Phase behavior and mechanical properties of heterophasic polypropylene-ethylene/propylene
copolymers systems (in English)
Polimery 2005, No 4, 279
In the following study the interactions between the phases, the morphology development and the resulting mechanical performance of the heterophasic polypropylene-ethylene/propylene copolymers (PP/EP) systems were investigated with respect to EP composition and matrix and dispersed phase molecular weights. It was shown that the compatibility between the components forming the matrix and the dispersed phase, as well as the dimensions of the dispersed domains were primarily controlled by ethylene content in EP. The decrease of ethylene content in ethylene/propylene copolymer was found to produce a strong refinement of the dispersed particle size and accordingly a reduction of the brittle to ductile transition temperature (TBDT) of the materials, as defined by conventional impact testing. However, the general fracture energy level was found to be governed by the molecular weights of the blend components. Increasing molecular weight of EP as well as of PP showed a beneficial effect on the toughness of the investigated blends.
Key words: polypropylene, ethylene/propylene copolymers, blends, heterophasic systems, dynamic mechanical analysis, morphology, impact strength
Phase behavior and mechanical properties of heterophasic polypropylene-ethylene/propylene copolymers systems (in English)