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 fiberreinforced 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 andCN-VBGE-based CFRPs underwent smooth breakdown with the treatment of hydrochloric acid in tetrahydrofuran at room temperature for 24 h 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.

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