Recycling of carbon fibre reinforced epoxy resin composites under various oxygen concentrations in nitrogen–oxygen atmosphere

• Thermolysis of carbon fibre reinforced epoxy resin in nitrogen–oxygen atmosphere.
• Temperature, oxygen concentration and reaction time are important factors.
• About 80% of tensile strength and modulus was preserved at optimum conditions.

Pyrolysis is a common method for recycling carbon fibre reinforced polymer composites. However, carbonized residue is preferred to form on fibre surface. Thermal processing in air could eliminate the carbonized residue but the mechanical strength of the inherent fibre tends to be damaged by oxidation. Here, we investigated the influence of the temperature, oxygen concentration in nitrogen and time on the thermal decomposition of carbon fibre reinforced 4,4′-diaminodiphenylmethane cured epoxy resin composite and properties of the recycled carbon fibres. The properties of the recycled carbon fibre were characterized using single tensile test, SEM and XPS. Temperature, oxygen concentration and reaction time appear to be the important factors to tensile strength of the recovered carbon fibres. About 80% of tensile strength and modulus was preserved at optimum conditions. Gas and liquid products from DDM cured epoxy resin were also analysed in nitrogen and 5% O2–95% N2.