Abstract
Techniques for the decomposition and dissolubility of epoxy resin and the recovery of carbon fiber in carbon fiber reinforced plastic (CFRP) are introduced. In the case of supercritical water as a solvent, epoxy resin was decomposed into small molecules, including phenolic compounds, at 380 °C, 25 MPa with a 30 min reaction time. When supercritical methanol was used as a solvent at 270 °C, 10 MPa in 60 min, the acid anhydrate curing thermosetting epoxy resin decomposed into methanol-soluble resin, which kept the backbone structure of thermosetting epoxy resin due to the selective decomposition of the bridged structure. Furthermore amine curing thermosetting epoxy resin decomposed completely using high-temperature acetone steam at 320 °C, 1 MPa in 20 min. The tensile strengths of the recovered carbon fibers at these conditions were slightly decreased by 7-9 %, as compared to the virgin fiber. The carbon fiber sheets recovered by supercritical methanol using a bench-scale plant could be used to make a recycled CFRP by mixing virgin epoxy resin and cross-linker. The strength of the recycled CFRP was close to that of virgin CFRP.
