Thermoplastic Matrix Composites from Towpregs

Abstract

In recent years, continuous fibre reinforced thermoplastic matrix composites have been successfully employed in the aircraft, military and aerospace industries due to the excellent properties (Brandt et al. 1993 & Nunes et al 2005a). In these and many other commercial engineering applications, they can replace other materials, such as thermosetting matrix composites. However, the high cost of the impregnation of continuous fibre thermoplastic composites, arising from the melting of the polymer or the use of solvents, still restricts their use in commercial applications. Hence, cost reduction largely depends on developing more efficient methods for impregnating fibres with high-viscosity thermoplastics and for processing final composite parts. This chapter summarizes the development of new technologies to fabricate long and continuous fibre reinforced composite structures from thermoplastic matrix semi-products (towpregs and PCT – pre-consolidated tapes) for commercial and highly demanding markets. The production of continuous fibre reinforced thermoplastic matrix towpregs and PCT’s was done using a recently developed coating line (Nunes et al. 2008, 2010 & Silva, R.F. et al. 2008). Using this prototype equipment, it was possible to produce glass fibre polypropylene (PP) and polyvinylchloride (PVC) towpregs for commercial markets and towpregs from carbon fibres and Primospire®, an amorphous highly aromatic material developed by Solvay Advanced Polymers, for application in advanced markets (Nunes et al. 2005, 2009 & Silva, J. F. et al. 2010). To process these thermoplastic pre-pregs into composite structures, conventional thermosetting equipments were adapted to fabricate thermoplastic matrix composites. Filament winding, pultrusion and hot compression moulding were the studied technologies. The mechanical properties determined on the final composites were compared with the theoretical predictions and have shown to be acceptable for the targeted markets. As applications, filament wound pressure vessels prototypes for gas and incompressible fluids were produced from towpregs and submitted to internal pressure burst tests [Silva, J. F. et al. 2008 & Velosa et al. 2009). These prototypes have accomplished all requirements of the applicable European standards.