Design of recycling system for poly(methyl methacrylate) (PMMA). Part 1: recycling scenario analysis

• Published in: The international journal of life cycle assessment Vol. 19; no. 1; pp. 120 - 129
• Main Authors: Kikuchi, Yasunori, Hirao, Masahiko, Ookubo, Takashi, Sasaki, Akinobu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.01.2014; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: chemical hazards; Closed-loop recycling; Commodities; Earth and Environmental Science; Emissions; Environment; Environmental Chemistry; Environmental Economics; Environmental Engineering/Biotechnology; Environmental impact; fossils; greenhouse gas emissions; Greenhouse gases; inventories; Lca of Waste Management Systems; Life cycle analysis; Life cycle assessment; Life cycle engineering; Life cycles; material flow analysis; Mathematical models; Monomers; Plastics; polyethylene; Polymethyl methacrylates; Polymethylmethacrylate; Polypropylene; polypropylenes; Recycling; Recycling systems; Resins; Resource availability; Resource consumption; Sensitivity analysis; Simulation; Waste treatment; Wastes; Highly functional plastics; PMMA pyrolysis; Simulation; Plastic grade; Operational modification
• ISSN: 0948-3349; 1614-7502
• DOI: 10.1007/s11367-013-0624-y

INTRODUCTION: In this series of papers, we present a poly(methyl methacrylate) (PMMA) recycling system design based on environmental impacts, chemical hazards, and resource availability. We evaluated the recycling system by life cycle assessment, environment, health, and safety method, and material flow analysis. PURPOSE: Previous recycling systems have not focused on highly functional plastics such as PMMA, partly because of lower available volumes of waste PMMA compared with other commodity plastics such as polyethylene or polypropylene. However, with the popularization of PMMA-containing products such as liquid crystal displays, the use of PMMA is increasing and this will result in an increase in waste PMMA in the future. The design and testing of recycling systems and technologies for treating waste PMMA is therefore a high research priority. In this study, we analyze recycling of PMMA monomers under a range of scenarios. METHODS: Based on the differences between PMMA grades and their life cycles, we developed a life cycle model and designed a range of scenarios for PMMA recycling. We obtained monomer recycling process inventory data based on the operational results of a pilot plant. Using this process inventory data, we quantified life cycle greenhouse gas (LC-GHG) emissions and fossil resource consumption, and we calculated the LIME single index. RESULTS AND DISCUSSION: PMMA produces more than twice the amount of GHG emissions than other commodity resins. Through scenario and sensitivity analyses, we demonstrated that monomer recycling is more effective than mechanical recycling. Operational modifications in the monomer recycling process can potentially decrease LC-GHG emissions. CONCLUSIONS: Highly functional plastics should be recycled while maintaining their key functions, such as the high transparency of PMMA. Monomer recycling has the potential to achieve a closed-loop recycling of PMMA.