The properties of polymer blends of the β‐modification of polypropylene and an elastomer

Abstract

AbstractBlends of β‐polypropylene with elastomers have been prepared under laboratory and processing technological conditions. As a result of the elastomer addition the temperature interval favourable for the formation of the β‐modification became narrower. Blends have spherulitic structure like pure β‐PP. The elastomer has negligible effects on the size of spherulites and on the rate of crystallization. Optical microscopy and DMA measurements revealed that the blends were two‐phase systems in the solid state.The mechanical properties of the blends are close to those of β‐PP in the investigated composition range. Increasing elastomer content reduced the strength characteristics but considerably improved cold impact resistance, the most beneficial combination containing about 8–12% of elastomer. A mathematical relationship has been proposed describing the relationship between impact strength and elastomer content. The dependence of the structural characteristics and macroscopic properties of elastomer‐modified β‐PP blends on the composition and on the temperature is similar to that of the identical β‐PP blends.