Carbon fiber paper–reinforced thermoplastics (CPTs) are widely used because of their formability and superior mechanical properties. Polyamide 6 (PA6) is used as a resin matrix in carbon fiber-reinforced composites owing to its good mechanical properties and adhesion with the carbon fibers. However, PA6 tends to absorb moisture because of the presence of hydrophilic groups in the polymer backbone. This may negatively affect the mechanical and interfacial properties and reduce the service life of CPTs products. Therefore, this research focuses on the long-term applicability of CPTs in aqueous environments. In this study, CPT plates were fabricated by compression molding and subjected to long-term aging in a hydrothermal environment, and the effects of long-term aging on the properties of the composite were investigated. The water absorption behavior was found to follow Fick’s diffusion law, the interfacial property was determined by the microdroplet test, the surface morphology was analyzed by 3D laser scanning microscopy, the physicochemical properties were determined by differential scanning calorimetry and Fourier transform infrared spectroscopy, and the flexural properties were determined by the three-point bending test. A modified rule of mixture and the Kelly–Tyson model were applied to describe the changes in the flexural properties. The findings of this study provide guidance for the further application of CPTs products.

碳纤维纸增强热塑性塑料（CPT）因其可成型性和优异的机械性能而被广泛使用。聚酰胺 6 (PA6) 由于其良好的机械性能和与碳纤维的粘合性，被用作碳纤维增强复合材料中的树脂基体。然而，由于聚合物骨架中存在亲水基团，PA6 往往会吸收水分。这可能会对机械和界面性能产生负面影响，并降低 CPT 产品的使用寿命。因此，本研究侧重于 CPT 在水性环境中的长期适用性。在这项研究中，CPT 板通过压缩成型制造并在水热环境中进行长期老化，并研究了长期老化对复合材料性能的影响。吸水行为遵循菲克扩散定律，界面性质通过微滴测试确定，表面形貌通过3D激光扫描显微镜分析，理化性质通过差示扫描量热法和傅里叶变换红外光谱确定，弯曲性能由三点弯曲试验确定。应用修改后的混合规则和凯利-泰森模型来描述弯曲特性的变化。本研究结果为CPTs产品的进一步应用提供了指导。理化性能采用差示扫描量热法和傅里叶变换红外光谱法测定，弯曲性能采用三点弯曲试验测定。应用修改后的混合规则和凯利-泰森模型来描述弯曲特性的变化。本研究结果为CPTs产品的进一步应用提供了指导。理化性能采用差示扫描量热法和傅里叶变换红外光谱法测定，弯曲性能采用三点弯曲试验测定。应用修改后的混合规则和凯利-泰森模型来描述弯曲特性的变化。本研究结果为CPTs产品的进一步应用提供了指导。