Study on Weather Aging of Nitrile Rubber Composites Containing Imidazolium Ionic Liquids

Abstract

SummaryWeather aging of nitrile rubber composites containing hydrophilic 1‐ethyl‐3‐methylimidazolium thiocyanate (EMIM SCN) and hydrophobic 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI), and 1‐allyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (AMIM TFSI) ionic liquids was investigated. The mechanical properties at small (dynamic mechanical analysis) and high deformation (tensile test), the hardness and the electrical properties were measured before and after the aging process. It was found that the presence of hydrophobic ionic liquids in the nitrile rubber enhanced the retention of their mechanical properties (tensile strength, stiffness) and slightly reduced surface defects (as determined by scanning electron microscopy), thereby retarding the aging of rubber composites. However, the presence of hydrophilic EMIM SCN in the composite accelerated the degradation of the studied materials because of its high crosslinking activity during the aging process. The electrical studies showed also lower stability of hydrophilic ionic liquid (EMIM SCN) in the studied nitrile matrix (leaking effects) compared to the hydrophobic one (EMIM TFSI, AMIM TFSI).