Synergistic interface Engineering: Electrochemically activated carbon fiber surface and matrix Transcrystallization in PAEK composites

The development of carbon fiber reinforced poly ether ether ketone (PEEK) composites (CF/PEEK) is often impeded by the inadequate interfacial bonding between the carbon fibers (CF) and the PEEK matrix. This study presents a novel approach to enhance the interfacial properties of CF reinforced poly aryl ether ketone (PAEK) composites (CF/PAEK) by introducing a low melting temperature poly aryl ether ketone (LM-PAEK) matrix and modifying the CFs through electrochemical oxidation. The synthesized LM-PAEK, enriched with biphenyl groups, demonstrated a reduced melting point and altered crystallization behavior compared to conventional PEEK. The modification of CFs led to an increase in surface roughness and the introduction of active functional groups, which bolstered π-π interactions with the LM-PAEK matrix and the nucleation density of CF in the matrix. The crystallization behavior and interfacial properties of the CF/LM-PAEK composites were thoroughly investigated, revealing a distinct transcrystalline (TC) layer and improved interfacial shear strength and interlaminar shear strength due to the synergistic effects of electrochemical oxidation and controlled rate. The study highlights the importance of cooling rate and crystallization behavior in determining the crystallinity, spherulite size, and ultimately, the mechanical properties across diverse matrix composites. The findings provide valuable insights into the role of interfacial bonding strength and matrix ductility in high-performance LM-PAEK composites, offering a pathway to optimize the processing conditions for advanced composites.