Recycling carbon fibers by solvolysis: Effects of porosity and process parameters

Chemical recycling, also known as solvolysis, is one of the most promising strategies for recycling fiber-reinforced thermosetting composite materials, due to its ability to recover nearly undamaged fibers for reuse. This approach is particularly appealing for carbon fibers, which have a high environmental production cost. However, there is a lack of understanding of the modelling and optimization of reaction conditions that would be required for the widespread use of this technology. This study explores how different solvolysis conditions and manufacturing-induced porosity influence the efficiency of the solvolysis process in epoxy-based carbon fiber composites. The goal is to enhance understanding of the process to enable more efficient material recovery. A comprehensive series of experiments was conducted, varying solvolysis process parameters, fiber volume fractions in the composites, and solvent concentrations. The effects of voids within the composite materials on solvolysis efficiency were investigated through numerical analysis, incorporating an anisotropic diffusion coefficient into the model. The results reveal that the quality of the material significantly affects the overall rate of solvolysis. The findings suggest that understanding the role of voids and the relationship between composite quality and solvolysis can improve the efficiency of composite recycling, contributing to more sustainable lifecycle management of these materials.