Abstract

The influence of introducing benzothiazole and benzimidazole as a pending groups into the repeating unit of PVC has
been studied on the bases of photostability measurements. The photostability of modified polymers were studied by
monitoring the carbonyl Index (ICO), polyene index (Ipo) and hydroxyl index (IOH), all results obtained indicated that
PAA, PSS, PNN, PSA and PNA gave lower growth rate of ICO, IPO and IOH with irradiation time with respect to
unmodified PVC film (control). The following trends of photostability are obtained
PAA>PSS>PNN>PSA>PNA
According to the experimental results several reaction mechanisms were proposed depending on the presence of
benzothiazole and benzimidazole moieties in the polymer chain. The mode of chain scission was also investigated by
measuring the variation of average viscosity molecular weight with irradiation time for modified PVC. The degree of
deterioration (?) and the average number of chain scission (S) values were also calculated.

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