Grey model prediction for the interfacial properties of carbon fiber-reinforced bismaleimide resin under thermo-oxidative aging

The overall performance of composites will be seriously affected when their interfacial properties degrade after thermo-oxidative aging (TOA). In this paper, the interfacial properties of carbon fiber (CF)/bismaleimide (BMI) resin aged for 10, 30, 90, 120 and 180 days at 200°C and 250°C were quantitatively studied by transverse fiber bundle tensile (TFBT) testing. In addition, a prediction model of interfacial strength based on the grey model theory was established. The results show that the interfacial strength for CF/BMI resin decreases exponentially with the extension of aging time, and the strength of the TFBT specimens aged at 200°C for 180 days and 250°C for 90 days decreases by 82.01% and 84.65%, respectively. This is caused by the oxidation decomposition of BMI resin and the mismatch of the thermal expansion coefficient between the CF and BMI resin. In addition, the grey model is used to predict the interfacial properties of CF-reinforced BMI resin under TOA. The prediction accuracy is higher than that of the traditional exponential model, and the prediction error is less than 10%. To sum up, this work can provide a reference for studying the evolution of interfacial properties of other kinds of fiber-reinforced polymer composites under extreme environments.