Recent Developments in High-Performance Thermoplastic Composites

1. Recent Developments in High-Performance Thermoplastic Composites Allan Murray, Ecoplexus Inc. Klaus Gleich, Southern Research Institute ACCE 2003

2. Introduction Materials Process Technology Applications Overview

3. Why Use Composite Materials ?

4. Benefits Unique properties Vibration dampening Light weight Potential for low cost Shelf life Recyclable Durability Fatigue Corrosion Toughness Limitations Cost Materials Manufacturing Tooling Design know-how Manufacturing know-how Use temperature Thermoplastic Composites

5. Many Polymer Options Polyethylenes Polypropylenes Nylons Polycarbonates Acrylics Polyesters Polyimides Polysulfones Polyketones Polyurethanes the list continues Many Property Options ultimate strain > 100% no microcracking no delamination dampening no water uptake low dielectric properties melt formable weldable elastomeric - plastic - elastic behavior the list continues Thermoplastic Composites

6. Cost Challenge

7. Properties are fiber dominated Oriented long or continuous fiber reinforcement High volume fiber fraction (up to 65% by volume) Key benefits: Reducing thermal limitations (e.g. creep) caused by the TP matrix system Reducing costs and weight and retaining toughness, formability, weldability, short cycle times, recyclability benefits of the thermoplastic matrix High-Performance Thermoplastic Composites

8. Thermoplastic Materials

9. GMT (Glass Mat Reinforced Thermoplastics) Pultruded Products LFT (Long Fiber Reinforced Thermoplastics) CFT (Continuous Fiber Reinforced Thermopastics) Wire coated products Commingled fibers Powder coated materials Film sticking Slurry processes Commercial Materials

10. Long-FiberThermoplastic Composites • New Hot-melt Process Produces Fully Wet-out Composite Products • Wide Range of Polymers and Fibers • Continuous Tape and Rod Products • Discontinuous Products with Any Fiber Length • Glass Products <$1.00/lb • Carbon Products <$8.00/lb

11. Pilot Production for Thermoplastic Composites

12. Short Fiber, Long Fiber and Continuous Fiber Composites Typical short fiber thermoplastic material, granules with fiber length of approx. 2 to 4 mm, resulting fiber length in a part of approx. 0.4 mm Long fiber thermoplastic material, pellets of ½” and 1 “ fiber length, resulting fiber length in a part of approx. 4-6 mm in injection molding and approx. 20 mm in compression molding Continuous reinforced thermoplastic material, tape used for woven sheets (thermoforming), filament winding or pultrusion

13. Fiber: E-glass, S-glass, Carbon, Aramid, polymer fibers Matrix: PE, PP, PA (6, 6/66, 12, …), PET, PBT, PC, PEI, PPS, SMA, blends, … Fiber content: 20% - 60% standard, some up to 84% Product forms: Tape, pellets (0.5”, 1”), woven tapes more complex textile structures in development Typical Pultruded Prepregs

14. Twintex - The Commingling Concept Consolidated Composite Twintex® Prepreg Temperature + Pressure Source: Vetrotex

15. Twintex – The Commingling Concept E Glass adapted sizing Plastic filament Additives : - coupling agent - UV stabilizer - natural or black Source: Vetrotex

16. Twintex – The Manufacturing Process Extruder Bushing Glass TP Commingling Roving Source: Vetrotex

17. Fiber/matrix combinations: E-glass/PP, E-glass/PET Fiber content: 60 % and 75 % by weight Product forms: Roving, fabric, pellets Twintex - Commingled Fiber Products Twintex • Limitations: • Matrix material must be usable for a fiber spinning process  limitations in MFI/viscosity, additive type and additive content

18. Vetrotex Twintex Physical Property Data Source: Saint-Gobain Vetrotex, “Twintex PP and PET Mechanical Properties (non standard)”

19. Powder Impregnated Prepregs – The Hexcel TowFlex-Technology Fluidized Bed Powder Coating Chamber Fiber Creel Racks Take-up System Puller IR Oven To Weaving To Tapes To Pellets Charged Resin Powder Source: Hexcel

20. Typical fibers: Carbon, E-glass, S-glass Typical resins: PP, PA6, PPS, PEI, PEEK Typical product forms: Flexible Towpreg Woven fabric Braided Sleeving Unidirectional Tape Hexcel TowFlex TowFlex Glass Carbon

21. Hexcel Towflex Physical Property Data Source: Hexcel Composites (March 2003) www.Hexcel.com

22. Process Technology

23. Current Composite Materials and Processes

24. Composite Performance versus Fiber Length Fillers Short Fiber Continuous Long Fiber Source: OCF

25. Stress is transferred to the fibers - the structural members of the composite Long fibers create a “skeletal structure” within the molded article that resist distortion and provide unmatched strength, toughness, and overall performance The Long Fiber Advantage Source: Ticona

26. In continuous oriented fibers the load is ultimately ‘fully’ transferred to the fiber As a result tensile creep is limited in fiber direction Continuous Fiber Advantage

27. Low volume manufacturing processes Discontinuous processes Thermoforming Thermoplastic S-RIM, RTM and VARTM Thermoplastic filament winding Vacuum bag molding Net shape preforming (modified P4) Manufacturing Processes for High-Performance TP-Composites

28. High volume manufacturing processes Discontinuous processes Injection molding with LFT-pellets and concentrates (high performance resin/fiber combinations) Inline compounding (high performance resin/fiber combinations) Back molding / local reinforcement Compression molding LFT-pellets and concentrates (high performance resin/fiber combinations) Inline compounding (high performance resin/fiber combinations) Back molding / local reinforcement Stamp forming Preheated preforms Matched metal tools Potential to manufacture very thin sections (0.5 to 1 mm) Drapable material required Continuous processes Pultrusion LFT-extrusion Manufacturing Processes for High-Performance TP-Composites

29. Materials used for liquid molding processes Cyclics Reactive nylon Fulcrum Requirement for these materials Viscosity less than 3000 mPa.s (cP) (better less than 1000 mPa.s (cP)) Materials Used For Liquid Molding Processes

30. Cyclic form of PBT, PET, PC and others Only PBT commercial available Based on a ring shaped cyclical form One or two part systems Solid at room temperature – low viscosity resin at elevated temperature (approx. 150 cP) Polymerize into the Polymer using a catalyst Isothermal process Typical process temperature: 180 – 200 oC Cyclics

31. Reactive Nylon For more information see presentation on “Reactive Thermoplastic VARTM/RTM/S-RIM”

32. ISOPLAST matrix (Dow proprietary engineering thermoplastic polyurethane) Thermoplastic viscosity issues addressed by ability to reverse polymerization in the melt stage, reducing viscosity to ensure good impregnation Repolymerizes upon cooling, retaining traditional thermoplastic composite advantages High impact resistance Recyclability High elongation to failure (~2.5%, versus ~1-1.5% for thermosets) Zero-emissions processing Fulcrum is the combination of ISOPLAST and pultrusion, with specific hardware design Provides 10-fold line speed improvement over typical thermoset pultrusion lines Allows thermoforming, welding, and overmolding of finished pieces Fulcrum Thermoformed Fulcrum Components Figures from “Fulcrum Thermoplastic Technology; Making High-Performance Composite via Thermoplastic Pultrusion” Dow Plastics, January 2000

33. Dow Fulcrum Physical Property Data 45v.% and 55v.% data from Matweb.com 76.6wt.% and 66wt.% data from “FULCRUM: Thermoplastic Composite Technology, Making High-performance Composite via Thermoplastic Pultrusion” Dow Plastics, January 2000

34. Similar the thermoset process Reaction of at least two components creates a thermoplastic resin that can be melted, pre-shaped, welded, … Low viscosity is required Possible materials: Nylon, TPU, C-PBT (Cyclics) Reactive Thermoplastic VARTM/RTM/S-RIM

35. Reaction can be stopped or made incomplete by Moisture Chemicals in fiber sizing Most of the thermoplastic compatible sizings are not developed for such type of processes Availability of compatible sizings in form of fabric is very limited Oxygen Only limited support of material manufacturers Material costs (in case of c-PBT) Problems Connected With Thermoplastic RTM

36. Finished Product Thermoforming Heat in Oven Operation Thermoforming

37. Weight performance: Good weight/performance ratio for fabric reinforced sheets due to continuous fibers Reduced weight/performance ratio for extruded sheets depending on the resulting fiber length Design flexibility: Limited, especially for complex geometries Simulation tools available Processability: Stabilization against oxidation necessary Fiber disalignments with continuous fibers possible depending on geometry, material, tooling and process conditions Recyclability: High rate of production scrap (fixation) No direct recyclability Use in other processes like plastication of regranulation Thermoforming

38. Weight/performance: Excellent Design flexibility: Limited to preforming capability, flow length and flow behavior of the resin Processability: Reaction can be sensitive to moisture and fiber sizing Recyclability: Production scrap due to preforming step depending on preforming method No direct recyclability; can be used in other processes TP S-RIM, RTM, VARTM

39. Weight/performance: Excellent Design flexibility: Limited to symmetric parts that can be wound on a mandrel Processability: Higher oxidative stabilization required Recyclability: Low rate of production scrap No direct recyclability Scrap can be used in other processes TP Filament Winding

40. Weight/performance Excellent due to continuous fiber reinforcement Design flexibility Limited to drapability and to the posibility of manually lay up Processability Higher void content due to low pressure consolidation Using autoclave to reduce void content Often fiber disalignments Recyclability High rate of production scrap possible depending on the size of the material sheets and the part geometry No direct recyclability Scrap can be reused in other processes Vaccum Bag/ Hand Lay-Up

41. Weight/Performance Lower end of thermoplastic composites due to reduced fiber length in the final part Improvements possible by using local reinforcements (using pultruded sections, sheets or tapes of continuous composites  localized strengthening and stiffening, reduction of warpage) Design Flexibility High Flow channels and positions of gates have to be carefully designed Processability Highly stable Recyclability Low production scrap rate Can be reused in the same process LFT-Injection Molding

42. Weight/Performance Medium Retaining fiber length gives excellent properties for a random oriented material, but is lower than using a fabric Local reinforcement or fabric reinforced GMT improve it (using pultruded sections, sheets or tapes of continuous composites  localized strengthening and stiffening, reduction of warpage) Design flexibility High Special simulation tools available Processability Very stable process Recyclability Some production scrap due to trim operations Scrap can be added and reused in the same process (GMT only sheets can be reused in the same process, but not recommended) Compression Molding

43. Self-reinforced polypropylene Consists of “hot compacted” polypropylene fiber or tape Surface of tape or fiber melts during compaction to form the “matrix” that binds the directional elements together Oriented morphology provides over six-fold increase in tensile strength and nearly 5-fold increase in tensile modulus over isotropic polypropylene, with ~2% weight penalty Nearly doubles tensile strength of 40% random mat short glass polypropylene, with comparable modulus and 22% weight savings Elimination of glass reinforcement has several advantages: Increased recyclability Reduced weight Lower temperatures and pressures for thermoforming Reduced irritation in the workplace High strain to failure, with good impact strength Curv Data from “A New Self-Reinforced Polypropylene Composite” Jones, Renita S. and Derek E. Riley

44. Curv Physical Property Data from BP document “A New Self-Reinforced Polypropylene Composite” Jones, Renita S. and Derek E. Riley, 2002

45. Weight/performance Good to excellent due to continuous reinforcement Design flexibility Low design flexibility Limited to constant cross sections, but can be shaped (pull/press) Processability Only limited experience available Depends on stabilization of the material as well as used material form Recyclability Low rate of production scrap expected No direct recyclability Can be used in other processes Pultrusion

46. Weight/performance Medium weight performance Depends on retaining fiber length Design flexibility Low design flexibility Limited to constant cross sections Can be post shaped or pull formed Processability Not a lot of experience A stable process is expected using the right die design Recyclability Low rate of production scrap Can be reused in the same process LFT-Extrusion

47. Economics

48. Applications

49. Aerospace and defense: Radomes, wing and fuselage sextions, anti-ballistics Infrastructure and Construction Window profiles, rebar, beams, structures, composite bolts Consumer / recreational Orthotics, safety shoes, sporting goods, helmets, personal injury protextion, speaker cones, enclosures, bed suspension slats Auto and truck Bumper beams, skid plates, load floor, seat structures Transportation Railcar structure, body structure and closures Energy production and storage Oil and gas structura tube, wind turbines Applications For High-Performance Thermoplastic Composites

50. BMW M3 Bumper Beam • - Beam and crush columns • manufactured using • Hexcel TowFlex PA6 • Parts welded by high • frequency vibrational • welding • 2 versions: • Standard M3 based on glass • fiber reinforcement • (approx. 40 cars / day) • M3 CSL (limited to 1600 • total) using Carbon fiber • reinforcement Source: Jacob Kunststofftechnik GmbH & Co. KG www.jacob-kunststofftechnik.de