Thickness, mm

Examples of parts

Smooth surface

Method

Virtually unlimited, 10 000

High

Low

Autoclave

250

Oxygen index, %

50-90

98-99

UL94 fire rating

V0

V0

Ageing: 2500 h in hot air 150 ~

modulus retention, %

90

175 ~


70-80

200 ~


40-75

200 ~

strength retention, %

10-35

Table 4.29

Phenolic foam: examples of properties

Density, kg/m 3 Stress to 10% compression, MPa Creep 48 h, 80 ~ Creep 7 days, 70 ~

30

40

60

0.060

0.100

0.250

20 kPa in compression, %

108 to >10 l~ . Dielectric constant, 1 kHz after 4 days at 20 ~ 85 % RH: 6- 20 9 Loss factor, 1 kHz after 4 days at 20 ~ 85% RH: 210

190-210

HDT A (1.8 MPa), ~

150-200

170-310

120-210

140-180

Continuous use temperature, ~

110-150

130-160

80-130

80-130

0.3-0.5

0.4-0.5


0.7

Specific heat, cal/g/~ Coefficient thermal expansion, 10-5/~ Resistivity Dielectric constant Dissipation factor, 10.4 Dielectric strength, kV/mm Arc resistance, s

0.4 1-4 1011-1013

3-5

1010--1012 1010-1013

6-11

4-5 1010-1012

7-10

7-9

400-1700

100-500

100-3000

1,000-3000

14-16

14-29

12-20

15-20

120-200

140-180

110-140

115-125

40-95

42-45

38-41

V0

HB to V0

V0

Oxygen index, % UL94 fire rating

1-3

V0

General chemicalproperties Light

Possible slight attack

Weak acids

Fair to limited resistance

Strong acids

Attack

Weak bases

Fair resistance

Strong bases

Attack

Organic solvents

Generally good behaviour with aliphatic, aromatic, chlorinated solvents, acetone, ethanol, esters, ethers

Food contact

Possible for specific grades

248


Table 4.33

Phenolic modified melamines: Characteristic examples

Filler

Woodflour

Cellulose Organic& inorganic Organic

Density, g/cm 3

1.5-1.7

1.5-1.7

1.5-1.7

1.5-1.7

Shrinkage, %

0.4-1.2

0.5-1.3

0.5-1.4

0.5-1.4

Ball indentation hardness, MPa

250-300

250-300

250-300

40-80

45-85

40-60

40-55

0.9-1.1

0.4-0.8 6-8

Tensile strength, MPa Elongation at break, % Tensile modulus, GPa

10-11

10-11

7-8

Flexural strength, MPa

80-135

90-130

90-110

Flexural modulus, GPa

7-9

7-9

6-8

200-250

200-250

150-200

1.5-2

1.5-2

1.5-2.7

HDT B (0.46 MPa), ~

190-220

190-210

220-240

HDT A (1.8 MPa), ~

160-180

160-180

180-220

140-150


80-130

80-130

110-140

80-150


0.4-0.6

0.4-0.6

0.6-0.7

0.3-0.4

Compression strength, MPa Notched impact, kW/m2

Specific heat, cal/g/~

1.5-2

0.3-0.4

Coefficient thermal expansion, 10-5/~ Resistivity

6-8

3-5

3-4

101~

Dielectric constant

1010-1012

1-4

1-4

1010-1012

7-9

7-9

5-8

5-8

1000-3000

1000-4000

200-1500

200-600

15-25

15-20

8-30

8-13

Arc resistance, s

115-130

125-135

Oxygen index, %

38-41

42-45

35-40

UL94 fire rating

V0

V0

V0

Dissipation factor, 10-4 Dielectric strength, kV/mm

130-180

General chemicalproperties Light

Possible slight attack

Weak acids

Fair to limited resistance

Strong acids

Attack

Weak bases

Fair resistance

Strong bases

Attack

Organic solvents

Good behaviour with aliphatic, aromatic, chlorinated solvents, acetone, ethanol, esters, ethers

249


Table 4.34

Filled unsaturated polyester modified melamines: characteristic examples

Density, g/cm 3

1.7-1.9

Shrinkage, %

0.1-1


150-350

Tensile strength, MPa

45-55

Elongation at break, %

0.6-0.8


9-10


60-110


9-11

Notched impact, kJ/m 2

2-3

HDT B (0.46 MPa), ~

220-250

HDT A (1.8 MPa), ~

120-220


110-140

Resistivity

1010-1014

Dielectric constant

6-7

Dissipation factor, 10-4

500-1500

Dielectric strength, kV/mm

20-25

Arc resistance, s

120-130

UL94 fire rating

HB to V0

Table 4.35

V0 cellulose filled urea-formaldehyde moulding powder: characteristic examples

Density, g/cm 3

1.5

Shrinkage, %

0.9-1.1

Water absorption, %

0.4-0.8


260-350


30-40


0.5-1


6-10


80-100


6-10

Compression strength, MPa

>200


1.3-2

HDT A (1.8 MPa), ~ Continuous use temperature, ~

250

110-145 70-80


Table 4.35

V0 cellulose filled urea-formaldehyde moulding powder: characteristic examples


0.3-0.4

Specific heat, cal/g/~

0.4

Coefficient thermal expansion, 10-5/~

3-5

Resistivity

10 l~

Dielectric constant

6-10


200-300

>300

320

330

180-250

180-250

200-250

200-250

Glass transition, ~ Thermal conductivity, W/m.K Coefficient thermal expansion, 10-5/~

250-350

300 0.2-0.5

0.3-0.5

0.3

0.5

1.5-5

1-5

1.5-3

1.4

Minimum service temperature, ~

-250 - -60

Volume resistivity, ohm.cm

1014-1016

Dielectric constant

-100 - -60 1015-1016

1014-1015

3-5

3--4

4-5


10--400

150

90


10-22

Graphite + aramid fibres

MoS2 + PTFE

Graphite + MoS 2

Friction

Friction

Friction

Arc resistance, s

Limited

Oxygen index, %

36--44

Filler

Graphite

Specific applications Density, g/cm 3

1.4-1.6

1.65

1.4

1.4-1.5

Shrinkage, %

0.3-0.6

0.1-0.2

1

0.2-0.6

Water absorption, 24 h, %

0.1-0.6

0.6

0.3-1.3

0.3-1.2

Rockwell hardness, M

100-110

94

113-115

95-110

291


Table 4.46 Thermoset polyimides for moulding: property examples Filler

Graphite

Graphite + aramid fibres

MoS 2 + PTFE

Graphite + MoS 2

30-65

30

10-35

30-40


1-6

0.3-0.4

0.5-1

300

>300

360

CUT unstressed, ~

180-260

200-260

180-250

180-250

Glass transition, ~

300

300

300

300

1.4-5

0.4-0.5

0.2-0.3

0.7-0.9

1-4

2.4-3.3

5-7

2.5


Thermal conductivity, W/m.K Coefficient thermal expansion, 10-5/~ Minimum service temperature, ~ Volume resistivity, ohm.cm

- 2 5 0 - -60

102-103

103-104

1012-1014

Dielectric constant

14

3-4


50

110-160


10

18-19

Oxygen index, %

36-50

30

General chemical properties are subject to the compatibility of the fillers and reinforcements with the ambient conditions. I f the fillers are adapted, the chemical properties are the same as the polyimide matrix. Light

Limited behaviour, preliminary tests necessary

Weak acids

Limited behaviour with hot acids

Strong acids

Limited to temperature

Bases

Attacked to a greater or lesser degree according to the nature, concentration and temperature

Solvents

Good general behaviour. Resistance to ethers, aromatics, esters. Attacked by certain alcohols, hot metacresol and nitrobenzene

Water

Generally, water absorption plasticizes polyimides. Possibly attacked by boiling water

Industrial fluids

Good resistance to the hydraulic fluids, kerosene, oils for gear boxes, Freon, silicone oils

CUT: continuous use t e m p e r a t u r e in an unstressed state 292

poor

behaviour

even

at

ambient


Table 4.47 Condensation polyimides for moulding: property examples Density, g/cm 3

Neat

Neat TP

30% glassfibre

30% carbon fibre

1.33-1.43

1.33

1.56

1.43

Shrinkage, %

0.8-0.9

0.4-0.5

0.2


0.2-0.4

0.2-0.3

0.2-0.33


92-102

104

105

168

233

Rockwell hardness, E Tensile strength, MPa

47 70-140

92 90


8-9


2-3


96-200

135

246

326


3-3.5

2.9

9-10

19-20

Compression modulus, GPa

2-4

3.2


110-280

190-195

210

120

108

Poisson's ratio Notched impact D 256, J/m Notched impact, kJ/m 2

3

2

12

21

0.4 80-90 17

H D T A (1.8 MPa), ~

235-300

242

247

CUT unstressed, ~

180-250

180-250

180-250

Glass transition, ~

315


0.1-0.4

Coefficient thermal expansion, 10-5/~

4.5-5.6

Volume resistivity, ohm.cm Dielectric constant

5

3-4 18-36


20-22

Oxygen index, %

44-53

15% graphite + 10% PTFE

15% MoS 2

Friction

Friction

1.4-1.6

1.6

3.3

15% graphite

40% graphite

1.4-1.5

1.6-1.7

Specific applications

Water absorption, 24h, %

0.49 0.6-4.7

1014-10 ~6


Density, g/cm 3

0.37 1.7-5.3

0.2

0.14

0.2

0.23


82-94

68-78

69-79

75-100


62-66

48-54

44-52

55-56


4-6

2-3

3-6

4


90-110

70-130

70


3-4

4-5

3

Compression modulus, GPa

2-3

3-4

1-2


100-140

90-110

77-105 293


Table 4.47 Condensation polyimides for moulding: property examples 15% graphite

40% graphiie

15% graphite + 10% PTFE

15% MoS 2

43

38

Friction

Friction

CUT unstressed, ~

180-260

200-250

200-250

180-260


0.4--0.9

0.9-2.1

0.4-0.8

2.3-4

3.8

2.3-3

Specific applications Notched impact D 256, J/m H D T A (1.8 MPa), ~

Coefficient thermal expansion, 10-5/~ Volume resistivity, ohm.cm

360

1012-1013

Dielectric constant

13-14


53-106

Density, g/cm 3

Thermoplastic PI Neat

Thermoplastic PI Friction

1.33

1.51

Rockwell hardness, M Rockwell hardness, E

37 47


92

107


90

3


135

96


2.9

6


80

H D T A (1.8 MPa), ~

262

Coefficient thermal expansion, 10-5/~ Dielectric constant

5

2.5-6.2

3.3

6.6

PV limit, MPa.m/s

17 (lubricated)

Coefficient of friction

0.09

General chemical properties are subject to the compatibility of the fillers and reinforcements with the ambient conditions. I f the fillers are well adapted, the chemical properties are the same as the polyimide matrix Light

Limited behaviour, preliminary tests necessary

Weak acids

Limited behaviour with hot ones

Strong acids

Limited to poor behaviour even at ambient temperature

Bases

Attacked to a greater or lesser degree according to the nature, concentration and temperature

Solvents

Good general behaviour. Resistance to ethers, aromatics, esters. Attacked by certain alcohols, hot metacresol and nitrobenzene

Water

Generally, absorbed water plasticizes polyimides. Possibly attacked by boiling water

Industrial fluids

Good resistance to hydraulic fluids, kerosene, oils for gear boxes, Freon, silicone oils

CUT: continuous use t e m p e r a t u r e in an unstressed state 294


Table 4.48 Undefined polyimides for moulding: property examples Neat

Density, g/cm 3

1.3-1.4

Shrinkage, %

40% glassfibres Aramid fibres and beads + MoS 2 + PTFE

Friction

1.6

1.4

1.4-1.7

0.3-0.6

0.8-1

0.1-0.6


0.2-0.3

0.2


92-120


72-86

80

30

20-55


7-8

1

1

0.3-4


3-4

2-11


110

45


8

3

55

35

80

Notched impact D 256, J/m Ratio tensile modulus or strength 250 ~ H D T A (1.8 MPa), ~

~

%

50

14-40 50-85

360

>300

>300

>300

CUT unstressed, ~

180-260

225

10 000

High pressure injection

Electric & electronic parts

Up to 4

Limited

Medium output

Stamping

Automobile parts

Up to 5

1 to 6

Mass production

Hot compression moulding mats and preforms

Car body elements

Up to 5

2 to 10

Mass production

Hot compression moulding prepregs

Car body elements

1000 to 250 000

RRIM

Housings

200 to 10 000

Resin injection

Car body elements

Up to 10 Up to 15

i to 10

345


Table 6.1

Examples of the suggested process choice versus the part characteristics

Part size, max area in

Up to 15

m 2

Thickness, mm

Output, units

Method

Examples ofparts

3 to 10

500 to 20 000

Low temperature & pressure compression moulding

Car body elements

200

Thermal expansion coefficient,10-5/~

1.7-2

Resistivity, ohm.cm

1011-1014

Dielectric constant

4

Dielectric rigidity, kV/mm

10-15

UL 94 fire rating

HB

Oxygen index, %

22

Glassfibre reinforcedfoamed epoxy composites Form of glassfibres, weight % Reinforcement weight, %

Chopped 38

Continuous Chopped Continuous 38

Grade

40

40

FR

FR

Density, g/cm 3

1.06

1.05

1.4

1.45


130

136

220

230


6.8

6.6

9.4

9.5

ILSS, MPa

10-12

12

17

18

Glass transition temperature, ~

80-127

80-127

128-134

128-134

460

Composites

6.8.8 Hybrid composites

Each composite family has its advantages and drawbacks. Thus it is interesting to combine two composite families to benefit from their best properties and to mask their weaknesses. We choose the example of an association of: . An epoxy composite of high mechanical properties and 9

A phenolic composite having excellent fire-resistant behaviour and satisfying the severe public transport standards for smoke emission and toxicity. Table 6.52 compares the smoke behaviour (in identical units) for phenolic and epoxy resins compared against two other plastics. Table 6.52

Property examples of epoxy syntactic foams

Reinforcement

Glass balloons

Density, g/cm 3

0.7-1.0

Shrinkage, %

0.3-1.0

Water absorption, 24h, %

0.2-1


15-30


3-5

Izod notched impact, J/m

8-13


0.5-1.5

H D T A (1.8 MPa), ~

90-120

Thermal conductivity, W/mK Table 6.53

0.15-0.25

Examples of smoke emission for selected plastics

Method Without flame

~YcTthflame

2

16

132-206

482-515

Vinylester resin

39

630

PVC

144

364

Phenolic resin Epoxy resin

Thanks to co-curing techniques, it is possible to simultaneously crosslink an epoxy and a phenolic resin. The epoxy prepreg is applied directly onto the honeycomb and then covered with phenolic prepreg. Both are cured simultaneously. This system is used, for example, in the production of the honeycomb sandwich structures for civil aircraft floors. Table 6.54 displays some property examples of fire-proofed epoxy and hybrid composite. 461


Table 6.54

Selected properties example of fire-proofed epoxy and hybrid composite Fire-proofed e p o x y

Co-cured EP/PF

Flexural strength

MPa

540

562

ILSS

MPa

42

45

Glass transition temperature

~

115

115

N

400

410

Peel strength of the honeycomb skin

6.8.9 Conductive composites

Composites can be rendered conductive, anti-static or resistant to EMI by several method, such as: . Metal coatings: application of sheets or strips of metal, metallization. 9 Addition of conductive ingredients in a sufficient quantity to exceed the threshold of percolation: metal powders, graphite, metal fibrils, carbon blacks. 9 Use of conductive reinforcements: metallized glass fibres, carbon fibres, steel fibres. The resistivities range from less than 1 ohm.cm up to 106 ohm.cm. The mechanical properties can be affected. Table 6.55 compares some properties of conductive and neat plastics.

Table 6.55

Examples properties of conductive and neat plastics Polypropylene

Fibres

None

Stainless steel

Carbon

Resistivity, ohm.cm

1017

10 3

10 3

30-40

41

41

1.3

1.4

4.3

ABS

PA66

PPO

Tensile or flexural strength, MPa Flexural modulus, GPa EMI grades compared to neat polymers Aluminium powder, %

0

40

0

40

0

40

1.1

1.57

1.1

1.48

1.1

1.45


30--65

23-29

40-85

41

45-65

45


3-60

2-5

150

4

2-60

3

1-3

2.5

1-3.5

5

2.5

5.2

6-10

4

5-14

2.2

3-8

1.1

100

95

85

190

110

110

Density, g/cm 3

Tensile modulus, GPa Thermal expansion coefficient, 10-5/~ H D T A (1.8 MPa), ~ 462

Composites

References Technical guides, newsletters, websites 3M, 3Tex, Airex, Alusuisse, Alveo, Asahi Fibre glass, Astar, Azdel, Baltek, BASE Bayer, Besfight, BF Goodrich, BFG Int, Bond Laminates, BP, Borealis, Bryte, Ciba, CO1 Materials, Cray Valley, Cytec, Diab, Dow, DSM, DuPont, EMS, European Alliance for SMC, Ferro, Fibre Glast, GE, Haufler, Haysite, Hexcel, Isosport, Jet Moulding Compounds, Lankhorst Indutec, LNP, MatWeb, MFC, Mitsubishi, Neste, Owens Corning, Parabeam, Plascore, PPG, PRW, Quadrant, Rhodia, R6hm, RTP, Sabic, Saint-Gobain, Scott Bader, Silenka, Sintimid, Soficar, SP Systems, Stratime Capello Systemes, Sulzer Composites, Symalit, Thermotite, Ticona, Toray, Tubulam, Twaron, Vetrotex, YLA, Zherco Plastics, Zoltek, Zyex. Reviews Plastics Additives & Compounding (Elsevier Science) Engineering & Manufacturing Solutions for Industry Composites (Ray Publishing, Wheat Ridge, CO 80033, USA) High Performance Composites (Ray Publishing) Modern Plastics (ModPlas.com) Reinforced Plastics (Elsevier Science) Techniwatch (CRIF) Papers [1] A. Garcia-Rejon et al. (Antec 2002, p. 410) [2] A.K. Bledzki, J. Gassan, M. Lucka, International Polymer Science and Technology, Vol 27, No. 8, (2000), p. T/75 [3] A.R. Bunsell, Fibre Reinforcements for Composite Materials, Elsevier [4] J. Klunder, Introduction to glass fibre reinforced composites, Second edition, (1993); available from: PPG Industries Fiber Glass bv, Mail Box 50, 9600 AB Hoogezand, The Netherlands

463

Chapter 7

Future prospects for thermosets and composites


The consumption of thermosets and composites is controlled by: 9 User market demand. 9 The ability to adapt these materials to the economic and technical market requirements and to propose technological advancements. 9 The capacity for innovation in terms of materials and processes. 9 Adaptability to the environmental constraints: recycling, sustainable matrices and reinforcements. The purpose of this exploratory study is to give background information on these various points.

7.1 The Laws and requirements of the market Apart from exceptional cases, any manufacturer is subject to general regulations induced by the economics of competition, customers' rights and requirements and the legislative arsenal. Figure 7.1 points out some of the main market constraints. While the majority of these points speak for themselves, others need to be restated.

Figure 7.1. Laws and requirements of the market 466


Reduction of production costs

Cost 9 9 9 9 9 9 9 9 9

prices are optimized by reductions in: The number of parts necessary to satisfy all the functions. Raw material costs. Weight of the parts. Investments. Payroll. Scrap. Manufacturing costs. Finishing costs. Joining and assembly costs.

Adaptability Customers' requirements, changing fashions and technological developments involve a shortening of product life cycles. The manufacturers thus turn to materials allowing fast and economic design and easy adaptation of the production equipment. Guarantee

The extension of warranty periods is viable only if the performance and the durability of the product make it technically possible. Operating cost

This depends on: 9 The costs of in energy, process fluids and others. 9 Maintenance expenses: simplification of maintenance and cleaning; reduction of repair and restoration operations. 9 Durability. User satisfaction

This is a combination of a multitude of objective or subjective parameters, for example: 9 Ease of use and maintenance 9 Reliability 9 Aesthetics. 9 Lack of noise and vibration in operation.

7.2 Thermoset and composite answers and assets The use of thermosets and composites makes it possible to satisfy some of the requirements listed above, provided all the players are involved from the beginning of the project and problems such as the process of transformation and downstream recycling are taken into account from the start of the design phase. The diagrams in Figures 7.2 and 7.3 propose general schemes of the services to involve and the parameters to be taken into account. 467


Design Project m a n a g e r

Marketing

M e c h a n i c s design office

Pricing office Environment department

Plastic design office

Styling

O&M department

Plastic design Mould maker

Plastic design office

O&M department

Moulder

I I

R h e o l o g y study

T h e r m a l study

Cost price Pricing office

I I

I I

O&M department

Testing Testing lab O&M department

I I I I

Quality insurance

I I

Processing

Figure 7.2. Design diagram

At the design stage it is necessary to seek: 9 The best performance/density/cost compromise giving the best cost with the lowest weight and sufficient performance levels to meet the requirements. Plastic/metal or plastic/wood/metal hybrid materials are sometimes excellent solutions. 9 Integration of the functions to reduce the number of parts and minimizes the costs of materials, processing, finishing, assembly/ joining and intermediate storage. 468


Draft scheme Characteristics Processing

I I

Style Cost

f

Functionality integration

Design Drawing and computing Characteristics Durability I

I Feasibility I Rheology/thermic/shrinkage Part conformity |

I [

Material cost II

[

Testing

I I I I

Environmental impact

I Processing method Finishing & assembly Recycling

Tool design

I I I I

Cycle time Cavity number Cost forecast

Cost price [ [

Processing cost

Control

I

] ]

Quality insurance

Figure 7.3. Project diagram

9 The design of the parts that optimizes the thicknesses and reduces weights and cycle times. 9 Processing methods that are adapted to the product, and that allow the series to be manufactured with the simplest tools and minimal investment. The combination of several techniques, for example extrusion or moulding and machining, can bring economic solutions. 9 The possibility of bulk colouring and in-mould decoration, which can simplify or avoid the finishing operations. 469


9 The simplest assembly and joining methods. At the manufacturingstep it is necessary to ensure: 9 The adequacy of the machines and tools for the parts to be manufactured and the materials to be processed, in order to ensure optimal properties and reduce waste. 9 Good maintenance of the machines and tools to ensure the accuracy of the size and geometry, combined with optimal properties, a minimum of finishing operations and a minimum of waste. 9 The reasonable use of quality assurance and strict procedures to make the production reliable and to limit wastes. Provided the design and manufacturing requirements are met, plastic components can offer: 9 Lower costs which, in certain cases, make it possible to develop new applications. 9 A light weight involving fuel savings for vehicles, reduced expenses for packaging and transport, decreased waste at the end of the product life. 9 Corrosion resistance decreasing the maintenance or renovation costs for boardings, roofs, etc and in composites. 9 Transparency for certain families and grades, such as unsaturated polyester glazings. 9 Better impact resistance than glass. 9 Greater design freedom than many traditional materials such as metals (realization of forms unrealizable with metals). 9 Reduction and miniaturization of parts by the integration of functions and co-transformation (combination of flexible and rigid parts or compact and cellular parts). 9 A faster adaptation of manufactured parts thanks to easier replacements and modifications of tools than with metals. 9 A shortened timeframe for design, development and manufacturing. 9 Aesthetic properties and versatility of surface aspects. 9 Possibility of bulk colouring. 9 Possibility of decoration to obtain traditional material appearances such as wood or metals. 9 Good thermal insulating properties allowing energy savings (building) and comfort improvement. 9 Good electrical insulating properties. 9 Damping properties: lower noise, improvements to comfort and safety (polyurethane foams for seating and so on). 9 Ease of handling and installation. On the other hand, it is necessary to be aware of the ageing, mechanical resistance and thermo-mechanical behaviour, which are different from 470


those of metals. The recycling of thermosets and composites presents some difficulties that are not generally solved in a satisfactory way. To achieve greater market penetration, thermosets and composites must enhance prices, performances, characteristics, productivity, ease of processing and recycling. Among the ways to success we can cite: 9 Improvement of the cost/performances ratios. 9 Improvement of the immediate and long-term characteristics, after use and ageing, for the conquest of structural parts. 9 Better thermal resistance. 9 Better weathering behaviour. 9 Enhancement of the colouring and surface appearance. 9 Improvement of the surface properties: scratch resistance, dusting, staining, tarnishing, chalking and so on. 9 Adaptability of the grades, which must satisfy the requirements of the market and develop specific properties, for example coefficient of friction, electrical conductivity, better combination of mechanical properties/thermal behaviour/electrical characteristics/ageing. 9 Availability of halogen-free fire-retardant grades. 9 Improvement of the adherence of paints, printing inks, adhesives. 9 Better low-temperature performances: the legal requirements are moving towards an increase in the impact resistances at low temperature with a ductile behaviour. 9 Ease of processing: improvement of the flow properties and the aptitude for injection lead to cycle time shortening and better productivity. 9 Improvement of the mould productivity: cooling, use of multiple cavities. 9 Automation of the process equipment. 9 Better control of the processes by statistical processing of the recorded parameters (SPC). 9 Development of new manufacturing methods. 9 On-line compounding to reduce costs and thermal degradation. 9 Hybrid combinations with non-plastic materials, for example: o Assembly of plastic panels onto a metal structure allowing very large objects to be obtained for extremely low investments. o Hollow glass fibre reinforced polyester elements filled with concrete to form rigid structures for modular dwellings. 9 Use of wastes and recycled materials to satisfy environmental requirements and lower the costs. 9 Management of recycling, which starts with the design reducing the diversity of the materials used, improving their compatibility, the marking of the parts and their dismantling ease. The subsequent waste collection, recycling and outlets require work on economical and technical issues. 471


7.3 Markets: what drives what? The forces driving development 7.3.1 Consumption trends

In round figures, after an average increase of 3 % per year during the 1990/ 2000 period, the consumption of thermosets might increase by up to 4 % per year during the next few years. The growth of the consumption of composites in industrialized countries is also approximately estimated at a few percent per year (see Table 7.1). Environmental regulations and trends favour: 9 Thermoplastic composites. 9 Sustainable materials. 9 Water-based or powder-based adhesives, coatings and so on. The preference granted to thermoplastics compared to thermosets and their composites stems from some inherent handicaps of the latter such as" 9 The relative scarcity of materials, equipment and manufacturers. 9 The additional curing step, consuming time and money. 9 The longer processing cycles. 9 Greater difficulty in recycling. Table 7.1 Annual growth (%) in major thermoset and composite consumption TheYmosets

Polyurethanes

4

Amino resins

3

Unsaturated polyesters

4

Phenolic resins

4

Epoxies

5

Combined total for the major thermosets

4

Composites Automobile & transportation

5

Corrosion protection

5

Shipbuilding

5

Electricity & electronics

4

Sports & leisure

4

Railway

4

Medical

4

Aeronautics

3

Building & civil engineering

2

Mechanics & industry

2

Combined total for composites

4

472


7.3.2 Requirements of the main markets

The 9 9 9 9

main expressed requirements are: Automotive: costs and recycling. Aeronautics" costs and durability. Electricity & electronics: costs, recycling, conductive polymers. Building and public works: durability with a 50-year objective, processing and cost. 9 Shipbuilding: durability, industrialized processing, and costs. 9 Sports & leisure: cost and low weight. 9 Railway: fire behaviour, cost, processing. 9 Medical: performance, biocompatibility, cost, processing. 9 Mechanical & industrial: cost, processing. For each market there are also underlying demands and the global requirement list can be estimated as follows" 9 Cost and [cost/performance] ratio. 9 Recycling and outlets. 9 Processing: the objectives depend on the market and cover all situations from fully automated processes for automotive mass production to unitary processes for prostheses. 9 Performance, including manufacturing possibilities from very small to giant parts. 9 Durability including aesthetics. The lifetime requirements vary from a few years to 50 years according to the market. 9 Light weight and [weight/performance] ratio. 9 Fire behaviour: halogen-free fire-retardant behaviour; low smoke emissions of low toxicity. 9 Electrical conductivity: from antistatic to metal conductivity.

7.4 Cost savings 7.4.1 Material costs

There are several ways to cut down material costs: 9 Choose a cheaper family with the proviso that the performances are of a sufficient level to satisfy the functions. 9 Use a reinforced grade to reduce the wall thickness and consequently the material weight. In ascending order of performance but also of cost, the most used reinforcements are: natural fibres, glass fibres, aramid fibres, carbon fibres. Carbon fibres, if their development leads to a substantial lowering of their cost, could solve many cost problems. 9 Increase the performances and costs to lead to a very substantial improvement in performances, particularly in the durability of the finished part, which reduces the number to manufacture and to recycle, and the associated costs. 473


7.4.2

Hybrids

The hybrid materials as defined and described in Chapters 1 and 2 above are developing because of the substantial cost cutting due to: 9 High function integration thanks to the plastic elements that allow integration of fixings, housings, embossings, eyelets, clips etc. avoiding: o The assembly of the integrated components. o The stacking of the dimensional defects of the integrated components. o Later operations of welding capable of causing deformations. . The combination of simple processes from plastic and metal technologies. Each material has its advantages and drawbacks. The hybrids that closely associate two or more families benefit from their best properties and mask their weaknesses. The polymer can often bring: 9 Aesthetics and style. 9 Global cohesion of all the components. o Damping. 9 Thermal and electrical insulation. The metals often bring: 9 Structural properties. 9 Impermeability. 9 Electrical conductivity. There are exceptions, such as high-pressure tanks, where the polymer composite provides the structural function. Several producers such as Bayer, Dow (LFT-PP concept), Rhodia (PMA and MOM processes) have developed their own hybrid technologies. A typical development is the front-end of recently introduced cars such as the Mini Cooper from BMW or Mazda 6 in which long glass fibre reinforced polypropylene is injected onto stamped metal. The weight saving is in the range of 30-35 % compared to traditional solutions with a high function integration. 7.4.3 Processing costs

Intensive processing research is based on several routes to reduce costs: 9 Globalization of the processing, from raw material to finishing. o Automation. , Industrialization. 9 Simplification. Some examples are listed below. 474


7.4.3.1. Example of compounding integrated on the process line

The integration of the compounding of long glass fibre reinforced thermoplastics on the process line is an example of the globalization and automation of the process. This technique brings cost savings and decreases the thermal and mechanical degradation by avoiding one step involving plasticization and re-heating of the material. In the principle, the glass fibres are chopped and added to the thermoplastic in a special extruder/mixer synchronized with the shaping processing equipment to feed it with plasticized, hot material. The economy is expected to be of the order of ~0.30 per kg and mechanical properties are improved. 7. 4.3.2. New or modified processes

Traditional processes can be modified to better industrialize the manufacturing of medium or short run manufacturing. A good example is Resin Transfer Moulding (RTM), which leads to numerous variations such as: D R I V (Direct Resin Injection and Venting); LRTM (Light RTM); RIRM (Resin Injection Recirculation Moulding); SCRIMP (Seeman's Composite Resin Infusion Moulding Process); V A R I (Vacuum Assisted Resin Injection); V A R T M (Vacuum assisted RTM); and VIP (Vacuum Infusion Process). In the thermoplastic composite field, the "Pressure Diaphorm Process" allows the processing of continuous fibre reinforced thermoplastic with low pressures. The press and the moulds (wood, composite or aluminium) can be about 70% cheaper. The process is convenient for short and medium runs in the range of 1000 up to 100 000 parts. 7.4.3.3. Integrating finishing in the process

In-mould coating with special gelcoats and in-mould decoration with films reduce the finishing operations. If the process and its operating conditions are suitable, the demoulded parts are finished. As an example, composite manufacturer Quadrant Plastics Composites is studying three solutions for the decoration of GMT body panels: 9 Coil-coated aluminium 9 PMMA-based films (Senotop) already used for the Smart City Coup6 roof. 9 PP-based films. 7.4.4 Low-cost tool examples

There are numerous solutions. We cite a selection. 9 The LCTC (Low Cost Tooling for Composites) process developed by Boeing for short run manufacturing of parts by the autoclave process combines the use of aluminium plates and honeycombs bonded with a RTV adhesive. The machining is carried out in two steps, partly 475


before adhesive curing and finally after cure before surface sealing. A cost saving of 35-50% is claimed. This technique has been used to produce 50-part runs. 9 The Modular Tooling Concept developed by Intellitec for aerospace RTM applications. The principle is to use" o Common mould base for several parts of homogeneous sizes. o Interchangeable cavity sets for each part. In the case of a helicopter project, two modular moulds could produce thirteen parts with a cost saving of 60% versus traditional tooling. 9 The RenTooling System uses an aluminium honeycomb and an epoxy paste to produce lightweight and stable tools. 9 Water-soluble tooling materials such as Aquacore or Aquapoured can be moulded and machined to make strong cores that are then eliminated by water washing. The machining of the moulds is highly simplified.

7.5 Material upgrading and competition 7.5.1 Carbon nanotubes (CNT)

Carbon nanotubes are hollow carbon cylinders with hemispherical endcaps of less than 1 nm to a few nanometres in diameter and several microns in length. The aspect ratios are in the order of 1000 and more. The elementary nanotubes agglomerate in bundles or ropes that are difficult to disaggregate. The main properties are: 9 Very high modulus of the order of 1000 GPa and more. 9 Very high tensile strength of 50 000 MPa and more. 9 A low density: 1.33 g/cm 3. 9 High electrical conductivities with a very high current density of the order of 109 A/cm 2. 9 High thermal conductivities of the order of 6000 W / m K . 9 Very high cost: ~1 million per kg in 2000. ~100 000 and more per kg in 2002. ~100 per kg expected in 2005. The CNT developments in the polymer field concern: 9 Polymer reinforcement. 9 Compounding with polymer to obtain extrinsic conductive polymers with nanotube levels lower than 1% to produce ESD, EMI compounds and ultra-fiat screens. 9 High thermally conductive polymers for electronics. Industrialization of these developments is foreseen in few years. 476


7.5.2 Molecular reinforcement

The concept of polymer reinforcement by monomolecular fibres is already old but many studies date from the last decade. The interest is particularly the very high aspect ratios and the levels of reinforcement with expected mechanical properties as high as: 9 50 GPa up to more than 400 GPa for the modulus, 9 1000 MPa up to more than 40 000 MPa for tensile strength. This is a difficult technique and today the best laboratory samples reach: 9 100 GPa up to 300 GPa for the modulus, 9 1000 MPa up to 3000 MPa for tensile strength. Industrialization is not currently foreseen. 7.5.3 Polymer nanotubes

The Max-Planck Institute has developed a process to manufacture polymer "nanotubes" with submicronic sizes of the order of hundreds of nanometres. The mechanical properties would be expected to be attractive. Industrialization is not yet in sight. 7.5.4 Nanofillers

The main problem with nanofillers is the need for complete exfoliation. Some special compounding techniques have been developed such as, for example, the ZSK M E G A compounder by Coperion Werner and Pfleiderer with a special screw configuration. Following GM and Toyota, Fiat projects new applications for nanocomposites in the form of PA fuel lines incorporating PA nanocomposite barrier layers from Ube. Fiat expects to launch this development on a new car model in 2003 or 2004. Ube developed the PA nanocomposite named "Ecobesta" to replace PVDF or other traditional barrier materials. The all-polyamide structure offers recycling advantages compared to traditional multi-material designs. It incorporates: 9 A P A l 2 outer layer; 9 A PA6/12 adhesive layer; 9 A PA6/66 barrier layer incorporating 2% nanoclay; 9 A PA6 inner layer in contact with the fuel. Ube produces the PA nanocomposites by the in-situ polymerization route. 7.5.5 Short fibre reinforced thermoplastics to compete with LFRT

Borealis has developed a high performance short glass fibre reinforced polypropylene (HPGF) family that has the technological and economical potential to replace long glass fibre (LFRT) in highly stressed parts for technical automotive applications. 477


The advantages of the L F R T products are offset by requirements to optimize the whole process chain including extruder screw design, processing parameters and mould design, thus needing higher investment and production costs. By contrast, the processing of H P G F compounds requires no additional investments as it utilizes standard injection moulding machines. The high performances of H P F G are due to a better coupling of fibre and matrix, and the properties are near those of the L F R T grades with some advantages: 9 Lower emissions, lower fogging and lower odour than L F R T grades. 9 Improved weldability, increased flowline and weldline properties. 9 Better fatigue behaviour. Xmod TM G30 grade containing 30% glass fibres shows, compared to a conventional 30% GF reinforced polypropylene: 9 A significant improvement of tensile modulus over a range of temperatures tested up to 140~ 9 Better impact behaviour. 9 Significantly increased tensile strength to 115-120 MPa. Compared to LFRT, H P G F brings: 9 Retained weldline strength over twice the value for L F R T grades. 9 Superior fatigue behaviour, as measured by fatigue crack growth rate. 9 Tensile strength in the 115-120 MPa range versus 125 MPa for an LFRT. 9 Slightly lower impact strength. These improved properties of H P G F grades make them suitable for use in the automotive industry, with the potential to replace metal or long glass fibre polypropylene: 9 Front-end carriers moulded in H P G F grades could be an economically better solution than those using L F R T polymers. 9 Dashboard carriers: low emission and fogging values are achievable with HPGF. 9 Pedal carriers: H P G F performs better than LFRT in weldline behaviour. 9 Air intake manifold applications. 9 Fan supports and shrouds, drive belt covers, blower wheel covers, bases for air filters, battery supports, engine covers and parts for the cooling system are further potential applications. 7.5.6 Thermoplastic and thermoset competition

There are numerous examples ranging from mass production, such as automotive applications, to the high-tech industry such as aeronautics. We mention two examples: 478


9

9

The use of BMC or glass fibre reinforced polyamide for engine covers: the two techniques are industrialized. One is predominant in the USA, the other in Europe and Japan. The main characteristics are roughly similar, as shown in Table 7.2. The use of glass and carbon fibre reinforced thermoplastics for aircraft elements.

Table 7.2

Property examples of BMC and glass fibre reinforced polyamide BMC

PA

10-30

30-43


40-135

175-210


5-11

6-9

Glass weight, %

HDT A, ~ Melt temperature, ~ Izod notched impact, J/m Thermal expansion coefficient, 10-5/~

>260

248-251

Non-fusible

255-260

300-600

100-250

1.4-2

2-3

There are numerous studies and some industrialization of fibre reinforced engineering thermoplastic uses in aeronautics, for example" o Lockheed F-22: carbon fibre reinforced P E E K and PEI processed by SuperPlastic Diaphragm Forming (SPDF) technique. o Fairchild Dornier 328, a regional transport: carbon fibre reinforced PEI for flap ribs. o Airbus A340-500/600: glass fibre reinforced PPS for 3 m long components, carbon fibre reinforced PPS and honeycomb for inboard lower access panels. o Prototype fuselage panel by Cytec Fiberite: carbon fibre reinforced P E E K and PEI. o National Aerospace Laboratory investigations of the fibre reinforced LCPs. In all these cases, the cost and weight savings are significant. 7.5.7 3D reinforcements compete with 2D 2D reinforced composites have lower performance between the layers of fabrics and other 2D reinforcements. To enhance performances in all the directions, numerous 3D reinforcements have been developed. Several concepts are marketed, such as: 9 Woven 3D fabrics such as 3Weave Z Advantage by3Tex. 9 Stitched glass reinforcements such as Multimat or Multiaxials by Vetrotex. 9 Two glass decklayers bonded together by vertical glass piles such as Parabeam by Parabeam Industrie. 479


7.5.0 Carbon fibres compete with glass fibres

For many properties carbon fibres have better performances than glass fibres and are also lighter, although more expensive. However, the cost has been decreasing for several years and it is expected that, with their industrial development, this trend will continue. Currently the average price of a finished part incorporating carbon fibres is 50% higher than that of the finished part made with glass fibres, although the carbon fibre price is far higher than that of glass fibre. Zoltek anticipates that a price of ~12/kg could involve the use of carbon fibres in mass production. This is not unrealistic and the replacement of glass fibres in BMCs and SMCs for highly-loaded body components is foreseen. Today ~14/kg appears to be a sustainable prospect and leads to new developments. So: 9 Between 2000 and 3000 General Motors' "Commemorative Edition" Corvettes will be fitted with a carbon fibre reinforced epoxy resin bonnet for the 2004 model. This is the first time that carbon fibre has been used in original equipment for a painted exterior panel on a vehicle produced in North America: The bonnet: o Weighs almost 5 kg less than the glass fibre SMC o Has a similar thickness to stamped sheet metal o Has a Class A surface finish o Withstands the high temperatures of prime and paint ovens o Is fully cured in ten minutes at 150 ~ thanks to a quick-cure epoxy resin. Production combines automated and manual processing techniques. 9 In 2003, DSM launches a carbon fibre reinforced vinylester SMC for semi-structural and structural automotive parts that do not require a Class A surface finish. The SMC flows well and cycle times are similar to those of standard SMC. The specific weight and mechanical properties are significantly better. The compound was developed in cooperation with DaimlerChrysler. 9 Menzolit Fibron have presented (JEC 2003) an automotive body demonstrator made of an advanced SMC reinforced with carbon fibres leading to a weight saving of 60% versus steel with a highquality surface finish. 9 In the wind energy industry, all-carbon constructions are making their entry into the highly-stressed elements of large wind turbine blades, saving half of the weight of glass-reinforced elements and increasing the stiffness. The higher cost of carbon fibres is compensated by the low weight of carbon elements, which leads to a decrease in weight of all the other bearing components of the wind turbine. Glass/carbon hybrid lamination is also being investigated. 480


7.5.9 New

highperformancepolymers

Launching new polymers of medium-range performance is a difficult operation economically, as proved by the case of the aliphatic polyketones. New polymer families are rarely marketed but there are some examples where they provide improved thermal performances or, more exactly, a better balance of: 9 Thermal behaviour: with high-performance retention for short periods of high temperature for aeronautics applications such as skins of hypersonic aircraft, and/or long-term performances. 9 Ease of processing. 9 Lower final cost: composites can be less expensive than titanium after processing. Beside the bismaleimides (BMI), polyimides (PI) and cyanate esters are appearing, for example: 9 New polyimides such as PETI 5. 9 Benzocyclobutenes and their derivatives. 9 Polyetheramide resins (PEAR) from bisoxazolines and phenolic novolacs. 9 Phthalonitrile resins. 9 Phenolic triazine (PT). The benzocyclobutenes are already used in electronics but their applications in the structural field are in the course of investigation. Their functionalization would make it possible to reticulate them in a solid state to lead to an increased resistance and a better creep behaviour. They could also be used to modify existing thermoplastics such as polyamides, polyimides or LCP. The functionalization could also be used to initiate a reticulation at high temperature, which could improve the fire behaviour. NASA (NASA TechFinder), within the framework of its research into matrices for composites for the future High Speed Civil Aircraft (HSCT), tried out a panel of 200 oligomers of phenylethynyl with imide terminations (PETI). PETI-5, manufactured using components already available commercially, has excellent properties and a lifespan higher than 60 000 h (6.7 years) at 177 ~ PEAR, high performance polymer resins developed by Ashland, combine strength, chemical resistance, excellent thermal stability, low levels of toxic fumes and smoke when subjected to fire, electrical insulation properties and long fatigue life. Viscosity is low and P E A R accepts high fibre and filler loading. Adhesive characteristics are good compared with other materials. Consequently, P E A R is a candidate for the next generation of aircraft. Phthalonitrile resins were developed by the US Naval Research Laboratory (NRL). The cured resin exhibits good thermal and oxidative stability with useful long-term mechanical properties up to 371 ~ There is no indication of a glass transition up to 500 ~ The low melt viscosity of uncured resin allows it to be used in the RTM process. The low level of 481


toxic fumes and smoke when subjected to fire qualifies it for use inside submarines. The continuous use temperature is of the order of 300 ~ however, phthalonitrile can be used at much higher temperatures in applications such as missile structures, where the high temperatures exist for only a few minutes. To provide a comparison, high mechanical performance retention is claimed for carbon composites in short duration tests: 9 for epoxy resins at 150 ~ up to 200 ~ 9 for P E A R at 200 ~ up to 370 ~ 9 for BMI at 250 ~ up to 400 ~ 9 for phenolic triazine at 370 ~ up to 500 ~ 9 for phthalonitrile at 400 ~ up to 500 ~ 9 for new polyimides at 400 ~ up to 500 ~

7.6 The immediate future seen through recent patents Recent patents have been analysed by polymer type, reinforcement type, and material structure and process type. The selected patents do not relate to part manufacturing because of the difficulty of eliminating those relating to non-composite uses, for example, the use of melamines for adhesives or the use of glass fibres for insulation. 7.6.1 Analysis of patents by polymer type

The graph in Figure 7.4 positions the main thermosets compared to two frequently used thermoplastics, a commodity (polyethylene) and an engineering thermoplastic (polyamide).

Figure 7.4. Thermoset types: Recent patents for a same period 482

Future prospects for thermosets and composites 7.6.2 Analysis o f patents by reinforcement type

There are many patents concerning fibres but some relate to applications other than polymer reinforcement, for example building insulation. Figure 7.5 shows, for the same period, the recent patents per fibre type. Nanotubes and nanocomposites, particularly carbon nanotubes, are generating intense research activity whereas research is definitely weaker for nanofibres. Figure 7.6 shows, for the same period, the recent patents for the different nanotechnologies. Quartz fibre Boron fibre Silica fibre Aramid fibre Natural fibre Carbon fibre Glass fibre i

|

0

1000

Figure 7.5. Fibre types: Recent patents for a same period

Nanofibres

1 t

Nanocomposites

Nanotubes

I

0

1000

Figure 7.6. Nanoreinforcements: Recent patents 483


7.6.3 Analysis of patents by structure and process type

The analysis in this case is dubious because structures are confused with reinforcements and processes. For example, patents on films or other multi-layers spoil the laminate analysis. However, the high level of patents concerning nanocomposites and prepregs is obvious. On the other hand, the SMC/BMC patent level appears relatively low. The amount of patents concerning laminates, UD and filament winding seems to correspond to their level of distribution. Figure 7.7 shows recent patents, for the same time period, per composite structure and process. Lay-up Roving LFRP Mat i ,ent winding

II

Pultrusion

m

UD i RTM m SMC/BMC m Sandwich Prepreg Laminate locomposite Composites 0

Figure 7. 7.

500

Structures and processes: Recent patents

7.7 The immediate future seen through recent awards Recent awards from professional organizations, the professional press, engineers associations and so on reflect the most up-to-date technology. Among the numerous award-winning developments, we quote some examples: 9 Wing flap for regional and corporate aircraft (by Radius Engineering) made in carbon composite moulded by RTM. The elements are 3.6 m long and 0.7 wide. 9 Car rear floor of the Renault Megane 2 (by Inoplast) made in light SMC moulded in 1 minute. This concept leads to weight saving in the range of 25-30%, high design freedom and ease of dismantling. 484


9 9

9 9 9 9 9

9

9

9

9 9 9

9

Inlet manifold of the new eight-cylinder 7-series by B M W made of reinforced phenolic resin produced by Perstorp. Automotive body demonstrator (by Menzolit Fibron) made of an advanced SMC reinforced with carbon fibres leading to a weight saving of 60% versus steel with a high-quality surface finish. Tanks (by Covessa) capable of withstanding up to 100 bars made by welding three parts in glass fibre reinforced polypropylene (Twintex). Composite grid to replace steel reinforcement of precast concrete panels. Formula 1 shoes for Schumacher made in Nomex and carbon prepreg. The weight saving is 1.2 kg on each foot during 6g decelerations. Giant wind turbines: rotor 80 m in diameter, mast 120 m high. HTPC (Hybrid ThermoPlastic Composite) bumper beams made by Plastic Omnium are used on Pontiac Montana, Chevrolet Venture and Oldsmobile Silhouette by General Motors. Continuous woven fibres are overmoulded with a long or short fibre reinforced polypropylene to save weight (6 kg), enhance impact resistance (2040%) and integrate numerous functions such as reinforcement ribs. The process is fully automated. Rehabilitation of a steel truss bridge using a lightweight fibre reinforced composite deck. The dead load is reduced and the load ratings are doubled, allowing an increase of the maximum permissible weight. The cost saving is of the order of more than ~1 million. Controlled Energy Management Bumper Isolator (by Ford with LDM Technologies and Concept Analysis Corporation) includes a conical geometric design that enhances crash behaviour absorbing more energy in less space than polypropylene foam. Cost, weight, front and rear overhangs are reduced. Structural cargo boxes (by Ford with The Budd Company's Plastics Division) use an SMC instead of steel with a 20% weight reduction, elimination of the risk of the pickup bed rusting, and decrease in the number of pieces. Process to make powertrain throttle bodies with recycled polyamide from carpet (Ford with Visteon and Honeywell). Recycled plastic composite railroad crossties can save millions of trees, significantly reduce plastic landfill waste and cut maintenance costs. A plastic waste processor (by Carderock Division) has been developed to compress the Navy's plastic wastes into disks, solving the environmental and space problems from 600 kg daily plastic waste (20 m 3) per ship. Seaward International Inc and Carderock Division are developing a marine piling (The SeaPile) in structurally reinforced composite with a core made of these disks. Project to print organic transistors on plastic for electronic displays and circuits (by Sarnoff Corporation with DuPont de Nemours and 485


Company Central Research and Development). The goal is to develop materials, thin flexible plastic substrates, and methods for continuous high-resolution printing. 7.8 Environmental concerns 7.8.1 Recycling of thermosets and composites

From a practical point of view, the recycling of thermosets and composites is difficult and is constrained by: 9 The technical possibilities: the feasibility for handling mass quantities. 9 Economics: the final cost and the recyclate/virgin polymer cost ratio determine the success or failure of the method. 9 Environmental regulations" recycling must globally decrease the pollution balance versus tipping or landfill. 7.8.1.1. Collection and pre-treatment of wastes

The paths differ according to the source of the waste: 9 Manufacturing scrap" it is easy to sort and store them separately in good conditions (clean and dry). These wastes are not subjected to ageing and corrosion. 9 End-of-life products: this case is more difficult to treat. It is necessary to collect the products, to dismantle (if necessary) or to shred them before recycling. These pre-treatments are expensive. These wastes have been subjected for several years to ageing and corrosion and are often polluted. 9 Plastics incorporated into municipal solid wastes: these are burnt without special treatment. Figure 7.8 shows schematically the main paths leading to the recycling step.

I

Processing

I

Sorting

I

II I

Recycling

Collect

II unicipalso,i wastes ]

I

Sorting

I

I

Shredding

I Recycling I I ecycling I Figure 7.8. The waste collect and pretreatment

486

I Collect I Burning

Dismantling

Storage

I

I

Endoflif


7.8.1.2. The main recycling routes

The main recycling routes utilize: 9 Chemolysis" certain polymer families such as polyurethane are chemically depolymerized. This is the best recycling solution if the performances of the original material are to be recovered and if the recyclate is used in the same application. This is, technically and economically, a difficult method that is industrialized in few cases. 9 Mechanical recycling: shredding and grinding of polymer scraps allow a partial re-use in the original application but the recyclate level is low because of the decrease in performance. An extension of this principle is obtained by manufacturing other parts of lower performance, sometimes in another industry. 9 Solvent extraction of the polymer from shredder residue is only suitable for thermoplastics. 9 Thermolysis: gasification, pyrolysis.., to produce petrochemical feedstocks for steam-cracking or alternative fuels. 9 Co-combustion with municipal solid wastes. 7.8.1.3. Thermoset and composite specifics

The irreversible formation of a three-dimensional network during the curing of thermosets and the presence of fibres or other reinforcements are additional obstacles for waste recycling because it makes it impossible to: 9 Recover the original chemical state for thermosets. 9 Recover the original size of the reinforcements for all composites. The processing and/or the mechanical treatments involved in recycling break the fibres, foams, honeycombs, etc. 9 Return to the original properties. If we make the assumption that the difficulties of collecting, sorting, and cleaning are solved, some examples of recycling methods are listed below: 9 Polyurethanes can be recycled by: o Hydrolysis: The obtained monomers are identical to the original ones and can be reconverted into virgin polyurethane of the same performance as the original parts. o Glycolysis: The obtained monomers are different from the original ones and can only be used to partly replace virgin components in other types of polyurethanes. The virgin polyurethane obtained is different from the original material but the performances are satisfactory. 9 SMC and BMC can be recycled by mechanical shredding and grinding in three ways: o Micronized powders are added at the 5-15% level in new adapted formulations to replace mineral fillers. The density is slightly inferior and the performances are in a similar range. o Short fibre (few millimetres or less) recyclates used to reinforce polymers or concrete. 487


Long fibre (10 mm and more) recyclates used to reinforce polymers. 9 The rear leaf springs of utility vans made of continuous glass fibre reinforced epoxy are also recycled by mechanical shredding and grinding in two ways, to give either short fibre (few millimetres or less) or long fibre (10 mm and more) recyclates used to reinforce polymers. 9 The high mineral content of glass fibre reinforced plastics makes them a poor fuel because of the low organic content. However, they can be used in cement kilns where the glass goes into the raw materials and the matrix acts as fuel. 9 Unsaturated polyesters may be hydrolysed by high-temperature (300-500 ~ steam into phthalic acid, styrene, bituminous residue and glass fibres. For a given part, the adopted recycling solutions can belong to several categories of processes. For example, for bumpers out of SMC, six methods compete: 9 Grinding and re-use with virgin SMC. 9 Shredding and re-use of the fibrous recyclate to reinforce other polymers. 9 Shredding and re-use of the fibrous recyclate in the concrete industry. 9 Use in cement kilns. 9 Pyrolysis with production of gas, oils and tars. 9 Hydrolysis. o

7.8.1.4. Thermoset and composite recyclates: mechanical and calorific properties

The recycling treatments and the possible presence of pollution, paints or other surface products cause a reduction in the mechanical properties of recyclates, notably the impact strength and the ultimate characteristics. On the other hand, it is possible to upgrade the recyclate using additives or compatibilizing surface treatments. Table 7.3 (after figures from Owens Corning, N R C of Italy) shows the retention of certain properties versus the number of recycling cycles. Table 7.3 Processing and end-of-life scraps of glass reinforced polypropylene: property retention versus the number of recycling cycles

Retention, % Tensile strength Number of recycling cycles

488

Tensile modulus

Notched impact

Fibre length

Glassfibre reinforcedpolypropylene: Processingscraps

0

100

100

100

100

1

87

95

78

91

2

79

90

72

84

4

65

79

58

75

Future prospects for thermosets and composites Table 7.3 Processing and end-of-life scraps of glass reinforced polypropylene: property retention versus the number of recycling cycles

Retention, % Tensile

Bumpers

strength

Tensile modulus

Notched impact

Fibre length

Recycled end-of-life (10 years old) bumpers made of glassfibre reinforcedpolypropylene

New

100

100

100

Old

94

90

29

Recycled old

82

87

20

Recycled and upgraded old

91

90

74

For a high-performance glass fibre reinforced thermoplastic such as PEEK, the retention of modulus and strengths after two and four recycling cycles are in the ranges of 79-87 % and 76-84 %, respectively. Table 7.4 (after figures from Menzolit, SMC and Valcor) displays the effect of use of SMC/BMC recyclates on the properties of virgin SMC/ BMC or polypropylene. Table 7.4

Property retention (%) of BMC/SMC and polypropylene versus the level of BMC recyclate

Effect of BMC/SMC recyclate on

new BMCs and

SMCs

Recyclate, %

Tensile strength

Tensilemodulus

Notched impact

0

100

100

100

10

103

87-100

110-136

15

77-82

82-87

83-108

Effect of BMC/SMC recyclate on polypropylene compounds Neat

100

5% dough moulding compound (DMC) recyclate

100

100

69

150

31

5% glass fabric reinforced phenolic recyclate

109

290

61

24% surface treated DMC recyclate

109

172

31

24% surface treated glass fabric phenolic recyclate

235

283

96

Table 7.5 (after Neste) displays some calorific properties of plastic wastes compared to coal. The laminates and sandwich composites are handicapped by the low heat value and carbon content. Moreover, the laminates have a high ash content. Table 7.5

Comparison of the calorific properties of coal and plastic waste fuels

Coal

Polyethylene

Mixed plastics

Laminate

Sandwich

LHV (Low Heat Value)

25

40

32

17

19

Carbon

64

81

65

39

52

Ash

16

3

18

43

21 489


7.8.1.5. Recycling costs

In the most unfavourable case, the cost of recycling is a combination of the operations of collecting, dismantling, sorting, treatment and recycling. From an economic point of view, the cost assessment of the recyclate depends primarily on the price retained for the waste. The recycling cost is in the range of: . 4g0 per kg for a recyclate of processing scrap whose grinding cost balances the cost it would have been necessary to pay to eliminate it, 9 to more than ~gl.3 per kg if one has to take into account the combined costs of collecting, dismantling, sorting, grinding and recycling treatment. To decrease the dismantling and sorting costs of plastic parts it is necessary to anticipate these steps at the design stage: ,, To consider methods of assembly to make dismantling easier, 9 To standardize the plastics used. The monomaterial concept is attractive but is sometimes unrealistic for technical and economical reasons. As examples: 9 For a certain part with volumes of 3000 t/year, it was shown that the economic equilibrium was between 4g0.6 and 4g0.7 per kg for the recyclate. 9 For various methods and end-of-life products, the claimed costs vary in the range of @0.5 to 491 per kg. 9 For the solvent process, W i e t e c k - a commercial operator of a 4000 t f a c i l i t y - estimates that the process is economically viable for a polymer price exceeding ~gl per kg. 7.8.2 Sustainable standard and high-performance reinforcements

Natural reinforcements have been used for a very long time. 9 Wood flour was one of the first fillers used with phenolic resin. 9 Wood shavings are used in wood particleboards. 9 Short cotton and other cellulose fibres are commonly used in phenolic and melamine resins. The renewed interest in natural reinforcements may continue because: 9 Ecology is a sustainable policy. . The growing plastic consumption uses more and more glass fibres that the natural fibres can partly replace in general purpose composites. 9 Other industries processing natural fibres, such as the paper or flax industries, are seeking outlets for their by-products. 9 Natural fibres can bring specific properties. For example, a fibre developed by Impact Composite Technology absorbs the styrene in unsaturated polyester processing. 9 The development of new processing methods opens new applications such as the extrusion of "wood". 9 Biosynthesis allows production of high-tech reinforcements such as BioSteel. 490


Natural fibres were considered in sections 2.13 and 6.5 above, and we will only examine two prospective aspects of sustainable reinforcements here. "Extruded (or injected) wood": unlike the well-known phenolic resins reinforced with a low level of wood flour, "extruded or injected wood" is composed of a majority of cellulose (60% up to 90%, or even 95 %) and a small amount of polymer as binder. This binder can be synthetic or partially to totally natural. The US natural fibre and wood composite market was estimated at 340 000 tons in 2001 growing to just over 450 000 t in 2003, that is, roughly 1% of the total plastic consumption. According to Plastics Additives & Compounding, the market is predicted to grow to 635 000 t in 2006 or a 12% annual growth rate - dramatically higher than the average annual growth of plastics. Europe is not such an important market as the U S A because of the lack of available wood by-products and the lack of end-uses. Table 7.6 displays some properties of different "extruded or injected woods" compared to PVC. The value ranges are broad according to the various marketed techniques. As example, for an extruded wood grade with PVC binder a cost of 4E1 per kg is claimed. Table 7.6

Examples of properties of "extruded or injected woods" compared to PVC PVC

Density, g/cm 3

Extruded or injected wood

1.4

1.2-1.4

1.3-1.4


35-50

17-25

10-22

26-38


2.4-4

4-8

1-5

1.9-2.2


0.96-1

30-50

58-69


2.1-3.5

4-6

3


2-30

0.5-1

0.3-0.7

3-7

25

Charpy impact strength, kJ/m 2 Izod notched impact, J/m

20-110

24-57

BioSteel high-performance fibres: Nexia Biotechnology develops and produces these fibres made out of silk proteins secreted by transgenic goats. 25 % lighter than Kevlar, the failure energy would be much higher. The targeted applications are: 9 Medical devices 9 Industrial or sports ropes, fishing lines and nets 9 Polymer reinforcement for ballistic protection such as soft body armour, competing with Kevlar fibres. 7.8.3 Sustainable and biodegradable components for matrices

Like the synthetic polymers, natural and biodegradable matrices are principally thermoplastics, such as the following examples: 491


9 Polylactic acid (PLA) 9 Polyglycolic acid (PGA) 9 Polycaprolactone (PCL) 9 Polyhydroxyalkanoate (PHA) 9 Polyhydroxybutyrate (PHB) 9 Starch and other natural derivates of uncertain formula. These thermoplastics can be processed in nanocomposites and fibre reinforced composites. For thermosets there are developmental or industrial examples driven by automotive and combine harvester manufacturers (John Deere, Ford, etc.) such as: 9 RIM polyurethane components derived from starch, vegetable oils, soya, etc. 9 SMC polyester with 25% corn and soy-derived materials 9 Bicomponent casting resins derived from sugar, colza, starch, castoroil, etc. 7.8.4 Examples of sustainable composites

Here we outline just a few examples of sustainable composites: 9 Polylactic acid (PLA) reinforced with kenaf fibres developed by NEC for personal computer housings. With a 20% level of kenaf fibres, the main properties compete with glass fibre reinforced ABS but the cost is 50% higher. The flexural modulus is over 4.5 GPa and the H D T reaches 120 ~ 9 PLA/montmorillonite nanocomposites with a better heat resistance, a doubled modulus and an easier processing than the neat PLA. 9 VTT, a Finnish research centre, is developing fully biodegradable composites based on PLA reinforced with flax and other natural fibres. These composites can be used indoors in a dry environment. Outdoors there is a risk of degradation but this is sometimes an advantage, such as for agricultural products; using biodegradable composites reduces disposal costs. The tensile strengths are in the range of 70-80 MPa for a 40% by weight level of flax fibres.

References Technical guides, newsletters, websites

Borealis, Business Wire, Menzolit, NASA, Naval Research Laboratory, Neste, PRW, Owens Corning, SMC, Valcor, Zoltek. Reviews [1] Plastics Additives & Compounding (Elsevier Science) [2] PRW Newsletter (PRW.com & European Plastics News) [3] Reinforced Plastics (Elsevier Science) [4] Techniwatch (CRIF) Papers Zoltek, User's Guide for Short Carbon Fiber Composites, (June 2000), Zoltek Companies Inc, St Louis MO 63044, USA, www.zoltek.com 492

Conclusion

Today, plastics are an industrial and economic reality competing with traditional materials and in particular metals, of which steel is the most important. Roughly 150 million tons of plastics are consumed annually, which is: 9 Intermediate between those of steel and aluminium in weight, that is, roughly a sixth of the consumption of steel and six times the consumption of aluminium for recent years. 9 Higher than those of steel and aluminium in terms of volume in recent years: roughly 1.4 times the consumption of steel and 16 times that of aluminium. 9 Lower than those of steel and aluminium if we reason in terms of equal rigidity: equivalent to roughly 1% of the consumption of steel and half that of aluminium. The growth of plastics is significantly higher than that of steel. No engineer or designer can be ignorant of plastics, but the decision to use a new material is difficult and important. It has both technical and economical consequences. It is essential to consider: 9 The actual penetration of the material category in the industrial area 9 The functionalities of the device to be designed 9 The characteristics of the competing materials 9 The abundance or scarcity of the material and the process targeted 9 The cost 9 The processing possibilities 9 The environmental constraints. The intrinsic mechanical properties of plastics and composites are different from those of conventional materials. 9 Expressed in the same units, the hardnesses of engineering materials cover a vast range broader than 1 to 100. Plastics are at the bottom end of the range but are of a wide diversity and offer decisive advantages compared to metals, glass, ceramics, wood and others. 9 The properties of unidirectional composites in the fibre direction can compete with those of current metals and alloys. The highest


performance engineering plastics compete with magnesium and aluminium alloys. . Polymers are electrical and thermal insulators but have high coefficients of thermal expansion. 9 Polymers are not sensitive to rust but are sensitive to thermooxidation and, for some, to moisture degradation. 9 Polymers present a more or less plastic behaviour under stresses, leading to lower modulus and ultimate strength retentions, and higher long-term creep or relaxation when the temperatures rise. Thermosets, because of the crosslinking, cannot melt but decompose without melting as the temperature increases. . Many polymers, including the commodities, are resistant to the chemicals usually met in industry or at home and displace the metals previously used for applications such as domestic implements, gas and water pipes, factory chimneys, containers for acids and other chemicals. To compensate for their handicaps in terms of properties compared to traditional materials, polymers have effective weapons" 9 Design freedom. 9 Manufacturing in small quantities or large series of parts of all shapes and all sizes, integrating multiple functions, which is unfeasible with metals or wood. . Possibility of selective reinforcement in the stress direction. 9 Weight savings, lightening of the structures, miniaturization. 9 Reduction of the costs of finishing, construction, assembling and handling. . Ease and reduction of maintenance operations. . Damping properties. . Aesthetics, the possibilities of bulk colouring or in-mould decoration to take the appearance of wood, metal or stone, which avoids or reduces the finishing operations. 9 Durability, absence of rust and corrosion (but beware of ageing). 9 Transparency, insulation and other properties inaccessible for metals. Plastics and polymer composites are much more expensive than metals, even more specialized ones such as nickel. As for the specific mechanical properties, the high densities of metals modify the classification of the various materials. According to the cost per volume, plastics are competitive. Only the very high performance plastics or composites are more expensive than metals.

494

Conclusion

The links created between the chains of the thermosets limit their mobility and possibilities of relative displacement and bring certain advantages and disadvantages: 9 Infusibility, barrier effects. 9 Better modulus retention when the temperature rises. 9 Better general creep behaviour. 9 Simplicity of the tools and processing for some materials manually worked or processed in the liquid state. 9 Slower processing cycles. 9 More difficult monitoring of certain processes. 9 More difficult recycling. 9 Impossible to weld. The main advantages of polymer composites are: 9 High mechanical properties. 9 The possibility of laying out the reinforcements to obtain the best properties in the direction of the highest stresses. 9 The possibilities of repair: a significant advantage of composites. The development of composites is hindered by the difficulties in recycling, attenuated in the case of the thermoplastic matrices. The hybrid materials are often a good solution to take advantage of plastics and one or several other conventional materials. This principle, in more or less complex versions, is applied to the front-ends of recent cars, footbrake pedals, aircraft wheels, car doors, etc. The final choice of the design team may result from many iterations concerning the functional properties, the environmental constraints, the possibilities to produce the part in the required quantities and the price. The price considered may just be the part cost but can also include assembling, delivery, set up and end of life costs, taking account of durability, the savings in maintenance, etc. The future of plastics is promising thanks to the research and development efforts with significant new patents. The goals for future development are diverse" 9 Improvement of the cost/performance ratios. 9 Improvement of the immediate and long-term characteristics, to conquer structural parts. 9 Better thermal resistance. 9 Better weathering behaviour. 9 Enhancement of the colouring and surface aspect. 9 Improvement of the surface properties. 495


Adaptability of the grades, which must satisfy the requirements of the market and develop specific properties and better combinations of properties. 9 Halogen-free fire retardant grades. 9 Improvement of the adherence of paints, printing inks, adhesives. 9 Better performance, particularly impact resistances, at low temperature. 9 Improved ease of processing. 9 Improvement of the mould productivity. 9 Automation of the process equipment. 9 Better control of the processes by SPC. 9 Development of new manufacturing methods. On-line compounding to reduce costs and thermal degradation. 9 Hybrid associations with non-plastic materials. 9 Use of wastes and recycled materials to satisfy the environmental requirements and lower the costs. 9 Management of recycling, starting with the design 9

All the developmental routes are being investigated: 9 New materials are being introduced, including: - new polymers. For example, Dow is starting to market cyclic resins developed by Cyclics Corp. and new reinforcements ranging from the more-or-less conventional to the highly sophisticated, such as carbon nanotubes. 9 Evolution of processing: globalization, automation, industrialization, simplification, low-cost tools. 9 Popularization of high-performance products such as carbon fibres and 3D reinforcements to compete with their 2D counterparts. 9 Sustainable standard and high-performance reinforcements, sustainable and biodegradable components for matrices, sustainable composites. 9 New combinations of known products or techniques such as the low weight reinforced thermoplastics (LWRT). -

The above comments are only a superficial overview of the immense possibilities of these young polymer materials that could be 'The Materials of the 21st Century'.

496

Index

A

C

accelerated ageing 148, 160 adaptability 467 additive costs 52 adhesive bonding 340, 441 aeronautics 109, 113, 119, 128, 121,133, 135, 137, 227, 253,277, 301,318 aerospace applications 77 ageing 189, 213, 230,243,259,282,305,320 agricultural equipment 122 airex r82 397 aluminium honeycombs 400 amino resins: melamine (MF) 239 analysis of patents 482-484 anti-abrasion 84 anti-corrosion 82, 84, 101,122, 207 equipment 84 anti-wear 108, 253 aramid fibres (AF) 128, 381 aramid honeycombs 399 arc resistance 154 armaments 76, 128, 130, 137, 253, 277,290 art 90, 120, 208 assembly 441 costs 61 ASTM D257 153 automated lay-up 429 automotive 63, 95, 111,114, 131,136, 205,226, 254, 277, 323 industry 63 awards 484

calorific properties 488 carbon fibres (CF) 129, 379, 483 hybrids 387 carbon nanotubes (CNT) 476 cases 87 casting 336, 420 centrifugal moulding 143, 4301 chemical 190,214,230,244,260,284,306,325,327 behaviour 162 resistance 152 clamping 341 Clash & Berg test 149 co-moulding 436 coating application 95, 187 coefficient 13349 cold compression moulding 424 collection of wastes 486 comfort 70 composite 49, 81, 68, 81 characteristics 443 insert moulding 436 matrices 350 mechanical performances 346 processing 25,359, 413 properties 370, 389 compounding integrated 475 compression 435 moulding 331,419 properties 156 set 161,189 transfer moulding 332, 425 conductive composites 462 consumption trends 48, 472 continuous sheet moulding 144 continuous stratification 433 continuous use temperature (CUT) 146 Core-Cell 395 corrosivity 306 cost 185,205,226,252, 276, 299,317,358,360, 362, 365 per volume of various materials 13 per weight of various materials 12 savings 372, 473 creep 151,161, 189, 212, 230, 257, 281,320 compression set 304

B basic principles 344, 443 bedding 74 biodegradable components for matrices 491 BMC 138, 404 body 65, 85, 87 boron fibre hybrids 387 brittle point 148 building and civil engineering 70, 92, 98,105,118, 136, 139, 206, 227, 300 building furniture 111,254 bulk moulding compounds (BMC) 407


crystallization 160 test 149 cyanate esters (Cy) 120, 317

D damping 65, 70, 85 decoration 90, 120, 208, 215,233,344 dicyclopentadiene (DCPD) 121,322 dielectric strength 153 dimensional stability 213,230, 243,259, 282, 305, 320, 325 dough moulding compound (DMC) 408 durability 10 dynamic fatigue 189, 213, 230, 259, 282, 305,320 dynamic mechanical properties 161

E earth-moving equipment 122 economic requirements 21 ecycling of polymers 29 effect of short glass fibre 376 effect of the fibre level 445 effect of the fibre nature 445 elastic modulus 150 elastomer application 94 187 electric household appliances 88, 105, 118, 300 electrical properties 153, 163, 193,215, 232, 245, 265,289, 309, 320, 325 electricity 86, 94, 104, 106, 115,207,227,241,253, 277,318,324 electronics 86, 94,100,110,121,127,207,253,277, 318,324 environmental concerns 486 environmental constraints 29 environmental requirements 22 environmental stress cracking (ESC) 153 epoxide resins 108 epoxides 251 epoxies 352 epoxy resins (EP) 251 european market 44 external elements 65 extrusion 335,436, 437

F fatigue 152, 161 fibre 241,370 composites 450 filament 437 winding 142, 429 filled resin 420 finishing operations 439 fire resistance 193, 215,232, 244, 265,289, 309, 320, 324 flammability 154, 163 flexible foams 195, 289, 309 flexural properties 156 fluid contact behaviour 162 fluoroplastics 363 fluorosilicones (FMQ, FVMQ or FSI) 297 498

foaom 193,233,245 application 92, 186 foamed composites 458 foamed epoxies 265 foamed matrix composites 459 foamed polyimides 289 foamed silicones 309 formworks 85, 87 frames of machines 85 friction 212, 230, 243, 257, 280, 304, 320, 325 furan 326 furane resins 122 furniture 74, 92, 94, 101,126, 135, 141,207

G garden equipment 122 gardening equipment 324 gas permeability 154, 162 gehman test 149 glass fabric 349 glass fibre plastics 376 glass fibres 123,373, 480 glass mat thermoplastics (GMTs) 409 global plastics industry 32 glue and adhesives 112, 255 GMT sheets 434 guarantee 467

H hand lay-up 140, 415,417, 418 HDT 160 health 112, 254, 119, 301 heat behaviour 327 heat deflection temperature (HDT) 147 high-energy radiation 260, 284, 320 high-performance reinforcements 490 high-pressure injection moulding 426 honeycombs 399 hot compression moulding 424 household appliances 107, 227,241 housing equipment 324 humidity 162 hybrid 16 135, 474 composites 461 materials 19 processing 28

IEC 93 153 immersion 152 impact test 150, 159 importance of the various processing modes 42 industrial fibres 388 industry 92, 94, 107, 115, 122, 241 infusion process 422 initial behaviour 209, 228,242, 255,278, 302, 318, 324, injection 420, 435 moulding 334

Index

insulation 85, 87 integral skin foams 194 interlaminar properties 158 interlaminar shear strength (ILSS) 150 intermediate semi-manufactured composites 411 materials 404 intrinsic mechanical properties 4 ISO standards 155, 196, 233, 246, 310, 380, 370, 373,377

method for strength estimation 348 mineral fibres 387 molecular reinforcement 477 moulding of test specimens 155 MQ 138

N nanocomposites 444 nanofillers 402, 477 nautical sports 81 new high performance polymers 481 new processes 475 north american market 47

L laminates 227 law of mixtures 349 leisure 94, 95,112, 254, 324 leisure parks 208 LFRT 449 light resistance 162 lighting 70 liquid crystal polymers 365 liquid injection moulding (LIM) 336 liquid thermoset processing 336 loading direction 348 long fibre reinforced plastics 449 long-term behaviour 209, 228, 243,255,279, 303, 319,324 long-term light 152 long-term mechanical properties 151 long-term properties 160 low temperature 160 behaviour 148, 210, 243,257, 280, 304, 319, 324, 475 low-cost tool 475

M machining 440 main composite families 91 "~ain processing methods 136 malP., recycling routes 487 main reinforcements 123 main thermoget- families 91 maintenance costs 61, 62 marketing requirements 22 market 472 shares 34, 36, 38 material costs 12, 473 selection 164 upgrading and competition 476 mechanical assembly 341,441 mechanical elements 67 mechanical industry 118, 300 mechanical properties 4, 149, 155, 189, 211,229, 243, 257, 280, 304, 319, 325, 327, 488 mechanics 126, 141 melamine 105,234 metal consumption 2 metallization 440

O office automation 88, 114, 120, 277, 302 offshore 81 operating cost 21,467 optical properties 155,164,189,211,229,243,257, 280, 304 optoelectronics 118, 300 outdoor furniture 75 overbraiding 432 oxygen index 154, 163

P packaging 90, 95, 107, 122, 208, 241,324 passenger compartment: 67 patents 482 PBO fibres 388 phenolic resins (PF) 103, 223,254, 351,434 phenylene polysulfide 362 plastic 20 consumption 2 costs 50 properties 146 plywood 227, 400 PMQ 138 polution 29 polyacetal (POM) 361 polyacrylics (PMMA) 361 polyamide 360, 365 polycarbonate 362 polycyanates 120, 317, 354 polyetheretherketone 364 polyetherimide 365,397 polyethersulfone foams 397 polyethylene (PE) 358 fibres 388 foams 394 polyimides (PI) 113, 275, 353 polymer composites 18,477 polymethacrylimide 396 polyphenylene ether (PPE) 362 polyphenylene oxide (PPO) 362 polypropylene (PP) 358 foams 394 polysiloxanes 138 polystyrene 359 foams 393 499


polysulfone 364 polyurea 91, 95, 187 polyurethane 91,184, 354 foams 392 polyvinyl chloride (PVC) 358 polyureas (PUR) 184 powder moulding compounds 216 pre-treatment of wastes 486 precision of the moulded parts 165 premix 408 prepreg applications 143 prepreg draping 427, 437 press fitting 341 primary processes 25 processing costs 54, 474 property of RRIM, SRRIM 458 protection properties 108, 253 PTFE fibres 388 publicity 208 pullwinding 432 pultrusion 141,431,437 PVMQ 138

R raw material 196, 216, 233, 266 costs 51 reaction injection moulding (rim) 337 reaction of reinforced resin 420 recycling 486 recycling costs 490 reduction factor 348 reduction of production costs 467 refrigeration 88 reinforcement 346, 347,348, 370 costs 53 form 348 relaxation 151,161 repairing composites 442 requirements of the market 466, 473 RFI 422 RIFT 422 rigid foams 195 rigid PVC foams 391 RIM application 93, 186 riveting 341 rohacel1396 rotational moulding 338 RRIM 420, 458 RTM 139, 423 S safety 83 sandwich composites 133, 437, 457 sandwich properties 401 sandwich technology 390 screwing 341 SCRIMP 422 sealing application 85, 95, 187 secondary processing 25, 27 self-reinforced polymers 133, 412 500

semi-rigid foams 195 shear properties 157 Sheet Moulding Compound (SMC) 405 shipbuilding 93, 100, 112, 122, 135,140, 207,254 short aramid fibres 448 short carbon fibres 447 short fibre composites 445 short glass fibres 446 SI 138 significant parameters 445 silicones 116, 355, 138 sliding 84 SMC 138 smoke generation 163 smoke opacity 155 snap-fit 341 solid thermoset processing 330 some weaknesses of the polymer materials 22 soundproofing 70, 107,241 space 76, 133, 135, 290 specific mechanical properties 7 sports 89, 93, 94, 95, 112, 254, 324 spray lay-up 140, 341,416, 417 spring work 341 SRRIM 420, 458 stainless steel fibres 387 street furniture 75 stress and strain at yield 150 structural applications 86 structural foamed epoxies 265 structural foamed polyurethane 195 structural parts 65 structure of the plastic processing industry 49 styrene-acrylonitrile foam 395 surface finishing and painting 439 surface resistivity 153 survey of main markets 63 sustainable components for matrices 491 sustainable composites 492 sustainable natural fibres 132, 385 sustainable standard 490 syntactic foams 266, 290, 310, 318, 320. 398, 460 T tape winding 437 technLal requirements 21 tensile properties 155 tension set 161 textile fibres 387 the fibre lengths 349 thermal and electrical properties 8 thermal behaviour 146, 187, 209, 228, 242, 255, 278, 302, 318, 324 thermomechanical properties 160 thermoplastic 357 composites 136, 434 matrix properties 365 polyesters 360 thermoset 16, 48, 322, 350 assembly 340

Index

composites 166, 414, 488 machining 339 matrix properties 356 processing 23 torsion properties 158 toxicity 29 trade name 197,217,235,247,267, 290, 310, 321, 325,327, 378, 381,383 transmission system 86 transport 63, 95,102, 104, 107, 120, 123,134, 137, 140, 208, 226, 241,302

V

U

W

UL temperature index 147 UL94 ratings 154 ultimate stress and strain 150 under-the-hood compartment 67 unidirectional reinforcement 347 unsaturated polyester 349 unsaturated polyesters (UP) 95,203, 350 urea-formaldehyde (UF) 239 urea-formaldehyde resins (amino resins) 105 UV resistance 152

water sports 100, 112, 207, 254 weathering 189, 213,230, 243,283,306 weight reduction 82 whiskers 387 wire and cable insulation 87 wood 400

VacFlo 423 vacuum bag moulding 417, 422 vacuum impregnation moulding 422 vacuum outgassing 289, 3200 vacuum technology 116, 278 vapour permeability 162 VARI 423 VARTM 422 vicat softening temperature 148, 160 VMQ 138 volume resistivity 153

Y yield point 150

Z ZMC 138

501

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