Review on recycling of carbon fibre reinforced thermoplastics with a focus on polyetheretherketone

Addressing the waste management of carbon fibre-reinforced thermoplastics, we review the different recycling routes, emphasising the mechanical recycling route of carbon fibre-reinforced polyetheretherketone (CF-PEEK). The most promising scheme for CF-PEEK is mechanical comminution, followed by long fibre-reinforced thermoplastics compression moulding. The main reasons are cost-efficiency and low environmental impacts, as it preserves the valuable matrix while enabling good mechanical properties. In this paper, we discuss the mechanical recycling route in general and then focus on the compression moulding step. Furthermore, we explore the effect on the mechanical properties to gain insights into potential fields of application for the mechanically recycled CF-PEEK. We also review the effect of CF-PEEK chemical degradation arising during compression moulding on the overall properties of the recyclate. Understanding the mechanisms and changes in the fibre, matrix and fibre-matrix interface during recycling is crucial for optimising the process and maximising the number of recycling cycles.