Tailoring PS/PPrecycled blends compatibilized with SEBS. Evaluation of rheological, mechanical, thermomechanical and morphological characters

Abstract

The increasing consumption of polypropylene (PP) in several practical applications contributes to the production of a large amount of post-consumer and post-industrial waste contributing to environmental damages. The practice of material reusing is one of the feasible alternatives to overcome problems generated by these wastes/post-consumer products. Therefore, the effect of recycled polypropylene (PPr) addition in polystyrene (PS)/polypropylene (PPv) blends, compatibilized with styrene-(ethylene/butylene)-styrene (SEBS) was performed in this study. Blends were compounded in a co-rotational twin screw extruder; afterwards extruded granules were injection molded to produce specimens for tensile experiments. Blends were characterized by parallel plate rheometry, mechanical properties, impact strength, differential scanning calorimetry (DSC), thermogravimetry (TG), heat deflection temperature (HDT) and scanning electron microscopy (SEM). According to complex viscosity data blends behave as pseudoplastic fluid. An increase in impact strength, elongation at break, thermal stability (TG) and HDT was observed in relation to neat PS. Nevetheless, there were losses in the elastic modulus and tensile strength. The morphologies investigated by SEM are typical of immiscible blends corroborating Cole-Cole plots. In the range of investigated compositions for PPr (7, 14, 21 and 35% by mass), no significant differences in the blends properties were verified. Summing up, results collected with this work are valuable for recycling’s researches, which can lead to savings in the final product, since it was used up to 35% PPr, whereas keeping high performance and reconciling economic and environmental purposes.