Nvestigation of the effect of recycling process parameters on the rheological and mechanical properties of polypropylene

In this study, the effects of processing conditions on the rheological and mechanical properties of polypropylene (PP) polymer during recycling were examined. Two different types of polypropylene homopolymers, used in industrial-scale extrusion and injection molding, were recycled three times at different temperatures in a single-screw extruder. After granulating the obtained products, film sheets were produced using a hot press. The crystallization behaviors of the prepared granules were analyzed under non-isothermal conditions using Differential Scanning Calorimetry (DSC). In the rheological analysis of the granule-form products, the effects of the number of recycling cycles and temperature differences on molecular weight, viscosity, and melt-state viscoelastic properties were examined by applying a frequency sweep test. Additionally, the impact of the recycling process parameters on the deformation rates and solid-state viscoelastic behaviors of the materials under long-term use conditions was evaluated by conducting tensile and creep tests on the products produced in film form at different temperatures.