Towards understanding the role of peroxide initiators on compatibilization efficiency of thermoplastic elastomers highly filled with reclaimed GTR

Abstract

Thermoplastic elastomers based on recycled high density polyethylene (rHDPE) and styrene-butadiene-styrene (SBS) block copolymer were highly filled with reclaimed ground tire rubber (RR). The impact of various organic peroxides (dicumyl peroxide (DCP), benzoyl peroxide (BP) and di-tert-butyl peroxide (DB)), applied as free-radical initiators, on the processing, structure and performance properties of rHDPE/SBS/RR blends was investigated. It was found that, regardless of peroxide type, their application resulted in decrease of the sol fraction, which indicated increase of cross-link density. This was confirmed by the reduced flowability of material, expressed by noticeable changes in melt flow index that decreased in the order BP > DB > DCP. The most beneficial changes were observed for application of DCP, which led to 80% increase of tensile strength, 40% reduction of permanent set and 25% increase of hardness. Moreover, thermal stability of analyzed thermoplastic elastomers was significantly improved with onset of thermal decomposition shifted by over 40 °C. Scanning electron microscope images revealed enhancement of interactions at the interphase due to increased cross-link density, which had direct influence on the mechanical properties of thermoplastic elastomers. The results showed that processing and mechanical performance of obtained thermoplastic elastomers can be easily engineered by suitable selection of organic peroxide.