Degradation Behaviors and Mechanism of Nitrile Butadiene Rubber Caused by Insulating Medium C 5 F 10 O.

CFO is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to CFO are studied. The influence of CFO/N mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between CFO and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with CFO, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO. This consequently reduces the compression modulus of NBR. The interaction is related to CF radicals formed by the primary decomposition of CFO. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF on NBR's backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters.