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 variou s types of ethene-co-butene rubbers (EBR). Blend miscibility was examined b y means of dynamic mechanical analysis (DMTA). In addition, morphology was studied on cyclohexane etched cryofractured samples. Stiffness and toughnes s properties were assessed and interpreted in function of the blend miscibi lity. Izod tests served for the dynamic fracture toughness characterization . The essential work of fracture (EWF) approach was used for the characteri zation of the static fracture toughness. It was found that the 1-butene con tent of the EBR strongly affects the blend miscibility. A disperse structur e was found as prerequisite for outstanding overall toughness. When distigu ishing between resistance to crack initiation and propagation, it was found that they are changing adversely to one another. (C) 2000 Kluwer Academic Publishers.