Characterization of the interfacial properties of modified polypropylene

Abstract

The interfacial properties of a rubber blended polypropylene were investigated by the combination of complementary techniques in order to characterize the effects of different surface treatments. The wettability was investigated by contact angle measurements with water, streaming potential measurements indicated the Brønsted acidity/basicity of the surfaces, and X-ray photoelectron spectroscopy (XPS) identified the chemical elements, which were incorporated by the various treatments. The topography and the roughness of the samples were quantitatively analyzed by scanning force microscopy (SFM). Direct force measurements showed the possibility of changing the sign of the surface charge by choosing suitable buffer solutions, leading to attraction and repulsion to the Si₃N₄ tip, respectively. In the case of technical-type polymer samples used in this study, direct force measurements are in exact agreement with the streaming potential measurements and offer a valuable tool for interface characterization.