process that involving several reactions that proceed in oxygen and without it. Thermal oxidation research of NBR has been carried out for decades. In the previous works [16e20], the effects of thermo- oxidation on the physical properties of NBR were investigated, and the volatile components and oxidative degradation products changes during thermal aging of NBR were analyzed. During the thermal aging, mainly three changes occurred successively: (1) migration and loss of additives such as plasticizers, stabilizers; (2) extra crosslinking of the rubber network; and (3) oxidation of macromolecular chains [21,22]. Although there are many studies [16e20,23e24] on the accelerated thermal aging behavior of NBR rubber up to now, the thermal aging mechanism of nitrile- butadiene rubber (NBR) still need to be studied further.