Reactive Thermoplastic Composites - A Potential Game Changer?

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1 Reactive Thermoplastic Composites - A Potential Game Changer? Dr. Conchúr Ó Brádaigh Senior Lecturer, Mechanical Engineering National University of Ireland, Galway R & D Director, ÉireComposites Teo., Co. Galway, Ireland

2 Acknowledgements Dr. Harald Bersee, Suzlon Energy & TU Delft Dr. Klaus Gleich, Johns Manville Dr. Véronique Michaud, EPFL Lausanne Mr. Gerhard Entholzer, Engel

3 Reactive Thermoplastic Composites - A Potential Game Changer? Introduction Thermoplastic Composites Reactive Thermoplastic Systems Cyclic CBT Anionically Polymerised PA-12 PA-6 Systems Future Outlook/Developments

4 ÉireComposites Activities 60 staff in total including 20 engineers in Galway, Ireland. Aerospace and renewable energy composites Design, testing and manufacturing International customer base Bombardier, Airbus, Aircelle, Cytec, Lotus, GKN, Siemens Advanced R&D in thermoplastic composites and large heated tooling PRI Nadcap (Composites, Testing and NDT) EN/AS 9100, ISO & ISO 17025

5 Composites Testing Facilities 400kN static test machine 250kN static test machine 10kN static test machine 5 x 100kN fatigue test machines 2 x 250kN fatigue test machines Fully-equipped workshop for specimen preparation DMTA and fibre volume fraction facilities Microscopy and void analysis All static test machines with the exception of the 1MN machine are fitted with environmental chambers & can operate between -75 o C to +200 o C

6 Irish Centre for Composites Research (ICOMP) (Hosted by the University of Limerick) Centre based at the University of Limerick, with projects based at other institutions (North and South) Irish Government support of 6.0m over 5 years ( ) Industry commitment of 1.0m over 5 years ( ) Industry-dominated Centre Board Research Agenda defined by Industrial consortium: ÉireComposites, Bombardier Aerospace, Tyco Electronics, Henkel Ireland, Element 6, EJ Access Solutions, B/E Aerospace, Burgmann Packing, Global Green Composites, Turas Cycles, Dortek, Ohshima Ireland

7 Marine Renewable Energy Ireland 25.0 million SFI-Funded Research Centre ( ) Tidal Energy Map Wave Energy Map

8 Reactive Thermoplastic Composites - A Potential Game Changer? Introduction Thermoplastic Composites Reactive Thermoplastic Systems Cyclic CBT Anionically Polymerised PA-12 PA-6 Systems Future Outlook/Developments

9 Advantages of Thermoplastic Composites (TPCs) Wide range of polymers available mechanical and physical properties vary from acceptable to superior Rapid processing (TPCs only need to be melted and consolidated) Environmentally friendly / zero volatiles during processing High toughness / impact resistance Good to high corrosion / solvent resistance Outstanding flame/smoke/ toxicity (FST) Can be thermally welded or adhesively bonded Can be recycled by re-melting at end of life

10 Desirable thermoplastic polymers have high molecular weights and therefore high melt viscosities SAMPE Masterclass, NCC, Bristol, October 2 nd Dr. C. Ó Brádaigh Disadvantages of TPCs Similarly, melt temperatures are high compared to thermoset cure temperatures Combination means high processing pressures and temperatures TPC business case usually needs high part volumes to justify heavy tooling & capital expenditure

11 Application of TPCs to Aerospace Primary Structures Partner in EU Framework 6 ALCAS Research Program ( ) Design and Build of CF/PEKK Lateral Wing Rib with Airbus UK Manufacture of CF/PEKK Centre Wing Box Stiffeners w. Airbus France

12 Composite Wind Turbine Blades & Marine Structures Thermoplastic micro-wind turbine blades Blades up to 20KW in glass fibre PP Catamaran hulls in GF/PP GF/PP catamaran rudder with in-situ foamed TP core

13 Reactive Thermoplastic Composites - A Potential Game Changer? Introduction Thermoplastic Composites Reactive Thermoplastic Systems Cyclic CBT Anionically Polymerised PA-12 PA-6 Systems Future Outlook/Developments

14 Source: Dr. Harald Bersee, Suzlon Energy Blades, ITHEC 2012 Conference

15 Reactive Processing of Thermoplastic Composites Reactive processing: Processing: From the monomer directly to the polymer by in-situ polymerization Vacuum Infusion possible Large, thick, integrated parts Commonly used technology (RIM of PU) Below melting temperature of polymer Short curing cycle (minutes) Thermoplastic RTM

16 Reaction-Moulding of TPCs Example: Cyclic PBT System Purpose: Reduce viscosity of thermoplastic polymer by using liquid monomer, which infiltrates the fibres and then polymerises in-situ (and then crystallises) Linear Polymer Produce Cyclics Cyclic Oligomers Make Products c isothermal processing with no exotherm Polymer can be de-polymerised for recycling

17 CBT Monomer Polymerisation Rheology Complex Viscosity Curve Cyclics XB3-1 Polymerized at 170C, 190C and 225C n* [Pa s] Pa.sec needed for vacuum infiltration at >50% Vf 170C 190C 225C t [s]

18 Liquid-Moulding of TPCs Vacuum Assisted RTM of Cyclic PBT/Glass Fibre System 40mm thick laminate Glass/CBT Glass/Epoxy E GPa E GPa E GPa E GPa G GPa G GPa kg/m kg/m 3 VARTM Cell Coll, S.M., Murtagh, A.M. and Ó Brádaigh, C.M., Proceedings of the SAMPE Europe Conference, Paris, France, April 2004.

19 Liquid-Moulding of TPCs Resin Film Infusion of Cyclic PBT/Glass Fibre System Resin Film Infusion 1-Part CBT System Vacuum bag Pre-preg stack Vacuum V 1.0m wide Wind Blade Section Heated mould Doyle, A. et al. Composite articles and composite materials and processes for their construction, European Patent Application No , 2006

20 Liquid-Moulding of 13.0m TPC Wind Blade Cyclic PBT/Glass Fibre System Heated Tool with Cost-Effective Ceramics CBT Blade Tooling is made from glass & carbon-fibre & thermoplastic reinforced ceramic Electrically-heated, temperature capability up to 500 C Low power-input required, ceramic a good insulator Temperature profile can be closely controlled 600 Kg Glass/PBT Blade In-Situ Polymerisation - Processed at 200 C Largest TPC structure at the time A Heated Mould for Moulding Polymeric Composites, A Method for Making Such Mould and its Use, European Patent No. EP B, September 2012

21 CBT System Difficulties encountered in scale-up to commercial plant Single-source of material Commercial problems Availability??

22 RTM Equipment : Thermoplastic Assembled by Dosiplast (Balzers, FL) Anionically Polymerised Lactam-12 APLC-12 J. Verrey 22 LC T Injection is performed at constant flow rate LABORATOIRE DE TECHNOLOGIE DES COMPOSITES ET POLYMERES

23 PART COST Component: Monolithic floor-pan for a A00 car series (VW Lupo) Simplification of real design W=14.6kg V f =54% Define correct strategy (nb of tools, ) according to the production volume and to the selected materials.

24 PROCESS WINDOW DETERMINATION CONCLUSION Injection conditions: Tmould = 170 C Tmonomer = 170 C Flow rate = 100 cc/min, injection time about 8 minutes, polymerisation 20 minutes

25 CONCLUSION PROCESSED PARTS

26 PART COST Cost Segmentation 24% increase (utilisationbased), mainly due to: Temperature cycling of the mould Low reactivity Longer cycle time

27 Reactive PA-12 System Modulus of PA-12 not high enough for composite mechanical properties Expensive polymer/monomer system Polymerisation chemistry difficult, e.g. reaction is moisture-sensitive Thermal cycling of mould and low reactivity causes increased costs No sizing packages available for fibres

28 TU-Delft Thermoplastic Composite Demonstrator Anionically-Polymerised PA-6

29 TU-Delft Thermoplastic Composite Demonstrator

30 TU-Delft Thermoplastic Composite Demonstrator

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37 Reactive PA-6 Systems Widely-available polymer, used in many automotive applications Reasonable cost polymer Better mechanical properties than PA-12 Hybrid/over-moulding very attractive Moisture-sensitivity in polymerisation reaction PA-6 moisture uptake (as high as 5%) Need for faster polymerisation reactions Need for tailored fibre sizings

38 Reactive Thermoplastic Composites - A Potential Game Changer? Introduction Thermoplastic Composites Reactive Thermoplastic Systems Cyclic CBT Anionically Polymerised PA-12 PA-6 Systems Future Outlook/Developments

39 Johns Manville Fiber Technology Johns Manville Reactive Glass technology: Glass fiber with surface-bonded activator group for the polymerization of caprolactam Polyamide-6 grows from glass surface: Grafting from approach Strong covalent bonding at fiber-matrix interface for efficient load transfer from resin matrix to reinforcing fibers Improved mechanical properties, including flexural, tensile, and shear strengths Improved aging performance * * * * * * Grafting-from In-situ polymerization of caprolactam Glass fiber bonded with activator groups Glass fiber grafted with polyamide-6 Johns Manville 2013

40 Reactive Glass Benefits Reactive Glass Non-Reactive Glass Strong fiber-resin bonding; Failure in resin matrix Weak fiber-resin bonding; Failure at matrix/fiber interface Johns Manville 2013

41 Reactive Glass Benefits Glass integrated with the polymer matrix through strong covalent bonding Significant improvements in composite properties flexural strength, ILSS Interfacial bonding strength tunable Mechanical Property Improvement: Reactive Glass vs. Non-reactive glass Reactive Glass: Strong fiber-resin bonding Johns Manville 2013

42 Game-Changer in Automotive???? ? BMW i3 Electric Vehicle High pressure RTM carbon/epoxy parts ,000 units per annum?? Injection moulded TP skins for toughness Difficult recycling of thermoset composites Expensive / needs Govt subsidies High-Volume Composite Vehicle 1,000,000 per annum Rapid (<100 seconds) manuf. Cost-competitive with metals Recyclable/repairable TPC reaction moulding / pressforming / welding / disassembly

43 Summary Reactive thermoplastics have many advantages such as low viscosity, potential for fast polymerisation and good mechanical properties for moulding of complexshape composite components Currently available systems are not sufficiently technically or commercially developed to be viable for many industries Significant developments are taking place in robust polymer and fibre chemistry and in fibre sizing solutions Potential game-changer for high-volume production of composite components