Interfacial properties of PP/PP composites

Abstract

The interface structure of polypropylene (PP/PP) composites, consisting of homo-PP fibers and propylene-ethylene random copolymer matrix, was investigated. Generally, in the case of increasing the relative nucleus concentration on the fiber surface, transcrystalline structure grows at the interface instead of spherulitic growth. In this study, PP fibers with nucleating agent were prepared in order to increase the relative nucleus concentration. As a result, it was found that the amount of fiber surface nucleation in PP/PP composites gradually increases with the increase of nucleating agent, and transcrystalline structure grows on the PP fiber. Mechanical properties of PP/PP composites, consisting of homo-PP fibers and propylene-ethylene random copolymer matrix, were measured. While the modulus of PP fiber decreases with increasing amounts of nucleating agent, the modulus of the PP/PP composites remained relatively stable. The effects of the transcrystalline region on the macroscopic mechanical properties were discussed using the law of mixtures. It was shown that the presence of the transcrystalline structure at the interface enhances the mechanical properties of the PP/PP composites.