Direct Conversion of Waste PET to Regenerated Plastics Using Flame Retardants as Depolymerization Catalysts

초록

Polyethylene terephthalate (PET) has been extensively used in the packaging industry, particularly for the production of plastic bottles. PET wastes can be converted into monomeric and oligomeric substances through depolymerization and purification processes. Currently, the chemical recycling of waste plastics is one of the most viable environmental strategies, and the direct repolymerization of depolymerized chemicals without any purification is gaining significant attention because of its simple and cost-effective recycling characteristics. In this study, expandable graphite (EPG) and zeolites were used as glycolysis catalysts for PET depolymerization, and then the reaction product was directly used to polymerize polyurethane foams (PUFs). Both EPG and the zeolites could depolymerize PET, achieving PET conversion as high as 90% with bis(2-hydroxyethyl terephthalate) yields of > 50%. PUFs were also effectively produced from both depolymerized batches, and all PUF samples had a limiting oxygen index of > 31%, indicating high flame retardancy. Thus, EPG and zeolites can play dual roles as glycolysis catalysts and flame retardants. Additionally, this study proposes an efficient PET recycling route. © 2024, The Author(s), under exclusive licence to Korean Institute of Chemical Engineers, Seoul, Korea.

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