title: New photostabilizers for polystyrene based on 2,3-dihydro-(5-mercapto-1,3,4-oxadiazol-2-yl)-phenyl-2-(substituted)-1,3,4-oxazepine- 4,7-dione compounds.
abstract: The photostabilization of polystyrene (PS) films by 2,3-dihydro-(5-mercapto-1,3,4-oxadiazol-2-yl)-phenyl-2-(substituted)-1,3,4-oxazepine-4,7-dione compounds was investigated. PS films containing concentration of complexes 0.5% by weight were produced by the casting method from chloroform as a 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 (I > II > III > IV). According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive like UV absorption, peroxide decomposer and radical scavenger.
authors.affiliation: Department of Chemistry, College of Science, AL-Nahrain University, Baghdad, Iraq.
authors.forename: Emad
authors.initials: E
authors.lastname: Yousif
authors.forename: Ayad
authors.initials: A
authors.lastname: Hameed
authors.forename: Nadia
authors.initials: N
authors.lastname: Salih
authors.forename: Jumat
authors.initials: J
authors.lastname: Salimon
authors.forename: Bashar Mudhaffar
authors.initials: BM
authors.lastname: Abdullah
keywords: 1,3,4-oxadiazole; 1,3-Oxazepine; PS; Photochemistry; Photostabilizer; UV Absorber; UV–vis Spectroscopy
references.citation: J Photochem Photobiol B. 1998 Oct;46(1-3):96-103
references.pmid: 9894353