New stabilizers for polystyrene based on 2-N-salicylidene-5-(substituted)-1,3,4-thiadiazole compounds

The photostabilization of polystyrene (PS) films by 2-N-salicylidene-5-(substituted)-1,3,4-thiadiazole compounds was investigated. The PS films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PS with irradiation time were also tracked (using benzene as a solvent). The quantum yield of the chain scission (Φcs) of these complexes in PS films was evaluated and found to range between 3.31 × 10−6 and 7.89 × 10−6. Results obtained showed that the rate of photostabilization of PS in the presence of the additive follows the trend: SN>SC>SB>SI>SPSN>SC>SB>SI>SPAccording to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among UV absorption, peroxide decomposer and radical scavenger for photostabilizer additives mechanisms were suggested.