Application of recycled carbon-fibre-reinforced polymers as reinforcement for epoxy foams

The ever-increasing demand for carbon fibre reinforced polymers (CFRP) and stringent environmental legislation have driven the research into recycling and reusing the CFRP waste. This paper presents a mechanical recycling process of CFRP and the application of the recyclates as reinforcement for epoxy foams. The CFRP was mechanically processed using a jet mill. Up to 10 wt% of the CFRP recyclates, without separation of fibre-rich portion and resin-rich portion, was added into epoxy foams. The compressive modulus and strength of the epoxy foams increased from 288 MPa and 7.0 MPa, respectively, to 1060 MPa and 22.8 MPa, respectively, accompanied with an increase in foam density from 0.37 g cm^-3 to 0.68 g cm^-3. Consequently, the specific compressive modulus and strength (normalised against density) increased from 789 MPa cm³ g^-1 and 19.1 MPa cm³ g^-1 for unreinforced foam to 1563 MPa cm³ g^-1 and 33.5 MPa cm³ g^-1 for CFRP recyclates reinforced foam, representing a 98% and 75% improvement, respectively. These results demonstrate that the CFRP recyclates have excellent reinforcing ability for epoxy foams.