THE INITIATION OF POLYPROPYLENE OXIDATION

The rate of primary initiation of the oxidation of polypropylene (PP) containing catalytic centers from inclusion of transition metals was e valuated. The rate was determined from the retardation period of the o xidation reaction in the fracture spots of stressed PP films with an i nhibitor, when the retardation period was close to the value of durabi lity: the number of initiation centers was taken into account. For thi s purpose, the predicted durability of samples was calculated for the concentration of initiation centers characteristic of the polymer with out additives. Inhibited PP films with various complexing agent conten ts introduced into the polymer to deactivate the catalytic centers wer e studied. The rate of initiation was shown not to change in the prese nce of the complexing agent, while the number of centers changed. Comp arison of the oxidation kinetics, derived from the oxygen absorption b y using data from this study, showed that the macrokinetic parameters were dependent on the number of initiation centers. Thus, the kinetic regularities were shown to be related to the catalytic activity of ini tiation centers and also to their concentration. (C) 1997 Elsevier Sci ence Limited.