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

Emad Yousif,Ayad Hameed,Bashar Mudhaffar Abdullah,Nadia Salih,Jumat Salimon

doi:10.1186/2193-1801-2-104

Emad Yousif, Ayad Hameed + Show 3 more

Open Access

https://doi.org/10.1186/2193-1801-2-104

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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.

Highlights

Polystyrene is one of the important commercial polymers, widely used in various industrial fields
2,3-dihydro-(5-mercapto-1,3,4-oxadiazol-2-yl)-phenyl-2(substituted)-1,3,4-oxazepine- 4,7-dione compounds have been used as additives for the photo stabilization of PS films
Since the growth of carbonyl index with irradiation time is lower than PS control, as seen in Figure 1, it is suitable to conclude that these additives might be considered as photostabilizers of PS polymer

Summary

Introduction

Polystyrene is one of the important commercial polymers, widely used in various industrial fields. Results and discussion 2,3-dihydro-(5-mercapto-1,3,4-oxadiazol-2-yl)-phenyl-2(substituted)-1,3,4-oxazepine- 4,7-dione compounds have been used as additives for the photo stabilization of PS films. The absorption of the carbonyl and hydroxyl groups was used to follow the extent of polymer degradation during irradiation. A probable mechanism illustrating the experimental finding can be represented as follows (Safy & El-Laithy, 1994) (Scheme 1): in Figure 1, the Ico of IV, III, II, and I showed lower growth rate with irradiation time with respect to the PS control film without additives.

Results

Conclusion