Polyolefin nanocomposites: Formulation and development

Abstract

Abstract The preparation of nanoclay‐reinforced polypropylene nanocom posites by means of melt processing was investigated. In order to optimize the dispersion of the nanoclay and the nanoclay‐matrix interface, experiments were performed with three different nanoclays, two different maleic‐anhydride–grafted PP coupling agents, and two different mixing procedures. The physicochemical and mechanical properties of the prepared samples were characterized by means of various techniques. The coupling agents increase the degree of clay intercalation and exfoliation, the latter resulting in part from a “peeling off” mechanism. Significant improvements in tensile and flexural strength and modulus are obtained with Cloisite® 15A nanoclay and a coupling agent characterized by high molecular weight and low grafting content, and these improvements are also accompanied by an increase in Izod impact strength. Little difference was observed between the two mixing procedures used. The improvements were not as pronounced when the coupling agent was characterized by low molecular weight and high grafting content, or when Cloisite® 30B nanoclay was used. In the latter case, there was evidence of greater thermal instability than for Cloisite® 15A. Polym. Eng. Sci. 44:1212–1219, 2004. © 2004 Society of Plastics Engineers.