Surface wettability, tensile mechanical performance, and tribological behavior of polyimide/polytetrafluoroethylene blends enhanced with hydroxylated multiwalled carbon nanotubes at high relative humidity
Shicheng Yan, Yahong Xue
Abstract
Abstract Multiwalled carbon nanotubes were hydroxylated (MWCNTs‐OH) by a strong acid mixture and then used as a reinforcement nanofiller in blends of polytetrafluoroethylene (PTFE) and polyimide (PI) to fabricate MWCNTs‐OH/PTFE/PI nanocomposites. The influences of MWCNTs‐OH additions on the surface wettability, tensile mechanical property, and tribological behaviors of MWCNTs‐OH/PTFE/PI nanocomposites under different relative humidity were investigated. Test results indicate that the introduction of MWCNTs‐OH can dramatically decrease the static water contact angles and increase the tensile strengths and elastic moduli of the PTFE/PI polymer blends. This is largely due to the existence of numerous hydrophilic functional groups on the surfaces of MWCNTs‐OH and its ultrahigh mechanical characteristics. The relative humidity has a much weaker impact on the friction coefficients of the MWCNTs‐OH/PTFE/PI nanocomposites than on the wear rates. Of all composites, the 0.8 wt% MWCNTs‐OH/PTFE/PI nanocomposite possesses the lowest friction coefficient (0.11) and wear rate (2.97 × 10 −15 m 3 /(Nm)) at a high relative humidity of 90%. The conspicuous increase in wear resistance is attributable to the enhancement effect of MWCNTs‐OH and the generation of homogeneous polymer self‐lubricating tribofilms.