5000 h Multi-Factor Accelerated Aging Test of FRP Made Transmission Tower: Characterization, Thermal Decomposition and Reaction Kinetics Study.

Three kinds of fiber reinforced plastic (FRP) composites, including modified polyurethane resin (LGD), epoxy resin (E44) and modified unsaturated polyester resin (D33) glass-fiber reinforced plastics, were subjected to a 5000 h multi-factor accelerated aging test according to the power industry standard. To examine aging resistance and thermal stability of transmission towers made by these three composites, relevant bending properties, thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG), activation energy, as well as microscopic morphology were revealed. The results showed that for these composites, bending modulus retention rates were higher than 94% under the aging test and that of the LGD was highest. Additionally, the onset degradation temperature, temperature at maximum rate of weight loss and T(5%) reduced at 5000 h, with D33 having highest value and lowest decline rate. The activation energy was calculated with the Bagchi, Coats-Redfern and Broido method, respectively. Although the activation energy of all composites decreased after test, the D33, LGD materials had the highest activation energy which enjoys slight decline. Analysis of the whole experimental results suggested that D33 and LGD composites have good aging resistance, whose basic performance could still perform well after 5000 h aging test, so they can be used to composite towers and applied to engineering practice.