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

Abstract

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.

Recycling of the polymer composite fillers in amino alcohol medium

“…This fact is probably conditioned by the specifics of the compounds chemical structure, such as epoxy-vinyl-ester matrixes have polystyrene bridges and the epoxy binder was produced as a result of amine curing. Works [13,14] describe the possibility of using amines as a medium for epoxy polymer recycling. The polyester matrix produced by peroxide curing is also not resistant to this amino alcohol.…”

Preparation, characterization, and bio-degradation studies of high-performance bio-based polyimides based on bicyclic diamines derived from citric acid

“…44 We speculate that OAC-PIs with carbamate groups, which can provide high rigidity/linearity and interchain interaction, favor high aggregation of molecular chains, thereby ensuring favorable backbone arrangement, rigidity robustness, and low CTE. It should be noted that such CTE values (17.4 and 18.9 ppm K À1 ) are much lower than those of conventional transparent polymers such as polyethylene terephthalate (33 ppm K À1 ), 45 polycarbonate (75 ppm K À1 ), 46 and poly(ether sulfone) (54 ppm K À1 ), 47 as well as most of the reported biomass-based polyimides (29.7-61.8 ppm K À1 ) derived from isohexides, myo-inositol, anethole or camphoric acid (Fig. 2d).…”

“Functional upcycling” of polymer waste towards the design of new materials

“…547,548 Its toughness and chemical resistance determine its applicability in electronics (smartphones and computers), optical data-storage devices (compact discs (CDs) and digital versatile disks (DVDs)), packaging (food and beverages), automotive (headlights), construction and infrastructure (panels, windows, housing and sheeting). 549,550 Although BPA is a possible xenoestrogen, over 6 Mt of PC was produced in 2019. 14,551 PC does not have its own resin identification code.…”