A process for the synthesis and use of highly aromatic organosilanes as additives for poly(vinyl chloride) films

Three organosilanes were synthesized in good yields from the condensation of 4,4′,4″- ((phenylsilanetriyl)tris(oxy))tribenzaldehyde and 4-substituted anilines under acidic conditions. The structure of the organosilanes was confirmed using a variety of techniques. Organosilanes were mixed with poly(vinyl chloride) (PVC) and homogenous films were produced. The effect of longterm irradiation on the films containing organosilanes was tested using various methods. Monitoring the infrared spectra of PVC films before, during and after irradiation processes showed the formation of side products comprising polyene, carbonyl and hydroxyl groups. The intensities of absorption bands due to these functional groups were much lower in the presence of organosilanes as compared to the blank film. Also, the decrease in the weight and molecular weight of PVC films after irradiation was lower in the presence of organosilanes. Additionally, there was a minimal surface change of irradiated PVC in the presence of organosilanes. Clearly, organosilanes act as inhibitors, particularly the one containing the hydroxyl group, for the photodegradation of PVC. Different mechanisms were proposed to speculate the role played by organosilanes in stabilizing PVC against long-term ultraviolet light exposure.