Influence of Water Absorption and Temperature on the Mechanical Properties of Discontinuous Carbon Fiber Reinforced Polyamide 6

Abstract

Carbon fiber reinforced thermoplastics (CFRTP) show relatively high mechanical properties and are expected to be feasible materials for mass production of light-weight structures. In particular, discontinuous CFRTP (DCFRTP) with affordable resins have been developed to realize excellent formability and mechanical properties. Currently, polyamide 6 (PA6) is a promising matrix for CFRTP in mass-produced automobiles. However, due to the hygroscopic and viscoelastic properties of polyamide resins, the influence of water absorption on the mechanical properties of CFRTP under varying temperature is necessary to be investigated. In this study, the influence of water absorption on the mechanical properties of discontinuous CF/PA6 composites was investigated. Chopped carbon fiber tape reinforced thermoplastics (CTT), which are randomly oriented strand (ROS) composites, were selected as DCFRTP. The mechanical properties of the composites were investigated by a three point bending test between −40 and 125 °C, as a function of water absorption. The flexural modulus were calculated using the Timoshenko beam equation to predict degradation by water absorption. The mechanical properties of CTT have a relatively high sensitivity to water absorption.