Enhancement of Photostabilization of Poly(vinyl chloride) Doped with Sulfadiazine Tin Complexes

New sulfadiazine tin complexes were synthesized in 67–80% yields from the reaction of sulfadiazine, and different organotin(IV) chlorides and their structures were established. The synthesized complexes were used as additives at a low concentration (0.5% by weight) to enhance poly(vinyl chloride) (PVC) photostability. The PVC samples containing sulfadiazine tin complexes (thickness = 40 μm) were fabricated and irradiated with ultraviolet light at room temperature for 300 h. The changes that occurred within the PVC samples upon irradiation were investigated by inspecting the loss in weight, reduction in the average molecular weight, formation of small degradation fragments containing polyene, carbonyl, and hydroxyl moieties, and changes in the ultraviolet absorption intensity of polymeric materials. The surface morphology of irradiated PVC samples was investigated using optical, atomic force, and scanning electron microscopies. There were lesser changes within the PVC samples with sulfadiazine tin complexes compared to the blank PVC sample. The dimethyltin(IV) complex was found to be the most efficient additive in stabilizing PVC against irradiation. The role played by the complexes in reducing the photodegradation of PVC was investigated, and a mechanism was proposed. J. VINYL ADDIT. TECHNOL., 26:370–379, 2020. © 2019 Society of Plastics Engineers