Thermal oxidation of ester-modified isotactic polypropylene

The relationship between the thermal oxidation of isotactic PP samples modified by esters miscible and immiscible with the polymer and the structure of these samples has been studied. An analysis of kinetic features of oxygen uptake, buildup of oxidation products, and changes in the mechanical properties and structural parameters of PP in the course of oxidation has shown that the effect of a modifier on the kinetics of thermal oxidation of the polymer depends on compatibility of an additive and a polymer matrix. The addition of ester that is partially miscible with PP accelerates oxidation. In the case of an immiscible ester, the effect is quite the reverse. This phenomenon is rationalized by the fact that the phase state of the system determines changes in the initial structure of the polymer matrix and, hence, manifestation of structural effects in the reaction kinetics and the participation of additives in chain reactions of cooxidation with PP.