This study aims to disclose the thermo-oxidative degradation behaviors and kinetics of a carbon fiber reinforced polyimide (CFRPI) composite for modeling of the long-term degradation process. The degradation behaviors were revealed through off-gas products analysis, and the overall kinetic interpretation was achieved from study of the mass-loss curves recorded under dynamic conditions. It was found that thermo-oxidative degradation of the CFRPI composite was a multistep process, which included four main reaction steps. Since most kinetic analysis methods were derived from simple reactions described by a single kinetic triplet, they cannot be applied reliably to such a process. Therefore, we firstly separated the four overlapped reaction steps by peak fitting of derivative thermogravimetric curves using Frasier-Suzuki equation considering the asymmetrical nature of kinetic curves, and subsequently analyzed each individual reaction employing Friedman method and experimental master-plots method. Four sets of kinetic triplets were determined to characterize the entire degradation process. The validity of four corresponding kinetic triplets was confirmed by perfect simulation of mass-loss curves recorded at both dynamic conditions used in kinetic analysis and entirely different isothermal conditions. Finally, modeling of long-term aging at 400 °C of the CFRPI composite was successfully achieved based on these kinetic triplets. The predicted mass loss and flexural property correlated well with experimental results. This study can serve as a basis for rapid evaluation of the long-term durability of the CFRPI composite in various application environments.

这项研究旨在揭示碳纤维增强聚酰亚胺（CFRPI）复合材料的热氧化降解行为和动力学，以对长期降解过程进行建模。通过废气产物分析揭示了降解行为，并且通过研究在动态条件下记录的质量损失曲线获得了整体动力学解释。发现CFRPI复合材料的热氧化降解是一个多步骤过程，包括四个主要反应步骤。由于大多数动力学分析方法均源自单个动力学三重态描述的简单反应，因此无法可靠地应用于此类过程。因此，我们首先考虑动力学曲线的不对称性，使用Frasier-Suzuki方程通过导数热重曲线的峰拟合分离了四个重叠的反应步骤，然后分别使用Friedman方法和实验性主图方法分析了每个反应。确定了四组动力学三联体以表征整个降解过程。通过在动力学分析中使用的动态条件和完全不同的等温条件下记录的质量损失曲线的完美模拟，证实了四个相应的动力学三重态的有效性。最后，基于这些动力学三元组成功地实现了CFRPI复合材料在400°C下长期老化的建模。预测的质量损失和弯曲性能与实验结果很好地相关。