Multiscale enhancement behavior of nano‐silica modified CF/PEEK composites prepared by wet powder impregnation

The mechanical performance of modified multiscale carbon fiber (CF) reinforced poly(ether‐ether‐ketone) (PEEK) composites is improved through wet powder impregnation. The complex PEEK suspension is prepared by mixing nano‐silica and PEEK powders in water homogeneously. The CFs are pulled through the complex PEEK suspension, and the modified multiscale PEEK prepregs and composites are prepared by a series of drying and consolidation process. The increasing energy storage, decreasing tan δ max and the area under the tan δ curve in the dynamic mechanical tests indicate strong interface interactions of modified multiscale CF/PEEK composites. The interlaminar shear strength increases by 15.6% from 72.2 to 83.5 MPa for 2.5 wt% nano‐silica addition, showing significant improvement in resisting the delamination damage. Besides, the same addition makes the flexural strength and modulus increase by 13.9 and 8.6%, respectively. The modified multiscale CF/PEEK composites exhibit higher flexural strength and modulus at elevated temperature than the pristine composites. Furthermore, the enhancement mechanisms for the modified multiscale CF/PEEK composites are proposed and illustrated, which contributes to future research on multiscale enhancement for conventional composites. POLYM. COMPOS., 40:1187–1197, 2019. © 2018 Society of Plastics Engineers