The kinetic and thermodynamic analyses of non-isothermal degradation process of acrylonitrile–butadiene and ethylene–propylene–diene rubbers

The non-isothermal degradation processes of acrylonitrile–butadiene and ethylene–propylene–ethylidenenorbornene rubber compounds were investigated with thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG), using the different calculation procedures. It was found that the acrylonitrile–butadiene (NBR) and the ethylene–propylene–diene (EPDM) rubbers degradations represent the complex processes, where there are conversion regions with a constant value of the apparent activation energy (Ea). It was established that NBR and EPDM degradation under nitrogen atmosphere can be described by the one and a half order (n = 3/2) and the first order (n = 1) reaction kinetics, respectively. A linear dependence was observed between lnA and Ea, known as the kinetic compensation effect (KCE). The linear dependence was also established between the change of the entropy ΔS≠ and Ea, for the formation of the activated complex from the reagents. These dependences are related to assumption that the kinetic mechanisms of the non-isothermal degradation of the NBR and EPDM samples are very similar.