Simulation of Thermal Behavior of Glass Fiber/Phenolic Composites Exposed to Heat Flux on One Side

Pyrolysis Kinetics Analysis and Prediction for Carbon Fiber-Reinforced Epoxy Composites

Carbon fiber-reinforced epoxy resin composites have poor high temperature resistance and are prone to thermal damage during service in the aerospace field. The purpose of this study was to evaluate the thermal decomposition (pyrolysis) characteristics of carbon fiber-reinforced epoxy composites and reasonably predict their thermal decomposition under arbitrary temperature conditions. The kinetic analysis was conducted on the thermal decomposition of carbon fiber-reinforced epoxy resin composites (USN15000/9A16/RC33, supplied by Weihai GuangWei Composites Co., Ltd. Weihai City, Shandong Province, China) under a nitrogen environment, and an improved model of pyrolysis prediction suitable for the arbitrary temperature program was developed in this work. The results showed that the carbon fiber-reinforced epoxy composites begin to degrade at about 500 K, and the peak value of the weight loss rate at the respective heating rate appears in the range of 650 K to 750 K. A single-step reaction can characterize the thermal decomposition of carbon fiber-reinforced epoxy composites in a nitrogen atmosphere, and a wide variety of isoconversional approaches can be used for the calculation of the kinetic parameters. The proposed model of pyrolysis prediction can avoid numerous limitations of temperature integration, and it shows good prediction accuracy by reducing the temperature rise between sampling points. This study provides a reference for the kinetic analysis and pyrolysis prediction of carbon fiber-reinforced epoxy composites.

Mechanism Identification and Kinetics Analysis of Thermal Degradation for Carbon Fiber/Epoxy Resin

For carbon fiber epoxy resin used in aerostructure, thermal degradation mechanism and kinetics play an important role in the evaluation of thermal response and combustion characteristics. However, the thermal decomposition process and mechanism are difficult to unify strictly due to the complexity of the components from different suppliers. In the present study, a product of carbon fiber epoxy resin made by AVIC (Aviation Industry Corporation of China) composite corporation is examined to identify its thermal degradation mechanism and pyrolysis products by measurements, including simultaneous thermal analysis, Fourier transform infrared spectroscopy and mass spectrometry, establish the kinetic model by Kissinger/Friedman/Ozawa/Coats-Redfern methods. The results show thermal degradation occurs in three steps under the inert atmosphere, but in four steps under air atmosphere, respectively. The first two steps in both environments are almost the same, including drying, carbon dioxide escape and decomposition of the epoxy resin. In the third step of inert atmosphere, phenol is formed, methane decreases, carbon monoxide basically disappears and carbon dioxide production increases. However, in air, thermal oxidation of the carbonaceous residues and intermolecular carbonization are observed. Furthermore, thermal degradation reaction mechanism submits to the F₄ model. These results provide fundamental and comprehensive support for the application of carbon fiber epoxy resin in aircraft industry.