Kinetic analysis of the thermal degradation of PP-EPDM blends

The thermal degradation of polypropylene (PP)/ethylene-propylene-diene rubb er (EPDM) and their blends is presented. In order to evaluate the effect of the components on the thermal stability, the degradation kinetics of blend s of different composition is analyzed by thermogravimetry in isothermal an d constant heating rate conditions in pure nitrogen. The Flynn and Wall met hod 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(alpha) function which is similar to an autocatalyti c type equation. Model parameters such as activation energies and pseudo or der of reaction are calculated using a non-linear regression analysis. Alth ough PP-EPDM blends are not compatible, the degradation process was not cle arly characterized by two independent reactions, suggesting that both compo nents are interacting during degradation. Moreover, the kinetic study showe d that the activation energy of the whole degradation process changes linea rly with the relative amount of the components; on the other hand, small di fferences were observed in the reaction orders.