Effect of Ethylene-Propylene Rubber Concentration and Composition on the Properties of Unipol Polypropylene Impact Copolymer Cast Film

The effects of ethylenepropylene rubber content (Fc) and ethylene content of rubber (Ec) on the mechanical properties of UNIPOL® polypropylene (PP) impact copolymer cast film have been studied. Thermal analysis has been found to be useful in explaining the structureproperty relationship of the film. In general, with increasing Fc: (a) tensile modulus and stress at break decreased and (b) tear and impact strengths increased. At higher Ec: (a) modulus, break tensile strength and puncture resistance increased and (b) tear and impact strengths decreased. With increasing Ec the polyethylenelike crystalline phase became more prominent in the rubber phase, and melting and crystallization temperatures and crystallinity of this phase increased. There was comparatively less effect on these thermal properties when Fc was increased at constant Ec.