UV durability assessment of a thermoplastic epoxy-based hybrid composite rod for structural reinforcement and retrofitting

Recently, a hybrid composite cable has been developed for external strengthening of structures in seismically active zones, containing a novel thermoplastic epoxy matrix. While this resin has advantageous properties such as processability, the UV resistance for outdoor service conditions has not been studied. This paper examines the accelerated UV degradation behavior by using a xenon arc source, and reporting the changes in chemical structure and mechanical properties of both the resin and FRP rods. While the neat resin is susceptible to photo-oxidation and a sharp decline in strength, the hybrid FRP shows no significant changes in tensile properties even after nearly 2000 MJ/m2 of UV radiation (equivalent to seven years in Florida, USA). This was attributed to the fiber-dominant nature of unidirectional composites, further supported by a Curtin-type analytical model.