Evaluating the environmental impacts of graft copolymer prepared by conventional emulsion polymerization, electron beam irradiation, and gamma ray irradiation through life cycle assessment

Abstract

Graft copolymer of natural rubber (NR) and styrene to used as a blend with styrene-butadiene for green tire can be produced via three techniques: emulsion polymerization (EP), electron beam irradiation (EB), and gamma ray irradiation (GR). Products from all techniques had similar cross-linking properties; leading to similar mechanical properties. Therefore, producing the graft copolymer using less resources is the best choice as it is a cleaner production. This paper compared the environmental impact assessment of these three production processes. SimaPro version 7.3 software using Eco-indicator 99 method for environmental impact assessment was used throughout this study. The functional unit (FU) used was 100 g of grafted rubber product, with the considered system boundary starting from raw materials for the production of a specified product and continuing to the end of copolymerization processes (cradle-to-gate). The results indicated that, at the laboratory scale, the EB technique had the largest contribution of environmental impacts, followed by EP and GR techniques. However, operating at the maximum capacity led to an overall reduction of all impacts. The reduction was improved by 86.32% for EB and by 60.5% for GR. However, production by EB still contributed the highest overall environmental impact, while GR contributed the least. In decreasing order of significance, the main impacts of EB were resources (R), human health (HH), and ecosystem quality (EQ). The essential factors which caused these impacts were, in decreasing order of significance, the usages of electricity, NR, and styrene. Therefore, GR method was the choice for scaling up the green production process in both saving the electricity usage and for improvement in the environmental impacts.