Electron and probe microscopy investigation of the surface of elastomers modified with antifriction fillers

Abstract

The surface of frost-resistant elastomers (rubbers) based on nitrile-butadiene rubber and propylene- oxide rubber (pure and modified with fillers: ultrafine PTFE and carbon black) is investigated. Tribological tests show that the addition of carbon black produced the greatest effect: the friction coefficient decreases to 0.2 and remains virtually constant during cooling. Surface and subsurface defects are detected by SEM. These defects can affect the processes in the zone of friction and destruction of the sliding surface of rubber. It is demonstrated that the modification of propylene-oxide rubber results in surface smoothing; the effect is the most pronounced in the samples modified with carbon black. The potential to use scanning probe microscopy for local investigation of the surface of rubber is assessed. A conclusion is made about the adhesive properties of surfaces based on the obtained force–distance curves. The investigation of vibration parameters of a probe in contact with the surface provides an opportunity to estimate the surface elasticity. It is shown that the addition of carbon black results in an increase in hardness of the rubber samples and a drastic reduction in adhesion. At the same time, the introduction of ultrafine PTFE leads to a slight enhancement of the adhesion and hardness. It is concluded that carbon black is the best modifying additive for the studied elastomers.