Rubber Composite Materials Based on a Bicontinuous Phase Design for Ultralow Temperature and Oil Resistance

ABSTRACT This research investigates the challenge of achieving both ultralow‐temperature tolerance and oil resistance in rubber systems for subsea and polar pipeline applications. In this methodology, a bicontinuous phase structure was designed for acrylonitrile‐butadiene rubber (NBR)/butadiene rubber (BR) composites. The blend ratios ranged from 60/40 to 70/30. Transmission electron microscopy (TEM) confirmed distinct bicontinuous structures in the 60/40 and 68/32 blends. In contrast, dynamic mechanical analysis (DMA) indicated good phase compatibility at most ratios, except for 63/37, where clear phase separation was detected. Key findings demonstrate that BR effectively improved low‐temperature flexibility, with brittleness temperatures reaching −60°C in the 60/40 composition compared with −30°C in pure NBR. Conversely, NBR contributed significantly to the increase in oil resistance. The abnormal swelling behavior of the 63/37 blend was attributed to interfacial defects. An optimal balance between low‐temperature resilience and oil resistance was achieved at ratios of 60/40 and 68/32, despite trade‐offs in tensile strength due to structural transitions. This work provides a viable strategy for developing high‐performance rubber composites for extreme environments.