INTERFACIAL ADHESION AND MECHANICAL PROPERTIES OF THERMOPLASTIC ACRYLIC POLYMER MATRIX CARBON FIBER REINFORCED COMPOSITES

Within several candidates of matrix polymers for carbon fiber reinforced thermoplastic composites (CFRTP), acrylic polymers have high potential in terms of low-temperature processing. We focused on the improvement in the interfacial adhesive properties between CFs and the acrylic polymers using several functional monomers for the co-polymerization with methyl methacrylate (MMA). Several functional acrylic monomers were co-polymerized with the MMA, and applied as the matrix polymers of the acrylic CFRTPs. It was observed that the copolymer matrices well-adhered to the surfaces of CFs, compared to the pure PMMA. The copolymer with acrylamide (AAm) indicated higher interfacial adhesive strength than that with hydroxyethyl acrylate (HEA). The hydroxyethyl acrylamide (HEAA) copolymer having both amide groups and hydroxyl groups showed very high adhesive strengths to CFs, which resulted in the high flexural strengths of the CFRTPs. The flexural strength of the pure PMMA CFRTP was 450 MPa. On the other hand, the co-polymerized acrylic matrices gave the increase in the flexural strength for the CFRTPs. Especially, the 3mol% HEAA copolymer achieved the two-fold flexural strength (900 MPa) on the acrylic CFRTP. The strength was equivalent level to the epoxy CFRP. The fatigue resistance of the HEAA copolymerized CFRTPs were also evaluated, in relation to the interfacial adhesive strength.