Ultraviolet resistance of azo-containing poly(1,3,4-oxadiazole) fibres

To improve the ultraviolet (UV) resistance of poly(1,3,4-oxadiazole) (POD) fibres, 4,4′-azodibenzoic acid (ADA) was introduced into the POD fibres through copolymerization and blending respectively. The influence of UV light on the intrinsic viscosity and mechanical properties of POD fibres with and without azo groups was investigated in detail. The results revealed that the tensile strength retention of the POD fibres containing ADA was much higher than that of the POD fibres without the azo groups (p-POD) after accelerated irradiation using an iodine-gallium lamp. It was also found that POD with ADA in the molecular chain (c-POD) by copolymerization showed better UV stability than that of the POD blended with the same amount of ADA (b-POD). The UV spectrum was used to explore the UV resistance mechanisms of the series of the POD containing azo groups and it was demonstrated that the mechanisms of b-POD and c-POD were different.