Environmental aging performance and mechanism of T700 carbon fiber reinforced epoxy resin matrix composites

In order to verify the durability of composites, the microscopic morphology, surface element content, thermal properties and mechanical properties of T700 carbon fiber reinforced epoxy resin matrix composites were studied after environmental aging. The results show that the coaction of photo-oxidative degradation and thermo-oxidative degradation cause the T700 carbon fiber reinforced EP-A epoxy resin matrix (T700/EP-A) composites surface resin aging degradation. With the extension of environmental aging time, the glass transition temperature of T700/EP-A composites decreases gradually. After 3 years of environmental aging treatment, glass transition temperature of T700/EP-A composites decreases from 207℃(un-aged specimen) to 180℃, and to 172℃ after extending environmental aging of 5 years. Enhancing effects and damaging effects of the environmental aging process may coexist in the mechanical properties of the composites, thus resulting in different mechanical properties of T700/EP-A and T700/EP-B composites showing disparate trends. With the extension of environmental aging time, the longitudinal tensile strength of T700/EP-A and T700/EP-B composites first increases then decreases, the longitudinal flexural strength gradually increases, fluctuant longitudinal compress strength and interlaminar shear strength show no significant variation tendency.