Water-based PEKC-COOH sizing agent for enhancing the interfacial adhesion of carbon fiber/polyether-ether-ketone composites

Improving the dissatisfactory interfacial adhesion of carbon fiber (CF)/polyether-ether-ketone (PEEK) composites in some specific conditions is an extremely urgent demand. In this work, a series of soluble phenolphthalein polyaryl-ether-ketone polymers with different carboxyl contents (PEKC-COOH) were synthesized and employed to prepare water-based sizing agents. PEKC-COOH showed high solubility and excellent thermal properties, with over 239.5 degrees C of T-g value, which were much higher than that of PEEK (148.4 degrees C). The sizing agents exhibit good storage stability with particle sizes between 60.6 and 75.0 nm. Compared to unsized CF/PEEK composites, the bending strength and interlaminar shear strength of the CF-5/PEEK composites were enhanced by 52.9% and 53.3%, respectively. An illustrative mechanism for the interfacial reinforcement effect of the sizing agent was proposed accordingly. The protocol provides an effective and green method towards water-based sizing agent for enhancing the interfacial properties of CF/PEEK composites.

Automated summary

In this study, soluble phenolphthalein polyaryl-ether-ketone polymers were synthesized and used to prepare water-based sizing agents, significantly improving the interfacial adhesion of CF/PEEK composites. The sizing agents showed high solubility, excellent thermal properties, and good storage stability, leading to a significant enhancement in bending strength and interlaminar shear strength of the composites. An illustrative mechanism for the interfacial reinforcement effect of the sizing agent was proposed, providing an effective and green method for enhancing the interfacial properties of CF/PEEK composites.