Hygrothermal aging behavior and flexural property of carbon fiber-reinforced polyethylene terephthalate glycol composites

Fiber-reinforced polymer matrix composites during engineering applications can be influenced by critical environmental conditions (e.g., water and temperature), probably causing a negative impact on the mechanical performance. In this work, the hygrothermal aging behavior and flexural property of carbon fiber (CF)-reinforced polyethylene terephthalate glycol (PETG) composites were investigated at different aging temperatures and days. The CF/PETG composites were fabricated using the hot-press molding method. The mathematical fitting model and finite element analysis method were employed to reveal the hygrothermal aging behavior and the moisture absorption evolution. After 90 days of aging, the water uptakes of the specimens at 25°C, 45°C, and 60°C are 0.55%, 0.62%, and 1.67% for PETG and 0.47%, 0.54%, and 1.52% for CF/PETG, respectively. The flexural strengths of the CF/PETG composites at 25°C, 45°C, and 60°C after 90 days of aging decrease by 28.6%, 30.2%, and 32.2% as compared with the non-aging composites, respectively. The water uptakes of the CF/PETG composites tend to increase with the increase in cyclic aging time interval. The flexural strengths of the composites with the cyclic aging intervals of 2, 5, 10, and 15 days first decrease and then increase slightly. The knowledge gained in this study will benefit future design optimization of the CF/PETG composite material and lay the foundation for its engineering application.