耐熱性熱可塑樹脂複合材料の炭素繊維再利用を主眼としたリサイクル方法

抄録

This study has focused on the recycling of carbon fiber-reinforced thermoplastics (CFRTP) based on polyethersulfone (PES) that have a high thermal stability from the viewpoint of reusing the carbon fibers (CFs). The first recycling method is the remolding of the CFRTP; i.e., the reuse of CFs through material reuse. From the viewpoint of collection, it is expected that the waste CFRTP is gathered in a shredded form. Therefore, shredded prepregs that simulate waste CFRTP were prepared, and discontinuous CFRTP was molded as reshaped CFRTP. The reshaped CFRTP had isotropic mechanical properties; the bending modulus and strength were 35 GPa and 400 MPa, respectively. The other recycling method is the reuse of the CFs. The matrix resin was removed by pyrolysis and chemical decomposition, and the CFs were recovered by a pyrolysis process (Re-pyro-CF) or a chemical process (Re-chem-CF). It is difficult to perfectly thermally decompose PES and it is also difficult to obtain clean surfaces of Re-pyro-CF. As the result under the optimum conditions in our work the fiber tensile strength decreased by 50% compared with fresh CF (Fre-CF). Meanwhile, Re-chem-CF depolymerized under ambient pressure using N,N-dimethylformamide could be recovered with a clean surface and its tensile strength was about the same as that of Fre-CF.