Stabilization of Poly(vinyl chloride) containing captopril tin complexes against degradation upon exposure to ultraviolet light

Poly(vinyl chloride) (PVC) is commonly used in many industrial applications. Ultraviolet (UV) radiation causes undesirable changes to PVC properties. Therefore, PVC should be protected from radiation to increase its lifetime for outdoor applications. Here, new organotin complexes containing captopril were synthesized for use as low-concentration additives to enhance PVC photostability. Reacting captopril with the appropriate organotin chloride or dibutyltin oxide gave the corresponding organotin complex in 63% to 89% yield. Captopril tin complexes (0.5 wt%) were added to PVC solution and thin films were produced. The films were irradiated with UV light for 300 hours. The formation of specific functional groups and reduction in weight and molecular weight were monitored during irradiation. In addition, the surface morphology was checked pre before and after irradiation. The results confirmed that undesirable changes in the PVC films occurred to a lower extent in the presence of captopril tin complexes. These additives function as UV absorbers, scavengers for hydrogen chloride, and decomposers for peroxide and coordinate well with the PVC chains. The triphenyltin complex was the best inhibitor of PVC photodegradation, which is likely due to its high aromatic content.