Aging performance investigation and improvement of modified polyurethane composites for composite overhead transmission line towers

•A 5000 h multi-factor accelerated aging test was carried out.•The aging performance of modified polyurethane composites for transmission line towers with different processes were investigated.•The influence of ultraviolet absorber and ultraviolet stabilizer on polyurethane composites was studied.•An aging performance improvement scheme of polyurethane composites was proposed. Fiber reinforced plastic has the characteristics of light weight, high strength, good aging performance and strong insulation performance, so the composite overhead transmission line tower may become a substitute for the traditional iron tower in the future. At present, the researches on the composite transmission tower mainly focused on the electrical properties, few on the aging performance, which is an unknown influence on the transmission line with composite transmission towers. In this paper, a 5000 h multi-factor accelerated aging test was used to investigate the aging performance of modified polyurethane (PU) composites for composite transmission towers. The test periodically simulated the environment of high voltage, rainfall, humidity, alternating high and low temperatures, ultraviolet and salt fog. The results show that pultrusion process PU composites are more suitable to be used as the materials of composite towers because of its higher bending modulus. Then, a research on PU composites aging performance improvement scheme was carried out by another multi-factor accelerated aging test. The results show that the mixture of ultraviolet absorber and ultraviolet stabilizer is helpful to improve the aging performance of PU composites, and the addition of 0.275wt% of the total amount with a ratio of 1:1 is a viable scheme.