Relationship between morphology and mechanical properties of polypropylene/ethene-co-butene binary blends with various butene contents.

A metallocene-based isotactic polypropylene (m-iPP) was blended with various types of ethene-co-butene rubbers (EBR). Blend miscibility was examined by means of dynamic mechanical analysis (DMTA). In addition, morphology was studied on cyclohexane etched cryofractured samples. Stiffness and toughness properties were assessed and interpreted in function of the blend miscibility. Izod tests served for the dynamic fracture toughness characterization. The essential work of fracture (EWF) approach was used for the characterization of the static fracture toughness. It was found that the 1-butene content of the EBR strongly affects the blend miscibility. A disperse structure was found as prerequisite for outstanding overall toughness. When distiguishing between resistance to crack initiation and propagation, it was found that they are changing adversely to one another. [ABSTRACT FROM AUTHOR]