Structure and Mechanical Properties of a Talc-Filled Polypropylene/Ethylene-Propylene-Diene Composite After Reprocessing in the Melt State

A commercial talc-filled polypropylene/ethylene-propylene-diene terpolymer composite was repeatedly injection molded up to five cycles to study the effects of reprocessing on the structure, morphology, and mechanical properties. Reprocessing did not change either the chemical structure or the thermal behavior of the composite, but led to a slight molecular weight reduction, due to shear-stress-induced chain scission. Talc and ethylene-propylene-diene terpolymer content remained unchanged with reprocessing, whereas size distribution slightly decreased. Young's modulus, yield stress, and Charpy impact strength of the composite did not significantly change even after five cycles, but deformation at break continuously decreased, and it was attributed to the slight molecular weight, talc, and rubber particle size reduction. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1195-1201, 2009