Thermal‐oxidative aging effects on the properties of long glass fiber reinforced polyamide 10T composites

The results of thermal‐oxidative aging effects on the properties of long glass fiber reinforced polyamide 10T (LGF/PA10T) composites were investigated. The composite samples were aged at 240°C in a heat‐blast oven. The aging times were 10, 20, 30, 40, and 50 days. The thermal‐oxidative aging resulted in decline of crystallization behavior, dynamic and static mechanical properties of the LGF/PA10T composites. These observations can be attributed to the decomposition of the molecular chain of PA10T resin, carbonization of the matrix and interfacial debonding between the glass fibers and matrix, as illustrated by scanning electron microscopy and FTIR spectra. At the initial stage of aging, the storage modulus and glass transition temperature first increased and then reduced, which indicated that there was slight crosslinking between the molecular chains. After aging for 50 days, the retention rates of tensile strength, flexural strength, and notch impact strength of the composite samples were 4.9, 6.3, and 9.4% lower, respectively, than that of the unaged samples; thus, it can be concluded that molecular degradation dominated and caused deterioration of interfacial adhesive strength between the fiber and the resin during the whole aging process. Therefore, the LGF/PA10T resin cannot serve for a long‐time at 240°C. POLYM. COMPOS., 39:2117–2125, 2018. © 2016 Society of Plastics Engineers