The effect of crystallinity on the mechanical properties of plain woven carbon fiber reinforced polypropylene

Abstract

In this study, the effect of crystallinity on the mechanical properties of carbon fiber reinforced thermoplastics (CFRTP) was investigated. Plain woven carbon fiber was used as reinforcement. Polypropylene (PP) and maleic anhydride modified polypropylene (MAPP) were used as matrix materials. The crystallinity of PP was controlled by heat treatment after hot press molding of CFRTP. The range of crystallinity of PP and MAPP were from 26% to 40%. Flexural and izod impact tests were conducted on CFRTP based on Japanese Industrial Standard (JIS) K 7074 and K 7110, respectively. Also, double-notched tests were conducted on CFRTP specimens. The crystal morphologies of single carbon fiber added thermoplastics were observed using a polarization microscope. As a result, the flexural strength and izod impact values of CFRTP using PP increased with an increase of crystallinity. The flexural strength and izod impact values of CFRTP using MAPP barely changed with an increase of crystallinity. However, the interfacial shear strength of CFRTP using MAPP increased with an increase of crystallinity. Crystallizations of PP and MAPP occurred around the carbon fiber after heat treatment. As a result, interfacial adhesion between fiber and resin increased with an increase of crystallinity.