Multifield computational model of chemical recycling of polymer composites: Temperature effects on solvolysis efficiency and energy consumption

Abstract

As a promising recycling technology for fiber-reinforced composites (FRCs), solvolysis effectively separates fibers from their polymer matrix. Understanding and predicting the solvolysis process of composites is essential for optimizing recycling technologies and planning end-of-life strategies. This paper proposes a multifield computational model that integrates diffusion, chemical reaction, temperature distribution, and mechanical responses, with a focus on the effect of temperature during solvolysis. The coupled model was numerically implemented using the finite element method and calibrated with experimental data from solvolysis of epoxy resin at various temperatures. The effects of fiber placement and fiber volume fraction on solvolysis was examined using the computational model. Results show that higher fiber volume fractions lead to slower solvolysis, which can be explained by fibers acting as barriers to solvent diffusion into the polymer. The influence of temperature on fiber degradation and energy consumption was also investigated by incorporating an empirical strength degradation equation and a heat conduction model. The strength of recovered fibers decreases from 99 % at 85 °C to 85 % at 300 °C within 40 h, while the energy consumption for solvolysis at 145 °C is 20 % higher than at 85 °C. The findings suggest that optimizing solvolysis conditions, particularly temperature, is crucial for balancing recycling efficiency and maintaining fiber integrity.