Properties of Carboxylated Nitrile Rubber/Hydrotalcite Composites Containing Imidazolium Ionic Liquids



In the present study, two types imidazolium salts containing the common cation 1-butyl-3-methylimidazolium-hydrophilic tetrachloroaluminate (BMIM AlCl4) and hydrophobic bis(trifluoromethylsulfonyl)imide (BMIM TFSI) are analyzed for effects on the ionic conductivity and the state of cure of carboxylated nitrile rubber/hydrotalcite composites (XNBR/HT). Imidazolium salt containing tetrachloroaluminate ions effectively participates in the crosslinking process of carboxylated nitrile rubber and contributes to an increase in the crosslink density of the composites. Hydrophobic 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was found to be compatible with carboxylated nitrile rubber. In the presence of 15 parts per hundred rubber (phr) of BMIM TFSI, the ionic conductivity of the composites increases from 10−10 to 10−7 S·cm−1, and the glass transition temperature (Tg) of the XNBR shifts towards lower temperatures from -23 °C to -33 °C.