Recyclable Carbon Fiber-Reinforced Plastics (CFRP) Containing Degradable Acetal Linkages: Synthesis, Properties, and Chemical Recycling

Two epoxy resins containing degradable acetal linkages were synthesized by the reaction of cresol novolak-type phenolic resin (CN) with vinyl ethers containing a glycidyl group [cyclohexane dimethanol vinyl glycidyl ether (CHDMVG) and 4-vinyloxybutyl glycidyl ether (VBGE). Carbon fiber-reinforced plastics (CFRPs) were prepared by heating laminated prepreg sheets with CN-CHDMVG resin (derived from CN and CHDMVG) and CN-VBGE resin (derived from CN and VBGE), in which carbon fibers are impregnated with epoxy resins containing curing agents [dicyandiamide (DICY)] and curing accelerator [3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)]. CN-CHDMVG-based CFRPs and CN-VBGE-based CFRPs exhibited almost the same tensile strength as the conventional bisphenol-A-based CFRPs. CN-CHDMVG-based CFRPs and CN-VBGE-based CFRPs underwent smooth breakdown with the treatment of hydrochloric acid in tetrahydrofuran at room temperature for 24h to regenerate strands of carbon fibers. The surface conditions of the recovered carbon fibers had little changes during degradation and recovery processes on the basis of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The recovered carbon fibers exhibited almost the same tensile strength as virgin carbon fibers and hence would be reused for the production of CFRPs. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1052-1059