Mechanical and Thermal Degradation Properties of Isotactic Polypropylene Composites with Cloisite15A and Cloisite20A

Abstract

In this work, the influence of maleic anhydride grafted polypropylene (PP-g-MA) content on thermal and me-chanical properties of polypropylene (PP) composites with two types of clays, differing modifier density in the interlayer space, Cloisite15A and Cloisite20A, was studied. PP/clay composites were melt blended in presence of different content of PP-g-MA from 3, 6, 9, and 12 wt.%. It was found that Cloisite15A with a high density of the modifier promotes the formation of intercalated structures, while Cloisite20A with a low density of the modifier, predominantly exfoliated nanocomposites are formed. In the first case, the structure tends to become intercalated whilst composites with Cloisite20A favor the formation of predominantly exfo-liated structures. The formation of the nanocomposite is accompanied by a significant increase in thermal sta-bility (50 % weight loss is observed at temperatures of 360 °C and 430 °C for polypropylene and nanocompo-sites based on it, respectively). An analysis of the mechanical properties of nanocomposites generally indi-cates an increase in the elastic modulus by 15–20 %, and this effect is more pronounced for exfoliated struc-tures, the yield strength practically does not change, and the elongation at break decreases very noticeably.