The mechanism of the inhibited oxidation of polyformaldehyde

Abstract

DESPITE the large number of reports that have recently been published on the mechanism of the thermooxidative degradation of polyformaldehyde (PFA) this problem has not yet been adequately dealt with. The first investigations [1, 2] in which the decomposition of PFA was studied resulted in a suggested ionic mechanism for the degradation. In the next papers [3, 4] the dual nature, i.e. ionic and radical, of the polymeric active centres of degradation is pointed out. Other authors [5, 6] analysing the products of thermooxidative degradation of PFA suggest a radical chain mechanism involving the formation of the active centres R and RO~; the same view is held in [7, 8]. I t was suggested that peroxide radicals are formed in the radiolysis of PFA [9]; moreover, peroxide radicals of PFA were also found during mechanical degradation [10]. However, in the thermooxidation of PFA the formation of peroxide radicals and polymeric peroxide has yet to be shown by experiment. Furthermore the mechanism of the action of antioxidants requires elucidation as it is not known whether the termination of kinetic chains during inhibited oxidation takes place according to the generally accepted scheme: