Rome 15 – 17 April 2009

1. Second International Conference on Innovative Natural Fibre Compositesfor Industrial Application Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates Rome 15 – 17 April 2009 Scarponi Claudio * Pizzinelli Corrado Sebastiano * Sonia Sánchez-Sáez ** Enrique Barbero ** * Sapienza Università di Roma ** Universidad Carlos III de Madrid

2. Introduction: Natural Fibers Disadvantages: • Properties depend from many factors • Defects and irregularities • Water absorption (swelling and problems…) • Fiber/matrix adhesion… Vantages: • Good specific mechanical properties • Low cost, low weight, low tool wear • “Bio-friendly”, non toxic… • Thermal and electrical insulation Natural fibres might be a realistic alternative to glass fibres reinforced composites Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

3. Applications and possible market • Radome • Interiors (seats, caps, tables…) • Baggage container • Non primary structural applications in general Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

4. Aims of this work • Investigate the behavior of composites laminates reinforced by hemp fabric, processed by RTM • Improve the RTM process • determine the effect of damages caused by low velocity impact loads • Compare the results with literature Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

5. Reinforcement “plain weave” hemp fabric (National Canapificio Linificio-Spa of Verona) From previous studies alkalinizationwithsodiumhydroxideNaOH 1% wtdidnot produce convenient performance increase Fabric has not been chemically treated

6. Matrix It has been chosen an epoxy resin, because of its excellent mechanical properties and in particular for the resistance to interlaminar shear Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates (*calculated data)

7. RTM & PROCESS The panels fabrication has been performed at the Centro Sviluppo Materiali laboratories, with a Plastech T.T. machine. • command console • omogenizator (the degassing is performed here only for the first panel) • mold COMMAND CONSOLE OMOGENIZATOR MOLD Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

8. Mold & Countermold • 400x400 mm • Electrically heated • The resin, after being aspired from the omogenizator, is degassed • On the mold there are some little holes through which is aspired the resin in excess Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

9. Injection & polymerization • 0°/90° fabric disposition • Vacuum • Degassing & Resin injection at 0.5 bar • After having wetted half tissue, pressure is increased and kept to 3 bar • Polymerization sequence • 6h at room temperature, to reduce risk of reactions • 24h at 40 º C Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

10. Hemp-Glass comparison zoom 2 hemp threads zoom Glassfiber fabric Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

11. Panel 1 • bad wetting • non uniform resin distribution • voids Resin Inlet PANEL 1. (12 plies) Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

12. Resin Trap and Improved degassing Also the maximum pressure has been decreased The “resin trap” prevents the excess resin flow to go back into the pump Degassing; it is visible the typical “foam” Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

13. Panel 2 & comparison PANEL 1. (12 plies) PANEL 2. (14 plies) Resin Inlet Resin Inlet Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

14. Properties and comparison Resin Inlet point Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

15. Tensile and flexural tests (4PBT) Tensile: 5 specimens tested on a Zwick machine at room temperature, with a load cell of 250 kN, following normative ASTM D3039 (D638 for test on resin) 4PBT: 6 specimens tested at room temperature, with a load cell of 200kN, following normative ASTM D790-86. Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

16. Tensile test Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

17. Flexural test Since the trend is not linear and the slope of the curve decreases, rupture is probably due to shear stresses. Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

18. Impact test Square specimens 100x 100 mm have been utilized for the impact test (3 for each energy level) bounded with a clamping (ASTM D5628-96, ASTM D5428-98th). The hemispherical head impacter has a mass of 3.966 Kg and a diameter of 12.7 mm Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

19. Impact • Force-time curves. With the help of the table is possible to distinguish: • Incipient damage time • Displacement at this time

20. Impact 2 • Force-deflection average curves. With the help of the table is possible to distinguish: • Max displacement • Instant of max displacement

21. Energies involved Eabsorbed, is the asymptotic Energy value and represents the energy dissipated in fracture mechanism. It can be divided in two major type of contributions: energy expended to generate the damage (Edamage) and energy absorbed by the system by various means such as vibrations, heat, anelastic behaviors, etc. (Edisp):

22. Impact 3 Energy-time curve red Eimpact, Green E absorbed black E elastic Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

23. Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

24. Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

25. HYSTERESIS (Santulli- STUDY OF IMPACT HYSTERESIS CURVES ON E-GLASS REINFORCED POLYPROPYLENE LAMINATES) Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates

27. Comparison with jute/vynilester hybrids: same geometries, impact energy and boundary conditions

28. Comparison with jute/vynilester hybrids: Same MASS, geometries, impact energy and boundary conditions

29. Impact side 5J 10J Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates 15J

30. Back side 5J 10J Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates 15J

31. BACKLIGHT: 10J impacted specimens (10 x 10 cm) BACKLIGHT: 5J impacted specimens (10 x 10 cm) Original Original Digitally sharpened and “inverted” Digitally sharpened and “inverted”

32. BACKLIGHT: 15J impacted specimens (10 x 10 cm) Original Digitally sharpened and “inverted”

34. Conclusions and possible future developments • An RTM system, has been successfully used with hemp fibers. • It has been proven experimentally that process parameters greatly influence the final product • The process has been improved with a negligible cost impact. Even if it was not the aim of this paper, further enhancements are possible in order to achieve more improvements such as geometry and number of resin immission holes, pressure-time curves, curing process. • Hemp/epoxy composites exhibit good impact properties • It is confirmed the hypothesis that it can be possible to start using for secondary structures hemp as a reinforcement alternative to glass. Further studies are needed also to characterize the internal behavior of the material and residual properties.

35. Acknowledments • Ing. Fulvio Ferraro of the CSM for the RTM process; (CSM: Centro Sviluppo Materiali s.p.a., via di Castel Romano n. 100, cap 00128 Roma.) • Ing Teresa Vetere for the resistance tests • Prof. Carlo Santulli

36. Thank you for your attention! Impact load behaviour of RTM (Resin Transfer Moulding) hemp fibre composite laminates Scarponi Claudio Pizzinelli Corrado Sebastiano * Sonia Sánchez-Sáez Enrique Barbero *Reference author; E-mail: sebarm86@hotmail.com Dipartimento di Ingegneria Aerospaziale e Astronautica “Sapienza Università di Roma”