Effect of Recycled Polypropylene on the Mechanical and Rheological Properties of Polypropylene-NBR Thermoplastic Vulcanisates

Abstract

Virgin polypropylene (PP), recycled polypropylene (RPP) and acrylonitrile butadiene rubber (NBR) were mixed together to prepare ternary blends (PP/RPP/NBR) of thermoplastic vulcanisates (TPVs). The blends comprised 30 parts per hundred (phr) NBR and 70 phr PP and RPP. Sulphur was used to dynamically crosslink the NBR during the blending process. Maleic anhydride grafted polypropylene (MA-g-PP) was used as compatibiliser to enhance the interaction of the polypropylene and the rubber. In this study, the loading of RPP in the TPVs was varied and the effects on mechanical and rheological properties were studied. The hardness and the tensile strength of the TPVs increased upon increasing the RPP loading. The RPP exhibited an adverse effect on elongation-at-break of the vulcanisates, with the pseudo-plastic flow behaviour and the viscosity of the vulcanisates increasing with the increased loading of RPP.