Interface strengthening for carbon fiber-reinforced poly(ether-ether-ketone) laminated composites by introducing fluorene-containing branched poly(aryl-ether-ketone)

Fluorene-containing branched poly(aryl-ether-ketone) (BFPAEK) with terminal hydroxyl groups is synthesized by random copolycondensation reaction; then, the CF@BFPAEK/PEEK laminated composite is prepared by the “powder impregnation-high temperature compression molding” method with poly(ether-ether-ketone) (PEEK) as the matrix and BFPAEK-modified carbon fiber (CF@BFPAEK) as the reinforcement. When the content of branched units in BFPAEK is 10% and the coating amount of BFPAEK on the carbon fiber (CF) surface is 3 wt%, the CF@BFPAEK/PEEK laminated composite has outstanding mechanical properties, with an interlaminar shear strength (ILSS) of 57.3 MPa and flexural strength of 589.4 MPa, which are 80.2% and 44.3% higher than those of the pure CF/PEEK laminated composite (31.8 and 408.4 MPa), respectively. After 288 h of hydrothermal aging and high/low-temperature alternating aging, the corresponding retention rate of ILSS and flexural strength are respectively 87.9% and 84.7%, higher than those of pure CF/PEEK laminated composites (74.5% and 70.4%). The thermal conductivity coefficient and temperature for 5% weight loss of CF@BFPAEK/PEEK laminated composite are 1.85 W m⁻¹ K⁻¹ and 538.0°C, respectively.