Pre-compositing polyetherketoneketone with short-cut carbon fibers into advanced powder materials toward composites with fully-adhered interfaces

It is challenging to realize intimate interface between reinforcement and matrix using powder materials, due to the high melting points and melt viscosities of thermoplastics like polyaryletherketones. Herein, a solution-based strategy is proposed to prepare pre-composition in powders, and using them, full and tight fiber–matrix bounding is formed in the final composites. Owing to the dissolubility of polyetherketoneketone (PEKK), short-cut carbon fibers (CFs) are uniformly introduced into the solution and fully covered by PEKK, i.e., the pre-composition. The composite powders lead to structural uniformity, full utilization of CF surfaces, and avoidance of CF aggregation. The hot-compressed beams exhibit remarkably enhanced tensile and flexural strengths (135.5 and 173.7 MPa), more than 30% and 60% higher than those of the pure PEKK. Meanwhile, they possess high tensile and flexural strains at break up to 5.5% and 11.4%, respectively, enhanced crystallinity up to 17.7%, and high thermal conductivity of 0.26–0.29 W m−1 K−1. The pre-composition also exhibits other advantages, such as the higher powder flowability, reduced steps of high-temperature processing, and superior anti-abrasion ability and enhanced thermal stability of composite beams.