Multifunctional Role of Phenolic Novolac in NBR Vulcanizates: From Cure Kinetics to Thermal Degradation Inhibition

Nitrile butadiene rubber (NBR) possesses poor thermo‐oxidative stability, limiting its application at high temperatures despite its good chemical resistance in aggressive media. To eliminate this limitation, Novolac phenolic resin was incorporated into NBR as a thermal stabilizer. Thermal analysis revealed a 92.6% reduction in degradation enthalpy and a 5°C increase in onset degradation temperature at only 5 phr Novolac loading, indicating dramatically enhanced thermo‐oxidative resistance. The modified composites also retained acceptable tensile strength (13.8% loss) and elongation at break (23.5% loss), while dynamic mechanical analysis depicted improved viscoelastic characteristics. In addition, the composites exhibited excellent resistance to aggressive media, including acetone and permanganate solutions. These findings suggest that Novolac‐modified NBR is a promising candidate for petrochemical and aerospace applications with high‐performance requirements, where both thermal and chemical stability are required.