Thermotropic liquid crystal polymer fabric reinforced polyimide composite materials

Abstract

An aromatic copolyester thermotropic liquid crystal polymer (LCP) fabric was used to reinforce a polyimide (PI) matrix to produce composites. The LCP/PI composite was made to eliminate directional difference in the mechanical properties of LCP by controlling the individual reinforcement fabric alignment in different directions without losing any mechanical properties. As a result, a transversely isotropic LCP composite material could be obtained from the highly anisotropic LCP fiber. Interfacial adhesion between the LCP and polyimide was greatly improved by a NH3/H-2 plasma treatment on the LCP fabric, thereby the significantly improving mechanical properties of the composite. Moreover, inter-laminar shear strength of the LCP/PI composite was further increased after heat treatment at 220 degreesC for 1 hour. The LCP/polyimide composite retains stable mechanical properties up to 250 degreesC.