Sustainable Recycling of Thermoset Polymers: A DOE-Based Approach to Optimize Solvolysis of Glass Fiber-Reinforced Epoxy Composites

Abstract Thermoset polymers and their composites are widely used in various industries because of their exceptional mechanical properties and durability. However, their three-dimensional cross-linked structure poses significant challenges for recycling at the end of their life cycle. This study investigates the recyclability of thermoset polymers using chemical recycling methods, particularly solvolysis. This study explores different solution media for recycling glass fiber-reinforced epoxy (GFRE) composites to identify the most effective approach. A systematic evaluation of various solvents was conducted to determine their efficiency in breaking down the polymer matrix and recovering valuable fibers. Furthermore, the Design of Experiments (DOE) methodology using Design Expert software was employed to optimize the solvolysis process. The optimization focused on three critical parameters: reaction temperature, reaction time, and sulfuric acid concentration. The optimal conditions for achieving the highest recycling yield were identified as a reaction time of 48 hours, a sulfuric acid concentration of 100% , and a reaction temperature of 87.5°C. This study determined the best conditions to maximize GFRE composite recycling efficiency through the analysis of key parameter interactions. These findings support the development of more sustainable thermoset recycling practices, offering solutions for reducing environmental impact and recovering resources from composite waste.