Recycling process for carbon fiber reinforced plastics with polyamide 6, polyurethane and epoxy matrix by gentle solvent treatment

Due to the complex composition of carbon fiber reinforced plastics (CFRPs), a complete and useful recovery of such composite material is a real challenge. This paper presents studies on potential solvent-based recycling processes for three CFRP samples comprising polyamide 6 (PA6), polyurethane resin (PUR) and epoxy resin (EP) matrix. Different proprietary CreaSolv® Formulations were applied in laboratory scale and under thermodynamically subcritical conditions in order to dissolve the polymeric matrix and separate the inert carbon fibers. By variation of decisive process parameters, the influence of the temperature-time-load during solvent treatment and solvent recovery was observed carefully. A complete removal of the polymer matrix of all samples was achieved by means of multi-stage solvent extraction without reducing both the length and tensile strength of the recovered carbon fibers. The recovered PA6 matrix polymer revealed no significant decline of its initial average molecular weight. For the dissolved and extracted resin matrices, feedstock recycling was identified as suitable reprocessing. All of the solvent formulations tested were recycled successfully, keeping the initial dissolution properties and, thus, being applicable in a closed loop process design.