THERMOPLASTIC VULCANIZATES BASED ON DYNAMICALLY VULCANIZED POLYPROPYLENE/CARBOXYLATED NITRILE RUBBER BLENDS

Abstract

ABSTRACT Thermoplastic vulcanizates (TPVs) based on polypropylene (PP) and carboxylated nitrile rubber (XNBR) with improved mechanical properties were prepared by dynamic vulcanization using dicumyl peroxide (DCP) in combination with N,N′-m-phenylene-bis-maleimide (BMI) as a cross-linking system. The effect of PP grafted with maleic anhydride (PP-g-MA) or with glycidyl methacrylate (PP-g-GMA) and triethylene-tetramine (TETA) as the compatibilizing systems on the mechanical, morphological, and dynamic mechanical properties of PP/XNBR blends was investigated. Experimental results revealed that PP-g-GMA has a better compatibilizing efficiency. Tensile strength and elongation at break presented a significant improvement with the addition of 2.5 to 7.5 phr of this functionalized PP. The improvement of the tensile properties was observed for all blend compositions studied. Also the tensile properties of the blends did not change considerably after three reprocessing cycles, confirming the efficiency of this system as a TPV. The presence of PP-g-GMA also resulted in an increase of the apparent melt viscosity of the corresponding TPVs, confirming the reactive compatibilization. A decrease in rubber particle size with the presence of PP-g-GMA was also observed by scanning electron microscopy.