Kinetic analysis of the thermal degradation of PP-EPDM blends

摘要

The thermal degradation of polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) and their blends is presented. In order to evaluate the effect of the components on the thermal stability, the degradation kinetics of blends of different composition is analyzed by thermogravimetry in isothermal and constant heating rate conditions in pure nitrogen. The Flynn and Wall method is used to obtain the activation energies from the dynamic tests, while isothermal test results are used to determine the pseudo order of reaction and the shape of the f(α) function which is similar to an autocatalytic type equation. Model parameters such as activation energies and pseudo order of reaction are calculated using a non-linear regression analysis. Although PP-EPDM blends are not compatible, the degradation process was not clearly characterized by two independent reactions, suggesting that both components are interacting during degradation. Moreover, the kinetic study showed that the activation energy of the whole degradation process changes linearly with the relative amount of the components: on the other hand small differences were observed in the reaction orders.