Ultra-high impact PPR composites at low-temperature through enhanced preferential loading of nanoparticles at polymeric interface induced by properly vulcanized rubber dispersed phase

A variety of low-temperature toughened, rigid-tough balanced polypropylene random copolymer/ethylene propylene rubber/silica (PPR/EPM/SiO2) nanocomposites were prepared by properly crosslinked rubber phase. The impact test results showed that the slightly vulcanized PPR/EPM/SiO2 composites presented lower ductile-to-brittle transition temperature (Tbd) and more excellent low-temperature toughness than unvulcanized or highly vulcanized composites, and there was hardly rigidity loss induced by slight vulcanization. SiO2 distribution, the size of EPM dispersed phase and EPM relaxation were investigated by TEM, SEM, rheology and DMA, respectively. It was found that the remarkable decrease of Tbd for slightly vulcanized PPR/EPM/SiO2 composites was due to the synergistic effect of SiO2 nanoparticles and vulcanization of rubber phase. Furthermore, the origin of excellent low-temperature toughness for vulcanized PPR/EPM/SiO2 composites was ascribed to the enhanced interfacial distribution of SiO2 nanoparticles induced by moderate vulcanization of rubber phase, which increased damping loss of rubber phase, increased interfacial area and decreased the matrix ligament thickness.