Crystallization behavior characterization and analysis of CF/PEEK thermoplastic composites

To gain a comprehensive understanding of the non-isothermal crystallization behavior of carbon fiber reinforced polyetheretherketone (CF/PEEK) composites, optimize process parameters, and enhance the structural forming quality and thermal and mechanical properties of thermoplastic composites, this study investigated the crystallization behavior of CF/PEEK thermoplastic composite materials under different cooling rates. Through conducting differential scanning calorimetry (DSC) experiments on CF/PEEK composite materials at various cooling rates, the non-isothermal crystallization behavior of CF/PEEK composite materials was analyzed using the Avrami, Ozawa, and Mo equations. The activation energy of non-isothermal crystallization was determined, and the crystallization kinetics model was developed. In addition, in-situ detection of the CF/PEEK composite material melting/crystallization process was carried out using fiber Bragg grating (FBG), and the strain variation mechanism during the polymer matrix melting/crystallization process was analyzed in conjunction with the crystallization kinetics model. The results indicate that the crystallinity of CF/PEEK composite materials decreases with increasing cooling rate, accompanied by a decrease in the corresponding crystallization time. It has been demonstrated that the established crystallinity crystallization kinetic model in this study effectively analyzes the crystallization process of CF/PEEK composite materials under different cooling rate. Additionally, it can be combined with fiber Bragg grating strain detection to analyze the influence of matrix phase transition on characteristic strain during the melting/crystallization process of CF/PEEK thermo-plastic composites.