Abstract
To meet the requirements of transformer rubber sealing materials for excellent mechanical properties and thermal stability, this study designed nitrile rubber (NBR)/acrylate rubber (ACM) blends with a dual vulcanization system, and systematically investigated the effects of different blend ratios on their comprehensive properties. The vulcanization characteristics, mechanical properties, thermal stability, oil resistance, and low-temperature sealing performance of the blends are significantly dependent on the NBR/ACM ratio. The optimal comprehensive performance is achieved when NBR:ACM = 90:10, which not only retains the good mechanical advantages of NBRtensile strength of 21.15 MPa, elongation at break of 276%, 100% modulus of 6.35 MPa, and initial hardness of 71 Shore Abut also inherits the excellent heat resistance of ACM. After 125 °C × 168 h hot air aging, its hardness increases by 7 Shore A, and the change rate of elongation at break is only 20.2%, which is much lower than the 56% of pure NBR. Studies on the compatibility with transformer oil and low-temperature sealing performance show that after aging in 125 °C transformer oil for 168 h, the blend with this ratio has a volume change rate of 2.8% and a mild increase in compression set, with the smallest impact on transformer oil performanceacid value increases by only 0.03 mg KOH/g and dielectric loss factor by 0.29%, close to the level of pure ACM. After high-temperature hot air aging and oil aging, its low-temperature nitrogen leakage point remains stable at around -20 °C, significantly better than the obvious increase of pure NBR. This ratio of blend can adapt to the complex sealing environment of transformers, and provides a practical solution for the material upgrade of transformer seals by reducing insulation oil pollution, delaying oil degradation, lowering maintenance costs, extending the service life of seals, and avoiding failure risks.