A study on the characteristics and thermal properties of modified regenerated carbon fiber reinforced thermoplastic composite recycled from waste wind turbine blade spar

The main materials of wind turbine blades include glass fiber and carbon fiber reinforced thermoset plastic composites (i.e., FRP and CFRP), which are made of thermosetting resin and fiber reinforcement and cannot be recycled. Now, most of the waste blades (including defective parts) are disposed of by crushing to landfills. As more and more offshore and onshore wind farms are being installed worldwide, the waste generated will bring a huge burden to the environment. In this study, a microwave‐assisted pyrolysis (MAP) recycling method was used to remove the thermoset resin in the waste CFRP spar of a wind turbine blade and successfully recycle to produce the regenerated carbon fiber (rCF). The sizing agent on the surface of the rCF will be also removed after the MAP pyrolysis, resulting in a weak interface between the rCF and resin when preparing the fiber composite. This study investigates the characteristics of modifiers for treating rCF and then used to reinforce thermoplastic resin (i.e., polyamide 66, PA66) to prepare a recyclable and environmentally friendly thermoplastic composite (CFRTP). The experimental results showed that the waste CFRP spar of the wind turbine blade could be successfully recycled rCF using the MAP process, and the carbon structure of the rCF was not damaged after MAP. Furthermore, the modifier was successfully coated on the surface of the rCF and improved the interface between the fiber and the resin. The thermal properties of the resulting rCF/PA66 CFRTP were significantly improved as a result of this modification.