Solvolysis process for recycling carbon fibers from epoxy‐based composites

Fiber reinforced polymers boast exceptional mechanical performance coupled with low material density. Over recent decades, their usage has been steadily increasing and is poised to accelerate in the future. These materials typically have a lifespan of around 25-30 years, so at present time lots of tons of polymer composites are next to their end of life and this volume continues to grow. Currently, a significant portion of these materials is either incinerated or landfilled, resulting in substantial environmental impacts. Numerous studies have aimed to identify optimal recycling approaches, one of which involves solvolysis: the chemical dissolution of the polymer matrix. In this study, a solvolysis method has been devised and refined to effectively recover carbon fibers from composites while minimizing property degradation. The process begins with the identification of a suitable solvolysis fluid, specifically an aqueous sulfuric acid solution. Subsequently, key solvolysis parameters including solution concentration, temperature, residence time, and fluid agitation are meticulously optimized. The chemical and morphological impacts of this process are thoroughly examined using Fourier-transform infrared spectroscopy analysis and scanning electron microscope observations.