1ENG 4793: Composite Materials and Processes1Combining Thermoplastics withReinforcing Fibersver 1ENG 4793: Composite Materials and Processes2Outline• Issues• Approaches– Short Fibers– Long Fibers– Continuous Fibers• ConclusionsENG 4793: Composite Materials and Processes3Issues• Controlling fiber orientation• Obtaining high fiber content• Achieving good fiber wetting• Preserving fiber length• Avoiding polymer degradationENG 4793: Composite Materials and Processes4Short Fiber Processes• Extrusion Compounding Dominates– Benefits:• Low cost (< $ 0.20 per kg)• High volume (> 100 kg/hour)– > 1 Billion kg/year• Available as “standard” pellets (3 mm length)ENG 4793: Composite Materials and Processes5Short Fiber Processes• Extrusion Compounding Dominates– Limitations• Low fiber volume (< 30 vol % typically)• Random fiber orientation• Significant fiber breakage– Input: 3 mm fibers– Output: < 1mm fibers (but L/D still > 40)ENG 4793: Composite Materials and Processes6Short Fiber Processes• Extrusion Compounding Dominates– Typical results:• Modulus > 1.5 - 3 X• Tensile Strength > 1.5 - 3 X• Impact Strength often decreases• Heat Distortion Temperature– crystalline polymers much higher– amorphous polymers slightly higher– Many injection molded products2ENG 4793: Composite Materials and Processes7Short Fiber ProcessesThermoplasticPelletsChopped FibersExtruder Strand DieWaterBath PelletizerPelletsENG 4793: Composite Materials and Processes8GMT ProcessHeatingHeatingCoolingCoolingExtruderCutterGMTGlass mat coilDouble Belt PressENG 4793: Composite Materials and Processes9Electrostatic Fluidized Bed PowderCoaterDense phaseWinderLean phaseAir spreaderLe t- of fTensioncontrolFluidized bedAirElectrostatic ChargeOvenENG 4793: Composite Materials and Processes10Flexible Powder Coated TowDevelopment• Complaints about APC (boardy, expensive)• FIT process developed (flexible, expensive)• GT process developed (flexible, cheap?)• Military interest in TPC fades• Prince Vortex racquet commercialized• Custom Composites (CCMI) started- GT process, focus on sports- GT process dropped• Applied Fiber Systems acquires CCMI- Fast, reliable production achieved- K2 mountain bike successful- Industrial applications multiplying1985199019952000ENG 4793: Composite Materials and Processes11Long/Continuous Fiber Processes• Extrusion coating dominates– Higher conversion cost (> $ 1.00/kg)– Low volume (< 100 kg/hr) (< 1 billion kg/yr)• 6 and 12 mm pellets common– Designed for injection molding– Longer pellets harder to mold and littlebenefit• Other shapes:– Ribbon, Tape, BMC, ProfilesENG 4793: Composite Materials and Processes12Long Fiber Extrusion CoatingProfilesCutterPelletsCoolerRovingsThermoplasticPelletsCounter Flow Die ( USP 5,176,775 )3ENG 4793: Composite Materials and Processes13Long Fiber Extrusion Coating• Coating Limitations- Intermediate fiber volume (20 to 50 %)- Low viscosity thermoplastic- Need fiber spreading- Time to permeate fiber bundles• Injection Molding Limitations- Significant fiber breakage- input: 12 mm fibers- output: 0.5 – 3 mm fibersENG 4793: Composite Materials and Processes14Long Fiber Extrusion Coating• Typical results*:- Modulus > 3 – 6X- Tensile strength > 2 – 5X- Impact Strength > 2 – 10X- Heat Distortion Temperature > 10 – 100oC- (amorphous – crystalline)* Based on injection moldingENG 4793: Composite Materials and Processes15Alternative Long Fiber Processes• Lamination Approaches- Extrusion- Wet laid-Dry laid• Flexible Fiber Bundle Approaches- Commingling of fibers- Powder coatingENG 4793: Composite Materials and Processes16Dry GMT ProcessGlassFiberRovingChop MatLaydownCoaterThermoplasticPowderLaminatorGMT WebENG 4793: Composite Materials and Processes17Laminated Panel Products• Truck trailer liners (tough)• Bus panels (tough)• Doors ( tough, insulating)• Floating piers (light, water resistant)• Form boards (light, chemical resistance)ENG 4793: Composite Materials and Processes18Compression molded products• Mostly automotive, e.g.:– bumper beams (good impact)– battery trays (chemical resistance)– seat structures (impact, fatigue)– sound insulation (damping)– instrument panels (complex shape)4ENG 4793: Composite Materials and Processes19Thermoformed Products• Shipping containers (light, tough)• Luggage racks (tough, stiff)• Pallets (tough, stiff, moisture resistant)• Flooring (tough, resistant)• Boats (moisture resistant, tough, stiff)• Concrete form boards (moistureresistant, tough, stiff)ENG 4793: Composite Materials and Processes20Effect of Glass Content on theMechanical Properties of GMRTShear Lint+Wt %glassTensilestrength, MPa(ksi)Tensilemodulus,GPa (msi)Flexuralstrength, MPa(ksi)Impactstrength, J(ft-lb)025.5(3.7)1.72(0.25)39.3(5.7)6.8(5.0)20 40.7(5.9)2.12(0.31)42.1(6.1)15.6(14.1)3055.2(8.0)2.76(0.40)44.2(6.4)18.3(13.5)40 84.1(12.2)5.9(0.86)53.1(7.7)21.7(16.0)ENG 4793: Composite Materials and Processes21“SANDWICH” OFTWINTEX*AROUND COREOF GMRT“SANDWICH” OFU.D. TAPEAROUND COREOF GMT (Kao)“SANDWICH” OFTWINTEX AROUNDCORE OF GMT(Osten)Glass Content, wt. % 50 4250Flexural Strength,MPa (ksi)170 (25) 210 (31)280 (41)Flexural Modulus,GPa (ksi)10.7 (1550) -11.4 (1640)Tensile Strength,MPa (ksi)210 (31) 250 (36)185 (27)Tensile Modulus,GPa (ksi)9.4 (1360) -9.0 (1300)* Vetrotex CertainteedENG 4793: Composite Materials and Processes22GMRT PANEL 40% E-glassVirginPolypropylene40% E-glass onSurface and20% in CoreVirgin PolypropylenePanel Density,grams/cc1.22 1.16Panel Thickness,mm3.8 4.3Flexural Strength,MPa (ksi)92 (13) 97 (14)Flexural Modulus,GPa (ksi)4.8 (700) 4.5 (650)ENG 4793: Composite Materials and Processes23Concluding Remarks• Towflex® finally successful- Limited by cost• Gcomp® success starting- Low cost sells well- Established GMT technology helps• GMRT science and technology needsexporationWhat mixtures? How dirty?What additives? Using natural fibersPredicting propertiesENG 4793: Composite Materials and Processes24Dynatup Impact Tester15.9 kg10 cm ×××× 10 cm sampleDynatup towerComputeracquisitionsystemSample holder5ENG 4793: Composite Materials and