β Scribed by Pross, A. W. ;Black, R. M.
No coin nor oath required. For personal study only.
Polythene of molecular weight 11,000 to 22,000 on exposure to bright sunlight undergoes deterioration resulting in embrittlement and degradation of electrical and mechanical properties. Deterioration is thought to be due to photocatalysed oxidation and this per describes a study of deterioration by artificial ageing. Curves relating power factor to oxygen absorption arc shown. The ultraβviolet absorption spectrum shows that the attack is probably due to the presence of carbonyl groups as an impurity in the polythene.
The effect of antioxidant addition was followed by folding endurance tests. Infraβred absorption spectra between 2.5ΞΌ. and 15ΞΌ. have been mapped before and after irradiation and the presence of hydroxyl, carbonyl and carboxyl groups established. The photochemical mechanism has been discussed and it is thought that the carbonyl groups are responsible for initiating the deterioration.
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The oxidative transformation of dichlorobenzenes photocatalysed by ZnO in aqueous solution has been studied using high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Many photoproducts were detected and their formation was quantitatively evaluated. With 1,