Preparation and Degradation of Waste Polycarbonate-Derived Epoxy Thermosets and Composites

Abstract

We report a robust, 100% atom-efficiency strategy for preparing waste polycarbonate (WPC)-derived epoxy resin. To demonstrate the preparation process, we perform a pyridine-catalyzed model reaction between diphenyl carbonate (DPC) and diglycidyl ether of bisphenol A (DGEBA) in a molar ratio of 1:2. After epoxy-equivalent titration and two-dimensional nuclear magnetic resonance (2D-NMR) analysis, we confirm that the product is bis­(1-(4-(2-(4-(oxiran-2-ylmethoxy)­phenyl)­propan-2-yl)­phenoxy)-3-phenoxypropan-2-yl) carbonate (DPC-EP2). Based on the model reaction, three WPC-based epoxy resins (WPC-EPX, X = 2, 3, and 4) were prepared by the reaction of WPC with DGEBA in a molar ratio of 1:2, 1:3, and 1:4 in the presence of pyridine. The WPC-EPX epoxy resins were cured with WPC, phenol novolac (PN), diamino diphenylmethane (DDM), and dicyandiamide (DICY). The mechanical and thermal properties of the thermosets were discussed. We also prepared epoxy/carbon fiber composites and investigated the degradation of epoxy thermosets and the recycling of the carbon fiber. When the WPC-EP2 epoxy resin was cured with WPC, it can be successfully degraded to a phenoxy resin and 1,3-dihyexylurea through a catalyst-free aminolysis process. Undamaged carbon fibers have been recycled, according to the scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) and tensile stress–strain data. The transformation of WPC to WPC-EPX, the aminolysis of WPC-EP2/WPC to a phenoxy resin and 1,3-dihexylurea, and the recycling of carbon fiber in the composite have been successfully demonstrated. Therefore, we believe that this work contributes greatly to the field of “sustainable approaches in waste utilization.”

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.…”

Glycidyl Carbamate Resins Synthesized through a Nonphosgene Route by Amidine-Based Superbases Using Recycled Polycarbonate

“…Therefore, an alternative approach to chemical recycling may offer solutions for the reuse of wPC as a value-added chemical or a starting material for the development of new polymeric products. A range of wPC treatments, such as pyrolysis, − hydrolysis, − alcoholysis, − aminolysis, − and catalyzed transformation − have been reported for polymer recovery to various products. However, harsh environments, such as alkaline water or superheated steam, are typically required during the recycling process, and the use of harsh reagents at high temperatures is associated with complex products.…”

Closed‐Loop Recycling of Poly(Imine‐Carbonate) Derived from Plastic Waste and Bio‐based Resources

“…Recently, Sardon and coworkers demonstrated the organocatalyzed depolymerization of BPA-PC into various heterocycles, [20] diols, [21] and bis-imidazole [22] as value-added feedstocks. In addition, upcycling of polycarbonates paves the way for the manufacture of novel polymers, such as poly(aryl ether sulfone)s, [23] bicyclic diol based polycarbonate, [24] epoxy resins, [25,26] polyurethanes, [27] and non-isocyanate polyureas. [28] Despite these excellent strategies to obtain innovative materials by upcycling of polycarbonates, the recyclability of the newly formed polymers, to our surprise, has never been investigated.…”