FT–IR spectroscopic study on the photo‐ and photooxidative degradation of nylons

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Abstract
The progress of photo‐ and photooxidative degradation of nylon films were studied by FT–IR spectroscopy. The gases evolved from the photolysis of various nylons and their model amides were also analyzed. The formation of double bonds, changes of crystallinity, and the effect of amino and carboxyl end groups has been studied and discussed. The band shapes of the IR spectra pertaining to the carbonyl groups formed by thermal oxidation or photooxidation were found to be very similar, suggesting that the two oxidation mechanisms might be similar. The broadness of these bands indicates that the carbonyl groups may belong to more than one species. The photodegradation of nylons containing purposely inserted carbonyl groups formed CHCH2 groups. Carbonyl groups formed during oxidation, and present either as keto groups or part of N‐acylamide units make nylons susceptible to degradation reactions entailing mainly a Norrish type II mechanism.