Degradation Behaviors and Mechanism of Nitrile Butadiene Rubber Caused by Insulating Medium C5F10O.

C5F10O 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 C5F10O are studied. The influence of C5F10O/N2 mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C5F10O 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 C5F10O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO3. This consequently reduces the compression modulus of NBR. The interaction is related to CF3 radicals formed by the primary decomposition of C5F10O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF3 on NBR's backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters.

Ti3C2Tx as a Sensor for SF6/N2 Nitrogen-Containing Fault Decomposition Characteristic Products: A Theoretical Study.

The SF6/N2 gas mixture is an alternative gas to SF6. SF6/N2 will decompose and generate nitrogenous characteristic gases, such as NO, NO2, N2O, and NF3, when exposed to long-term partial discharge. The adsorption models of Ti3C2Tx (T=O, F, OH) and NO, NO2, N2O, NF3 were constructed, and the most stable adsorption structure was selected in this paper. The electron density and density of states of the adsorption system were further analyzed to study the adsorption behavior, and the sensing performance was evaluated in the end. The results are as follows: four gases could be spontaneously adsorbed on Ti3C2Tx, and strong adsorption occurred when surface terminal groups were OH, forming hydrogen or chemical bonds with significant charge transfer. Results show that Ti3C2(OH)2 had a stronger sensing ability than Ti3C2F2 and Ti3C2O2. The conductivity of the Ti3C2Tx with different terminal groups was improved after the adsorption of NO and NO2, showing Ti3C2Tx had a good sensing ability for NO and NO2. It was difficult for the four gases to desorb from the Ti3C2(OH)2 surface, but the adsorption on the Ti3C2F2, Ti3C2O2 surface had a short recovery time at room temperature.