The Effect of Extrusion Reprocessing on Structure and Properties of Isotactic Poly(propylene)

Summary: In this study, isotactic poly(propylene) (PP) and its nanocomposites reinforced with organic modified montmorillonite (OMMT) were subjected to five subsequent extrusion cycles, in order to simulate the effect of the processing involved with mechanical recycling on their properties. Additionally, tests were run in an attempt to explore whether the reprocessed polymers are appropriate as raw materials for several applications. It was concluded that repeated processing does not significantly affect the rheological and thermal properties, as well as the thermal stability of the above studied materials. Regarding mechanical properties, the tensile and flexural strength of the examined products remain almost unaffected. PP samples presented a decrease in tensile and flexural moduli, whereas in the case of OMMT/PP nanocomposites reprocessing improves these properties, probably due to better intercalation of clay platelets taking place upon melt mixing.