The influence of long carbon fiber and its orientation on the properties of three-dimensional needle-punched CF/PEEK composites

Abstract

In this work, high performance composite materials with high mechanical strength and isotropic properties are expected to obtained. Long carbon fiber (40 mm) reinforced poly(ether ether ketone) (PEEK) composites were prepared by three-dimensional (3D) needle-punched method. Orthogonal test was used to optimize molding parameters of 3D needle-punched CF/PEEK (30/70) composites. The influence of carbon fiber content and its orientation on the mechanical properties, thermal properties, crystallization properties and microstructure of the composites were studied in the range of 30–60 wt %. The excellent mechanical properties were shown with the increase of fiber content, and the composites were approximately isotropic in-plane due to the random fiber orientation. With the increase of carbon fiber content, the melting point measured by differential scanning calorimetry (DSC) and 5% weight loss temperature tested by thermogravimetric analysis (TGA) of the composites increased slightly, however the heat deflection temperature (HDT) increased obviously. SEM observation showed that compared with traditional thermoplastic plate, 3D needle-punched CF/PEEK composites could provide multi-direction impregnation channel for PEEK melt resin to realize multi-point impregnation, as a result, carbon fiber had a better impregnation effect in PEEK resin matrix. It was found that the tensile modulus and flexural modulus of CF/PEEK were very close to those of human cortical bone. It would reduce the stress shielding effect and has great application value if it is applied to the orthopaedic bone plate.