Effect of thermal-oxidative aging on carbon fibre-bismaleimide composites

Purpose - The purpose of this paper is to investigate the effect of thermal-oxidative aging at 150 degrees C on the mechanical properties of carbon fibre reinforced bismaleimide composites. Design/methodology/approach - Composites specimens after thermo-oxidative aging at 150 degrees C for various times (up to 1,000 h) were investigated by scanning electron microscopy (SEM) for fracture morphology, Fourier transform infrared (FTIR) spectroscopy for chemical structures, and flexural strength test and inter-laminar shear strength (ILSS) test for mechanical properties. Findings - The results indicated that the mechanical properties of carbon fibre/BMI composites were affected significantly by testing temperature rather than by aging time. SEM results showed that the good adhesion of fibre and matrix resulted in the better mechanical properties. The composites showed lower flexural strength and ILSS at 150 degrees C due to the viscoelastic behaviour of matrix resin. The FTIR spectra confirmed the decomposition of crosslinked maleimide occurred just on the surface of composites during various aging times. Research limitations/implications - Results indicated that carbon fibre/BMI composites had excellent heat resistance and aging resistance. Practical implications - Due to their excellent thermal and mechanical properties, the carbon fibre/BMI composites show greater potential for their applications in some extreme fields such as aerospace and machine. Originality/value - The paper investigates the relationships of the fracture morphologies of composites and chemical structures of matrix resin to the mechanical properties after thermo-oxidative aging.