Salt Spray Aging Behavior and Life Prediction of Thermoplastic Carbon Fiber-Reinforced Poly(methyl methacrylate)...

To investigate the salt spray durability of recyclable carbon fiber-reinforced poly(methyl methacrylate) (PMMA) composites (CF/PMMA), laminates were fabricated via vacuum-assisted resin transfer molding (VARTM), and salt spray accelerated aging tests were conducted. Water uptake tests, mechanical tests (0°/90° tensile, flexural, short-beam shear), and SEM micro-characterization of surface and fracture morphologies were performed to compare the performance degradation and interfacial deterioration of the two systems under salt spray conditions, and the residual strength was predicted using the median strength aging equation model. The results show that unaged CF/PMMA exhibits higher initial mechanical properties than carbon fiber-reinforced epoxy composites (CF/Epoxy) and lower equilibrium water uptake due to fewer polar groups in the salt spray aging process. After 960 h of aging, CF/PMMA retains better mechanical properties (retention rates: 68.19%, 78.94%, 84.03%, and 76.28% in 0° tensile, 90° tensile, flexural, and shear strengths, respectively) than CF/Epoxy. Based on the life prediction model, under the artificial accelerated salt spray aging test condition and with 50% strength retention as the failure threshold, the predicted tensile and shear service lives are 99.05 days and 389.06 days, respectively. This study elucidates the salt spray aging mechanism of PMMA-based thermoplastic carbon fiber composites, providing a reference for their marine engineering applications.