New Long Rayon Fiber Reinforced Thermoplastics Utilizing the LFT-D Process ACCE, 12.-14. September 2005, Troy, USA Dr. Frank Henning Oliver Geiger
Motivation for a LFT direct process Additives Economical advantage Flexible material composition + LFT direct process Polymer resin Semi-finished product manufacturing Semi-finished product manufacturer Semi-finished product processing GMT or LFT-G Molder LFT composite part Glass fibers LFT direct process In-House Recycling Folie 2
Longfiber Reinforced Thermoplastics New Material Development Requirements: Mechanical properties Material homogeneity Reproducibility Material data for part design Reduction of local material anisotropy Definition long fibers: Injection molding: >1 bis 5 mm Compression molding: 10 bis 40 mm Strength / Stiffness Short fiber reinforced plastics Particle filled plastics Toughness Long fiber reinforced plastics Non reinforced plastics Rubber Folie 3
LFT-D-ILC Base Equipment Fully automized material handling Hydraulic Press AVK-TV Innovationspreis 2001 Conveyor belt for LFT strand Provision of rovings In-line compounder LFT die Mixing extruder 2002-09-12 - Page 4
Material development tailored to the application Fiber orientation Fiber content Fiber properties Fiber diameter Fiber-matrix adhesion Material properties Fiber length Fiber-matrix dispersion Properties of polymer Void content Folie 5
Material Development Flexibility Adjustment of material properties based on requirements Possibility of selection of polymer and fiber type Material combination just looks complex well managable Individual intensity of backward integration possible (masterbatch) Company specific Know-How Optimized for customer or applications Superset line control ensures safe and reproducible production Folie 6
Flexibility for company specific solutions Polymers: - Polypropylen - Nylon: PA 6, PA 6.6 etc. - Polyethylenterephtalat (PET) - Styrenic Copolymers: ABS, ASA, SAN etc. - Blends IL-Compounder Reinforcements: - Glass fibers - Natural fibers - Carbon fibers -Syntheticfibers - cellulotic fibers Compression molding Mixing extruder (Twin screw compounder) Presse LFT strand Folie 7
Advanced LFT based on Engineering Thermoplastics Tensile strength [MPa] 140 120 100 80 60 40 20 Flexibility in selection of matrix resins 112 78 60 126 0 PP/GF30 ABS/GF30 PA/GF30 PET/GF30 Long fiber reinforced Engineering Plastics offer new applications for LFT s Folie 8
Distribution of Fiber Length Influence on Material Properties Stiffness: Fiber length 0,1 to 1mm Fillers and short fibers Strength: Fiber length 1 to 10mm Short fibers Impact: Fiber length > 10mm Long fibers Norm. Properties [ - ] 1.0 0.8 0.6 0.4 0.2 0 0.1 95 % level Stiffness Impact Strength 1 10 Fiber length l [mm] 100 Source: Schemme, SKZ-Fachtagung Karosseriekonzepte mit Kunststoffen, Würzburg 2002 Based on Thomason & Vlug Folie 9
Tensile Properties of Nylon PA6.6/GF30 @ 23 C 20000 18000 16000 187 Mechanical properties DAM @ 23 C E-modulus Stress @ break Strain @ break 179 200 180 160 14000-20% 142 +20% 140 12000 120 10000 9800 8437 10081 100 8000 80 6000 4000 2000 0 CAMPUS Database Injection Molding 3 2.6 2.1 ZYTEL 70G30HSL BK39B, moulded ZYTEL 70G30HSL BK39B, machined Compression Molding (LFT-D) N66 LFT 30%, machined 60 40 20 0 Folie 10
Notched Charpy Properties of Nylon PA6.6 and GF50 @ 23 C LFT brings a clear benefit in notched impact Notched Charpy performance is trippled KJ/m² 90 80 70 60 Notched Charpy @23 C Injection molding LFT-D Compression molding 50 40 30 20 10 0 Injection Molding 30% by weight glass Compression Molding (LFT-D) 50% by weight glass Folie 11
Multi-axial Impact of Nylon PA6.6/GF30 and GF40 @ 23 C LFT brings a clear benefit in multi-axial impact 3500 Multiaxial Impact @ 23 C 16 3000 Max. Force (N) 14 2500 Energy (Fmax) (J) Energy (J) 12 Force (N) 2000 1500 2mm specimen thickness 10 8 6 Energy (J) 1000 500 Injection Molding Compression Molding (LFT-D) 4 2 0 0 70G30 reference Resin 1 Resin 2 PA6 LFT 30% PA6 LFT 40% Folie 12
Heat Deflection Temperature @ 1.81 MPA ISO 75-A 0 C 105-150 C 163 C 255 C 264 C PP LFT 30% 180-220 C Zytel 70G30 Zytel LFT 30% Zytel 70G50 258 C Zytel LFT 50% Engineering Polymers Zytel 75LG50HSL BK031 259 C Zytel HTN LFT 50% 200-250 C Folie 13
Creep Measurements @ 130 C, 4000 MPa The LFT in-flow tensile modulus is 20% higher compared to 70G35 After 1000 hours, the LFT in-flow tensile modulus is 50% higher LFT 50% brings another performance increase 70G35HSLX PA66 LFT 30% PA66 LFT 50% Folie 14
LFT-D Material Development Cellulose Fiber Reinforced PP Goal: Modification of LFT-D-ILC process technology developed for the in-line compounding of glass fibers for the direct incorporation of cellulose regenerated fibers Polymer Additives Fiber Rovings IL-Compounder Twin-Screw Mixing Unit Plastifikate Compression Molding Folie 15
Advantages of engineering regenerated cellulotic fibers Reduced density compared to glass fibers weight reduction: r CRF = 1,5 kg/dm³ versus r GF =2,5 kg/dm³ High elongation at break results in high impact resistance especially at low temperatures (T = -30 C) Low sensitivity regarding splintering - qualification of RAYON fiber reinforced composites for automotive interior applications Combination with biopolymers enable the in-line compounding of 100% renewable LFT Reproducible material properties and continuous rovings compared to natural grown fibers Folie 16
Cellulose Cellulose is the most commonly existing natural product with an annual growth rate of approx. 10 10 t Cellulose = Poly (β-(1,4)-anhydroglucose) Basic module: AGU = C 6 H 10 O 5 (chem.), Cellobiose (phys.) Chemical Structure: clarified by Haworth 1928 Physical structure semi-cristalline (Polymorphy) fibrillar morphology (streched polymer chain) physical structure still in discussion Major problem: structural diversity distinctive structural imperfection Problems of industrial processing Cellulose is not fusible Cellulose is not soluble in common solvants Cellulose first has to be isolated (chemical pulp manufacture from wood) Quelle: Fraunhofer IAP Folie 17
Properties of hemp yarns of different origin Material Source Yarn count Strenght Elongation Modulus Provider tex cn/tex % cn/tex Hanf 2.4/1 Rohemp 357.8 12.2 3.88 593 Hanf 5/1 Rohemp 205.3 12.9 3.80 518 Hanf 10/1 Rohemp 99.5 29.8 3.15 1148 Hanf 10/1 bleached Rohemp 75.8 17.7 1.95 1154 Hanf 10/1 Hattorf 93.6 17.3 2.77 767 Hanf 5/1 Polen 228.4 26.4 3.18 1349 Hanf 7.1/1 Polen 256.9 22.9 2.50 1434 Hanf 10/1 Polen 103.4 23.4 2.66 1253 Engineering Cellulose Stable Fiber Cordenka 244 51,7 12.5 Quelle: Fraunhofer IAP Folie 18
Cellulose Fibers Cellulose Fibers Natural Fibers Engineering Stable Fibers Seed Fibers Wood Fibers Viscose Carbamat Cotton wool Kapok Bast Fibers Hardwood Softwood Lyocell Flax Hemp Jute Ramie Leaf Fibers Agave (Sisal and others) Banana (Manila-Hemp and others) Lilienfaser (New Zealand-Hemp) Coco Fibers (Fruit Fibers) Grass Fibers Cupro Enginnering Stable Fibers = cellulosic synthetic fibers = man-made cellulosics = cellulose-stable fibers Quelle: Fraunhofer IAP Folie 19
CRF in Composites - Processing Manufacturing Manufacturing of of semi-finished semi-finished products products Injection Injection Molding, Molding, Extrusion Extrusion of of PP/CRF-Granulates PP/CRF-Granulates Injection Injection Compression Compression Electronics Electronics Housings Housings Automotive Automotive Interior Interior Incorporation Incorporation of of continuous continuous fibers fibers In In thermoplastic thermoplastic melt melt Incorporation Incorporation of of chopped chopped CRF-Fibers CRF-Fibers Injection Injection Compression Compression Automotive Automotive Interior Interior Automotive Automotive Interior Interior Folie 20
Processing of Granulates by Compression Molding Melting of granulates in single-screw extruder Einschneckenextruder Granulate PPRayCo25 Basic Plastifikate Presse Compression Molding Beam Structure Folie 21
Material Properties of Injection Molded Parts (Short Fiber Reinforced) Polypropylene with 25 percent by weight RAYON short fiber reinforcement Properties Procedure Unit Norm measured value Matrix resin PP Fiber content wt.% 25 Tensile modulus 2mm/min GPa ISO527 2,7 Tensile strength 50mm/min MPa ISO527 72 Strain at break (tensile) 50mm/min % ISO527 12 Flexural modulus 2mm/min GPa ISO178 2,1 Flexural strength 2mm/min MPa ISO178 60 Flexural tension at 3,5% 2mm/min MPa ISO178 52 Charpy Impact (un-notched) 23 C, 4J kj/m 2 ISO179 85-18 C, 4J kj/m 2 ISO180 83 Charpy Impact (notched) 23 C, 4J kj/m 2 ISO179 11-18 C, 4J kj/m 2 ISO180 7 Hardness Shore D 23 C DIN53505 70 Heat deflection HDT-A 1,8 MPa C ISO75 80 Density calculated g/cm 3 0,998 Source: http://www2.iap.fhg.de/verbundwerkstoffe/de/index.html Folie 22
Direct Processing of CRF Composites - Challenges Chopping of CRF high elongation Homogenisation of chopped fibers in matrix polymer by mixing unit Cutting of CRF-LFT plastificates into strands for compression molding Compatibility of fibers and polymer fiber-matrix adhesion Optimization of flow capability of CRF reinforced polymer Folie 23
Direct Processing of CRF Composites Process Modifications CRF-Rovings Cutting Roller Pressing Roller Compounding-Extruder Polymer Chopped CRF Fibers Polymer- Melt Film Feeding Chute Infeed Zone Mixing Unit Folie 24
Direct Processing of CRF Composites Material Homogeneity Significant improvement of material homogeneity by process optimization LFT-D Technology not optimized (25 weight-% fiber content) Optimized LFT-D Technology (25 Gew.-% fiber content) Folie 25
Material Properties of Extrusion Compression Molded Parts Polypropylene with 20 percent by weight RAYON long fiber reinforcement (fiber length 12 mm) compared to long glass fiber reinforced PP [MPa] Stiffness Zug-E-Modul E-Modulus 5000 4000 LFT-D PP/GF30 3000 LFT-D PP/CRF20 [MPa] Tensile Zugfestigkeit Strength 2000 1000 0 Faserorientierung Fiber orientation0 0 Fiber Faserorientierung orientation 90 90 80 70 60 50 40 30 20 10 0 LFT-D PP/GF30 LFT-D PP/CRF20 Faserorientierung Fiber orientation0 0 Fiber Faserorientierung orientation 90 Folie 26
Material Properties of Extrusion Compression Molded Parts Polypropylene with 20 percent by weight RAYON long fiber reinforcement (fiber length 12 mm) compared to long glass fiber reinforced PP [J] Durchstoßenergie Falling dart test 18 16 14 12 10 8 6 4 2 0 LFT-D PP/GF30 LFT-D PP/CRF20 [kj/m²] 80 70 60 50 40 30 20 10 0 Charpy Impact un-notched LFT-D PP/GF30 LFT-D PP/CRF20 Fiber orientation 0 Fiber orientation 90 Folie 27
Current Material and Process Developments Development of a process unit for large scale production equipment in cooperation with Dieffenbacher Suitable cutting technology for this type of synthetic fibers Automated handling of LFT-Strands Optimization of material composition Mixing of Glass and CRF for improvement of HDT Value Stabilization/Additives for flame resistance with respect to railway transportation Use of biopolymers Composites made from 100% renewable Ressources Polylactid (Polylactic acid PLA) in combination with CRF Folie 28
CRF in Biopolymers Tensile Strength 140 120 124 Zugfestigkeit [MPa] 100 80 60 40 70 61 78 20 0 PP/GF30 PLA/GF30 PP/CRF25 PLA/CRF25 Folie 29
CRF in Biopolymers Tensile Strength 12000 10000 10200 Zugmodul [MPa] 8000 6000 4000 6500 2900 5200 2000 0 PP/GF30 PLA/GF30 PP/CRF25 PLA/CRF25 Folie 30
LFT-D Regenerated Cellulotic Fiber Reinforced Polypropylene VOLVO Underbody Cover Made of PP/CRF25, 25 weight-% Fibers Unterbody Cover OPEL Corsa made of PP/CRF20, 20 weight-% Fibers Folie 31
Flame Retarding Behaviour of CRF Composites Characterisation of combustion behaviour of different composites 25 weight-% CRF reinforced Polypropylen (IAP granules, short fibers), injection molded Length of burning time for 100mm 229 s 25 weight-% CRF reinforced Polypropylen (ICT, LFT-D), compression molded Length of burning time for 100mm 327 s 30% glass fiber reinforced Polypropylen (ICT, LFT-D), compression molded Length of burning time for 100mm 233 s Folie 32
Summary Extended and modified LFT-D-ILC technology employing chopped fiber dosing technology leads to an economic manufacturing of CRF reinforced parts Compression molding is an attractive process technology especially when manufacturing large parts and a high number of units High mechanical properties enable the use of the compound for automotive applications Long fibers provide high impact strength and avoid slivering of the part during damage Regarding material homogeneity the process technology was optimized Successful manufacturing of demonstrator parts Folie 33
http://www.neue-verbundwerkstoffe.de http://www.ict.fraunhofer.de Folie 34