The oxidative degradation of polyvinyl formal at temperatures of 150°C. and above has been followed by changes in the infrared spectrum in conjunction with the loss in weight and color development. It is a complex process of cross‐linking and oxidation, rather than one of depolymerization. The infrared spectrum shows rapid development of carbonyl and ethylenic groups in the molecule, accompanied by loss of carbon‐hydrogen and formal groups. A free radical mechanism for the rupture of the formal ring is proposed, which explains the loss of formaldehyde and water from the polymeric molecule and the production of carbonyl and ethylenic groups in the chain that are capable of producing color. The stability of polyvinyl formals of various compositions is compared and the effects of residual acetate and alcohol groups on the rate of degradation are discussed. Several catalysts and inhibitors for the process are also presented.
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Beachell et al. (1951) studied this question.
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