Influence of processing on ethylene-propylene block copolymers: Structure and mechanical behavior

Thin plaques (1, 2, and 3 mm) made of polypropylene homopolymer (iPP) and three ethylene propylene block copolymers (EPBC) with different ethylene content (5.5, 7.4, and 12% in weight) have been obtained by different processing methods (injection molding, injection and annealing, and compression molding). The morphology of the plaques has been studied using polarizing microscopy (PLM), differential scanning calorimetry (DSC), and wideangle X-ray scattering (WAXS). The results have been related with the mechanical properties of the plaques (MD and TD directions) in tension loading tests. We show the influence of the ethylene content, thickness, and processing method and conditions in the final morphology and how they affect the mechanical behavior. This knowledge can be used to tailor the final properties of a piece. (C) 2004 Wiley Periodicals, Inc.