Catalyst-assisted reconstruction of recycled epoxy resins with restored mechanical performance

Abstract

Chemical recycling has emerged as a promising approach in polymer recycling strategies due to its capacity for depolymerization, structural selectivity, and its pivotal role in advancing the development of sustainable recycled materials. However, recycled resins often exhibit inferior mechanical properties compared to their pristine counterparts. This study investigates the incorporation of a linear toughening agent, neopentyl glycol diglycidyl ether (LTA), in conjunction with ferric chloride (FeCl₃), a Lewis acid catalyst, to enhance the performance and reusability of recycled epoxy resins. Recycled resins obtained via catalytic degradation were compounded with pristine resin, LTA, and FeCl₃. The incorporation of LTA facilitated the formation of linear bridges between polymer chains, promoting effective crosslinking. The combined structural and mechanical results, including reduced swelling ratios, diminished -OH intensity in FTIR, and the incorporation of LTA, as confirmed by 13C NMR, suggest a more efficiently crosslinked network structure within the recycled resin matrix. Concurrently, FeCl₃ catalyzed esterification and crosslinking reactions between epoxy groups and anhydride curing agents, further contributing to network formation. Experimental findings revealed that the combined use of LTA and FeCl₃ significantly improved the tensile strength, thereby restoring the mechanical integrity of recycled epoxy resins and demonstrating their potential for reuse following mechanical recovery.

keywords: Epoxy resin, FeCl3 catalyst, Linear toughening agent, MEA/KOH, Recycling.