Guide to Thermoplastic and Thermosetting Polymers for Composites Dr. Ian Hamerton

1. Thermoplastic and Thermosetting Polymers for Composites Dr Ian Hamerton Chemistry School of Biomedical and Molecular Sciences University of Surrey

2. Definition of a Composite Thermosetting polymers Thermoplastic polymers Thermoplastic processing Use of Composites in Aerospace Performance Criteria Application of LCA to composites Conclusions Questions Outline of Presentation

3. Composite A multi-phase material in which the properties of a continuous phase (matrix) are enhanced by distributed sheet-like, fibrous or particulate fillers

4. Epoxy (common, industry standard, versatile) Vinyl esters (composition, cost properties between epoxies and unsaturated esters) Unsaturated polyesters (cheapest, good properties at lower temperature, large components/volume production) Phenolics (lower mechanical properties, retain to high temperature, no toxic flammables) Polyimides (expensive, but high performance) Bismaleimides (good hot/wet properties, brittle, cheaper than some polyimides) Cyanate esters (low loss properties, relatively expensive) Common Thermoset Polymers

5. Epoxy Selected high performance thermosets Polyimides Bismaleimides Cyanate esters Phenolics Unsaturated polyesters Vinyl polyesters

6. Can offer Variety of physical forms and viscosities Wide choice of curing systems Latitude with processing conditions Low cure shrinkage Good chemical resistance Good mechanical properties Good fibre/reinforcement adhesion Thermal stability over wide temperature range Good resistance to moisture But… Often limited outlife Usually need to be toughened Pose significant recycling problems Thermosetting Polymers

7. Selected high performance thermoplastics

8. Will soften above Tg for shaping and harden in this form on cooling Can offer Better resistance to moisture and various industrial solvents than thermosets Superior flexural and impact properties to thermosets But… Poorer abrasion and dimensional stability to thermosets No apparent advantage in static properties or fatigue Higher processing temperatures than most thermosets (generally above 300oC) Compression strength may be inferior Thermoplastic Polymers

9. Tg/oC Tproc/oC Poly(amide-imide)a 275 345-355 Polyarylethersa220-260 310-345 Polyethersulphonea220 300-310 Poly(arylene sulfide)a200-210 345 Polyetheretherketonec140-145 340-350 Polyphenylenesulfidec85-95 330 Poly(arylene ketone)c200-210 370-415 Polyimidea,c250-280 350-360 Tg = Glass transition temperature a = amorphous Tproc = Processing temperature c = crystalline Thermoplastic matrices

10. Thermoplastic processing methods • Autoclave consolidation • Press forming (rubber assisted punch or hydro forming) • Double diaphragm forming • Pultrusion • Roll forming • Filament and tape winding

11. Aerospace Applications Combinations of thermoplastics and thermosets

12. Aerospace Applications

13. Trade offs as composite Property T/sets T/plastics Formulations complex simple Melt viscosity very low high Fibre impregnation easy difficult Prepreg tack good none Preprepg drape good none to fair Prepreg stability poor excellent Processing cycle long short to long Processing T/P low/moderate high Fabrication cost high potent. low Mech. Properties fair to good fair to good (-54 to 93oC, hot/wet) Environ. Stability good unknown Solvent resistance excellent poor to good Damage tolerance poor/good fair/excellent Database very large small

14. Initial preparation Formulation Processing Lifetime(s) Recycling potential LCA should address:

15. Thermosets High monomer cost Long processing cycle Storage of prepreg (refrigeration) Repair (poor damage tolerance) Poor recycling potential Thermoplastics High melt viscosity/impregnation High polymerization temperatures Conclusions – potential hotspots

16. Any Questions?