Processing temperature window design via controlling matrix composition for polypropylene-based self-reinforced composites

Self-reinforced composites (SRCs) are easy to recycle because the matrix and reinforcement are composed of the same material. However, the narrow processing window makes it difficult to optimize the relationship between the internal structure and the mechanical properties. In this study, we adopted a strategy to control the melting temperature and flowability of the matrix to expand the processing window of a polypropylene (PP)-based SRC. To experiment with this strategy, 1500% drawn PP fiber was used as the reinforcement, while a PP/low-density polyethylene (LDPE) blend, PP/ethylene copolymer, or PP/ethylene/butene terpolymer were adopted as the matrix. The tensile strength of the PP-based SRC prepared by applying the copolymer matrix under optimized processing conditions was improved by 22.3%, as compared to that of the SRC prepared using the raw PP matrix. As a result, the design rule used to obtain optimum processing conditions for SRC production with outstanding mechanical properties was proposed.