Durability Study of Carbon/Glass Hybrid Fiber Reinforced Polymer Tubes Under Hygrothermal Environments

Carbon/glass hybrid fiber reinforced polymer (C/GFRP) tubes, featuring a carbon fiber mat inner liner and an outer glass fiber winding structure, combine the high corrosion resistance of carbon fiber with the cost-effectiveness of glass fiber, demonstrating significant potential in pipeline engineering. This paper systematically investigated the hygrothermal durability of C/GFRP tubes through accelerated aging tests (25°C, 40°C, and 60°C distilled water environments for 30–146 days). Results indicate that water absorption in C/GFRP follows a two-stage diffusion model. After 146-day aging, the water absorption rates reached 0.257%, 0.386%, and 0.537% at 25°C, 40°C, and 60°C, respectively, with elevated temperatures significantly accelerating water absorption. Fiber-resin interface debonding occurred on both inner and outer surfaces under hygrothermal environments, leading to an 18.9% reduction in hoop tensile strength after 146 days at 60°C, while shear properties remain less affected. Hydrolysis and plasticization of the resin reduced the glass transition temperature (T_g) by 2.4%–11.6% after 146 days of aging, while microcrack formation prolonged ultrasonic guided wave signal reception time by 8.0 μs. Based on Arrhenius theory, the service life of C/GFRP tubes was predicted for scenarios where tensile strength degrades to 50% at 5.4°C, 12.9°C, and 17.8°C.