Preparation and Properties of M40 Carbon Fiber-Reinforced Thermoplastic Polyimide Composites

Abstract

A series of M40 high modulus carbon fiber-reinforced polyimide (CFRPI) composites are prepared by laminating premolding PI films with unidirectional CF layers. After the imidization processing of premolding PI films is estimated, the effect of CF volume fraction, processing conditions, and PI molecular structure on the properties of CFRPI composites is studied in detail. In addition, SiO2 nanoparticles are added as fillers to the premolding PI films at varying concentrations. The effect of the nanoparticles on the properties of CFRPI composites is also investigated. The surface characteristics of M40 CF are measured by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The thermal and mechanical properties of CFRPI composites are measured by dynamic mechanical thermal analysis, SANS testing machine, scanning electron microscopy, and other techniques. The experimental results show that the properties of CFRPI composites are mainly affected by the premolding PI film and molding conditions. The change of CF volume fraction from 55 to 65% has little effect on the mechanical properties of the CFRPI composites. In addition, flexible PI as a CF sizing improves the interlaminar shear strength, flexural strength, and flexural modulus of CFRPI composites, and the incorporation of SiO2 nanoparticles further improves the properties of CFRPI composites.