THERMOOXIDATIVE DEGRADATION OF NITRILE-BUTADIENE RUBBER

Results are presented on: (a) the nonisothermal degradation of nitrile-butadiene rubber (NBR) from TG, DTG and DTA data; (b) the accelerated isothermal thermal degradation of NBR at 80-degrees, 90-degrees and 105-degrees from the change in weight versus time data; (c) the accelerated isothermal thermal degradation of NBR at 80-degrees, 90-degrees and 105-degrees from the change in relative elongation at break with time. The thermal analysis data showed that the following processes occur successively during the nonisothermal heating of NBR in air: (1) the volatilization of the plasticizer and other ingredients; (2) the exothermic absorption of oxygen to yield nonvolatile oxidation products; (3) the decomposition of these products or their further interaction with oxygen to form volatile products. The results obtained from the three kinds of measurements were correlated to give a realistic picture of the processes responsible for the changes in the mechanical properties of the material as a consequence of its heating.