Preparation and properties of carbon fiber reinforced bio-based degradable acetal-linkage-containing epoxy resin composites by RTM process

The recycling of carbon fiber (CF) reinforced bio-based degradable epoxy resin composites is of great significance for resource saving, environment protection and sustainable development of economy and society. Resin transfer molding (RTM) has been recognized as one of the most promising processes to manufacture CF Reinforced polymeric composites cost-effectively. The bio-based diglycidyl ether pentaerythritol vanillin diacetal (DEPVD) epoxy resin used in this study is an epoxy resin that can be degradable under mild conditions. And its CF composites were prepared by the RTM process using DDS as a curing agent and low viscosity bisphenol A-E51 epoxy resin as a diluent. The chemical rheological properties, curing behavior, thermal stability, dynamic viscoelasticity and mechanical properties of DDS-E51-DDS epoxy resin were investigated. It is found that the increase of DEPVD content is beneficial to improve the mechanical properties, T-g and solid residue after thermal degradation of DEPVD-E51-DDS epoxy resin. Moreover, the effects of DEPVD content in epoxy resin on the mechanical properties of CF/DEPVD-E51-DDS composites were evaluated. When the DEPVD content is 70%, the tensile and flexural strength of CF/EPVD-E51-DDS composites are 1649.4 MPa and 1207.4 MPa, respectively. The degradability and mechanism of CF/DEPVD-E51-DDS composites were further investigated. CF/DEPVD-E51-DDS composites containing 70% DEPVD have excellent degradability, and the recycled CFs exhibit comparable mechanical properties to the virgin CFs, which demonstrates a novel way to recover the high-quality of used CFs.