Recycling Waste Polycarbonate to Bisphenol A-Based Oligoesters as Epoxy-Curing Agents, and Degrading Epoxy Thermosets and Carbon Fiber Composites into Useful Chemicals

We prepared two phenylacetate end-capping oligoesters from recycled bisphenol A (RBPA), which is obtained from a phase-transfer agent-assisted basic degradation of waste polycarbonate (WPC). The two oligoesters were successfully applied as epoxy-curing agents. The curing of oligoesters with epoxy is based on the chemistry of a 4-dimethylaminopyridine (DMAP)-catalyzed model reaction of phenyl benzoate and glycidyl phenyl ether. Mechanical and thermal properties of oligoesters/epoxy-cured thermosets were investigated and discussed. Glass transition temperatures ( T g ), the coefficient of thermal expansions (CTE), thermal decomposition temperatures ( T d5% ), and tensile strengths of four thermosets are, respectively, in the ranges of 140 to 180 °C, 37 to 72 ppm/°C, 396 to 431 °C, and 49 to 73 MPa. We also prepared carbon fiber composites (CFRPs) by using oligoester/epoxy resin, which could be effectively degraded to phenoxy resin using a catalyst-free aminolysis technique, and undamaged carbon fibers could be recycled without sacrificing mechanical strength or chemical composition. Processes such as recycling of WPC into bisphenol A-based oligoesters as epoxy-curing agents and degrading the epoxy thermosets and CFRPs into useful chemicals have been achieved.