Influence of electron beam irradiation on crosslink behaviour of reclaimed tire rubber/EVA blend in the presence of radiation sensitizers

Abstract

Non-degradable waste tire generation around the world is growing at an alarming rate. Diversifying the recycling route of these waste tires is essential to solve the problem. To address the issue, this study utilized radiation sensitizers and electron beam irradiation to enhance the poor properties of reclaimed waste tire rubber/poly(ethylene vinyl acetate) (RTR/EVA) blend. The RTR, EVA and radiation sensitizers were mixed in the internal mixer followed by electron beam (EB) irradiation with doses ranging from 50 to 200 kGy. Radiation sensitizers loading was fixed at 4 wt%. The degradation and stability in RTR were studied in term of crosslink behaviour upon irradiation. Electron beam irradiation revealed the presence of radical stabilizing and scavenging additives within RTR which retards the crosslinking process in RTR and the blends. RTR, EVA and the RTR/EVA blend suffered from further oxidative degradation from irradiation in air. Radiation sensitizers, trimethylol propane triacrylate (TMPTA) and tripropylene glycol diacrylate (TPGDA), were used to accelerate the irradiation induced crosslinking in RTR and the RTR/EVA blend. Presence of radiation sensitizers leads to enhanced crosslink formation within RTR and the RTR/EVA blend. These findings validated the feasibility of using ionizing radiation in the presence of radiation sensitizers for recycling inferior waste polymers into higher quality material.