Investigation of Mechanical Properties and Oil Resistance of Hydrogenated-Butadiene-Acrylonitrile-Rubber-Based Composites Across Various Temperatures.

The influence of molecular structure (acrylonitrile content) and formulation (carbon black and plasticizer dosage) on the rheological and mechanical properties of HNBR composites was systematically studied, with further discussion on ozone resistance and swelling behavior in transformer oil. The results demonstrated that the curing characteristics and rheological behavior of HNBR composites are closely linked to acrylonitrile content, carbon black, and plasticizer levels. Plasticizers significantly reduced the degree of crosslinking and the Payne effect, while fillers had the opposite impact. Fillers increased the modulus at 100% and 200%, reducing elongation at break, whereas plasticizers enhanced elongation at break while lowering the modulus. The effects of fillers and plasticizers on tensile strength were relatively minor. Both exhibited different influences on mechanical properties at various aging temperatures. Compression set testing revealed that under a 125 °C hot air environment, the compression set was less than 30%, while at -30 °C in cold air, it exceeded 60%. In a 125 °C hot transformer oil environment, the compression set ranged between 30% and 60%. Oil resistance tests indicated that HNBR composites with higher acrylonitrile content showed lower mass change rates in transformer oil, with further reduction achieved by increasing the plasticizer or filler content. Due to their excellent performance and resistance to ozone cracking, HNBR composites have significant potential for applications in high-altitude power grids and military-grade rubber sealing products.