Abstract
A kinetic study of the oxidation of butadieneβstyrene and butadiene polymers in the presence of secondary aromatic amine inhibitors has been made over the temperature range 70β150Β°C. The rate of the inhibited oxidation has been found to depend upon the inhibitor concentration. In contrast with other inhibited processes, this relation is described by a curve with a minimum. The concentration corresponding to the latter depends upon the oxidation temperature, polymer reactivity, and lability of the imino hydrogen of the inhibitor molecule. Experimental data and kinetic computation have shown that the extreme on the efficiencyβconcentration curve is due to the fact that the amine not only exerts a retarding but also an initiating effect on the polymer oxidation process. The latter is due to direct interaction of the amine and molecular oxygen during the inhibited oxidation of the polymer. The kinetics of oxidation of the amine have been investigated. The duration of the induction period of the polymer oxidation process does not increase in proportion with the inhibitor concentration. The relation between the length of the induction period and rate of oxidation of the polymer for various inhibitor contents has been investigated and discussed. The inhibitor concentration exerts a marked influence on the overall rate of structural changes undergone by the polymer in the oxidation process and also on the ratio of the degradation and structuration velocities of the molecular chains. The change in efficiency of the inhibitor with respect to the oxidation temperature has been examined.