Abstract: This paper reported a study of effects of ethylene-octene copolymer (POE), talc, and high-density polyethylene (PEHD) contents on mechanical properties, crystallization behavior, thermal decomposition behavior, and morphology of polypropylene (PP) composites. Impact toughness of the composites tended to increase with a decrease in the PP/POE viscosity ratio. The optimum mechanical properties were gained for the composites with PP/POE/talc/PE-HD weight ratio of 13/4/12/3. Compared with pure PP, the composites achieved an increase in flexural modulus by 60.1 % and in impact strength by 435.9 %, whereas their tensile strength and flexural strength were reduced by 27.4 % and 17.4 %, respectively. The interface interaction between PP and POE phases was enhanced due to the presence of PE-HD, thus improving the impact toughness of the composites. The introduction of talc or PE-HD into the composites also resulted in an improvement in initial decomposition temperature and the temperature at the maximum weightloss rate and, therefore, enhanced the thermal stability of the composites.

Key words: polypropylene, ethylene-octene copolymer, high-density polyethylene, high modulus, impact strength