Investigation of the properties and aging mechanisms of vulcanized hydrogenated nitrile rubber in different mediums

Abstract

AbstractPacker rubber cylinders in oil drilling operations must withstand high pressure, high temperature, and destruction of mediums. To ensure the long‐term service time of the hydrogenated nitrile rubber (HNBR) packer rubber cylinders, it is essential to understand the aging mechanism of HNBR in different aging environments. Four HNBR with various acrylonitrile contents (ACN 17%, 21%, 34%, and 43%) were prepared in this work, and effect of CN content on the mechanical properties, aging resistance, and dynamic mechanical properties of HNBR were investigated respectively. It was observed that the higher the CN content, the stronger the mechanical properties of the HNBR, and the mechanical properties of HNBR with high CN content decayed rapidly at high temperatures. According to the thermo‐oxidative aging data, the cross‐linking reactions were investigated during the thermo‐oxidative aging of HNBR, leading to a decrease in the properties of HNBR. In a high temperature (180°C) aqueous medium, the chemical structure of HNBR underwent dramatic changes. The CN group is converted to CONH2 and COO− group, and the resulting COO− reacted further with CONH2 in deionized water and with metal ions (Ca2+ or Mg2+) in mineralized and oily water to form cross‐linking network, and the possible aging mechanisms of HNBR in different mediums were given.