Increase of Wear Resistance of Frost-Resistant Rubbers Due to Reinforcement By Multi-Wall Carbon Nanotubes
The effect of multi-walled carbon nanotubes (CNT) on the tribological and mechanical properties of sealing rubbers developed for use in the cold Arctic climate was experimentally studied. Two types of frost-resistant rubber based on epichlorohydrin (EPCHG) and butadiene-acrylonitrile (BNKS) rubbers were selected as objects. Rubber nanocomposites (N) were prepared by mixing CNT with rubber in plasticorder Brabender and then vulcanizing in a mold. CNT were functionalized by oxygen. The static µ<sub>о</sub> and dynamic µ coefficients of sliding friction were determined on a tribometer according to the contact scheme rubber ring - steel disc (simulation of the end seal) at two values of volume temperature T : 23 and -25 °C in the range of normal pressures ( P ) 0,1 - 0,4 MPa and sliding velocity V = 0,1-100 mm/s. Comparative tests to assess the abrasive wear resistance (AW) of the obtained N were carried out at P = 0,4 MPa, V = 10 mm/s, and T = 23 °C. An increase of stress at 100 % ( f <sub>100</sub>), elongation ε<sub>r</sub> and tensile strength f<sub>r</sub> on 27 % under introduction of CNTS in small quantities (1 phr) in rubber samples based on EPCHG as well as increase of the coefficient of frost resistance under compression К at -25 °C by 6 % were shown. Meanwhile the introduction of CNT in samples of BNKS in an amount of 5 phr only slightly increases f <sub>100</sub>, ε<sub>r</sub>, and f<sub>r</sub>. This effect is largely due to the chemical affinity of functionalized nanotubes and EPCHG rubber containing oxygen in the main chain. No change of µ<sub>о</sub> of EPCHG and increase of µ with the increase of CNT concentration in the range of V 0,1-100 mm/s was demonstrated. Introducing of small concentrations (1-5 phr) of CNT in EPCHG results in twice increase of AW resistance, meanwhile AW resistance of samples of BNKS increases only slightly.