Dynamic vulcanization and propreties of polypropylene/reclaimed tire rubber blends

Abstract

The current research involved the blending of reclaimed tire rubber (RTR) and polypropylene (PP). Dynamic vulcanization of blend was performed by using sulphur system. The crosslink density of RTR was determined by solvent swelling test. Additionally, RTR weight loss on heating and RTR rubber components were determined by means of thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR), respectively. All blends were prepared in an internal mixer and were compression-molded. Their mechanical properties were then determined. The phase structures of the two components in the blend at various ratios were investigated using scanning electron microscope (SEM). Rheological behavior of blends was also studied to understand the effect of shear rate on the flow behavior and the elasticity of the materials. The effects of a RTR content, type of compatibilizers, and the addition of virgin natural rubber and ethylene propylene diene (EPDM) on mechanical and rheological properties of RTR/PP blends were investigated. RTR/PP blend with a ratio of 30:70 was found to show the optimum properties. An addition of compatibilizer did not significantly improve the mechanical properties of the blends. The highest impact strength was observed when EPDM of 30 phr was introduced to the blend, while a maximum elongation was found for the blend with NR of 30 phr. Furthermore, it was shown that the studied RTR/PP blends could be reprocessed. The resulting blends seemed to possess slightly rubber-like properties while they could be melt-processed like thermoplastic polymers.