Effect of ionic liquids on tribological properties of water-iubricated nitrile rubber rubber

Abstract

Nitrile rubber(NBR)-based composites modified with three kinds of imidazolium-based ionic liquids were prepared by mechanical mixing method. Curing characteristics, dynamic mechanical properties, physical and mechanical properties and friction performance of composites under the water lubricating were studied. The tribological properties of the materials were compared with the test of friction coefficient, surface morphology and wear volume. The mechanism of three kinds of imidazolium-based ionic liquids was explored．The results showed that three kinds of imidazolium-based ionic liquids had a positive effect on the cross-linking density and physical and mechanical properties of NBR. The volume change rate of NBR with 1-butyl-3-methylimidazolium hexafluorophosphate[(BMim)PF6] declined apparently in deionized water. Three kinds of imidazolium-based ionic liquids reduced the linear velocity of NBR to mixed lubrication state from 0.180 m/s to 0.045 m/s. The linear velocity of NBR with 1-butyl-3-methylimidazolium bromide[(BMim)Br] and [(BMim)PF6] was 1.800 m/s to the elastohydrodynamic lubrication. The improvement effect of three kinds of imidazolium-based ionic liquids on friction coefficient was especially remarkable in the boundary lubrication stage and mixed lubrication stage. [(BMim)Br] and [(BMim)PF6] had better effect on improving dynamic friction. The static friction coefficient and volume wear of NBR with 1-butyl-3-methylimidazolium tetrafluoroborate [(BMim)BF4] and [(BMim)PF6] had more significant improvement.

Keywords

• nitrile rubber
• ionic liquid
• water lubrication
• friction performance
• curing characteristics
• physical and mechanical property