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 µо 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 100), elongation εr and tensile strength fr 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 100, εr, and fr. This effect is largely due to the chemical affinity of functionalized nanotubes and EPCHG rubber containing oxygen in the main chain. No change of µо 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.