Micromechanical Mechanisms for Toughness Enhancement in β-Modified Polypropylene

摘要

Two samples of isotactic polypropylene (iPP) representing the crystalline α- and β- modifications are compared with regard to their semicrystalline morphology and the resulting micromechanical mechanisms. Processes at room temperature (23°C) and at -40°C have been investigated by means of different microscopic techniques. Good results can be achieved by the application of a chemical etching technique to the deformed samples prior to scanning electron microscopy inspection. The toughness enhancement that is measured for the β-iPP is attributed to micromechanical mechanisms initiated within the intercrystalline, amorphous phase. It is shown that the specific nanostructure (lamellar arrangement) causes significant changes in the mechanical behaviour of the materials.