Triorganotin(IV) complexes photo-stabilizers for rigid PVC against photodegradation

The photostabilization of poly(vinyl chloride) (PVC) films by triorganotin(IV) complexes of the type Ph3SnL, Bu3SnL and Me3SnL of the benzamidoglycin complexes was investigated. The PVC films containing concentration of complexes 0.5% by weight were produced by casting method from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PVC films was evaluated and found to range between 5.91 × 10−8 and 7.67 × 10−8. Results obtained showed that the rate of photostabilization of PVC in the presence of the additive follows the trend:Ph3SnL > Bu3SnL > Me3SnLAccording to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them HCl scavenging, UV absorption, peroxide decomposer and radical scavenger for photostabilizer additives mechanisms were suggested.