Cavitation phenomenon and mechanical properties of partially disentangled polypropylene. (29th August 2018) - Pawlak, Andrzej
Abstract: The mechanical properties of polypropylene samples with three different densities of macromolecular entanglements were examined in tensile test. The experiments were performed at temperatures of 20–100 °C. SAXS, WAXS, DSC and SEM techniques were used to study the evolution of polypropylene internal structure with deformation. It was found that properties of polymer at yield were not changed by reduction of entanglements. The strain hardening phase of deformation depended on the density of molecular network formed by entanglements and the increase of stress was faster when polypropylene is more entangled. It was observed enhanced cavitation in partially disentangled polypropylene. The cavitation in disentangled polymer was possible not only at low temperatures, but even when the tensile deformation was performed at temperature of 100 °C. Graphical abstract: Image 1 Highlights: The reduction of macromolecular entanglements significantly modifies tensile properties of polypropylene. The cavitation is intensified in less entangled PP and is possible in high temperature. Strain hardening is stronger when the polymer is more entangled.