IN-SITU HYBRID COMPOSITES CONTAINING REINFORCEMENTS AT 2 ORDERS OF MAGNITUDE

By combining the concepts of the in-situ composite and hybrid composit e, a concept of in-situ hybrid composites has been put forward. A comp osite structure of polyethersulfone reinforced by carbon fibres (CF) a nd thermotropic liquid crystalline polymer (TLCP) fibrils has been for med in injection-moulded bars by matching the characteristics and proc essing conditions of the TLCP and the matrix resin. These TLCP fibrils with large intrinsic aspect ratios are generated in-situ in the melt of the resin matrix during the processing of the ternary blends. This technique uses TLCPs to decrease the viscosity of the whole blend syst ems and to minimize the CF breakage as well. The improved processabili ty is especially beneficial for the processing of advanced engineering plastics. This technique, forming reinforcements at two orders of mag nitude in the resultant composites, utilizes these two reinforcements to balance the enhanced mechanical properties of the hybrid composites . (C) 1997 Elsevier Science Ltd.