The improved interfacial property and solvent resistance of PEEK/GF composites by crystalline PEEK sizing agent

The sizing agents of glass fiber are usually epoxy and silane coupling agents, which can't withstand the processing molding temperature of PEEK resin matrix so the interfacial interaction of PEEK matrix and glass fiber is weak. In this work, PEEK polymers with disulfide bonds, which could be converted PEEK structure in mild condition, were synthesized and used as sizing agent of glass fiber to improve the interfacial properties of the glass fiber reinforced poly ether ether ketone (PEEK/GF) composites. The results showed that the interlaminar shear strength increased from 50.96 MPa of unsized GF reinforced PEEK composites (PEEK/UGF) to 93.22 MPa of sized GF reinforced PEEK composites (PEEK/SGF), with an increase of 82.93 %; Due to the improved interfacial properties of the PEEK matrix and GF, the bending strength and modulus of the PEEK/GF composite were increased from 701.30 MPa to 40.34 GPa for PEEK/UGF to 1398.40 MPa and 50.33 GPa for PEEK/SGF, an increase of 99.02 % and 24.76 %, respectively. The mechanism of interfacial enhancement was discussed through the analysis of cross-section morphology. In addition, PEEK sizing agent also had good solvent resistance, which hindered the erosion of organic solvents and the performance retention rate of the composite's ILSS remained above 80 % after PEEK/SGF composites were treated in high temperature organic solvents.