Unlubricated rolling wear of HNBR/FKM/MWCNT compounds against steel

Abstract

AbstractThe rolling friction and wear of the compounds of peroxide‐cured hydrogenated acrylonitrile/butadiene rubber (HNBR) and fluororubber (FKM) (HNBR‐FKM) with and without multiwalled carbon nanotube (MWCNT) contents were studied against steel in orbital rolling ball (steel)‐on‐plate (rubber) test rig (Orbital‐RBOP). The phase structure of the rubber compounds in the presence and absence of MWCNT was studied by dynamic mechanical thermal analysis (DMTA), transmission electron and atomic force microscopy (TEM and AFM, respectively). It was established that HNBR formed the matrix in which micron‐scaled FKM domains were dispersed. MWCNT was preferentially embedded in the HNBR. The network‐related and surface tension properties of the rubber compounds were derived from DMTA tests and contact angle measurements, respectively. The Martens hardness of the rubbers was also measured. The coefficient of friction (COF) and specific wear rate (Ws) were determined in Orbital‐RBOP. Blending of HNBR with FKM increased the COF slightly and decreased the specific wear rate prominently when compared with pure HNBR. Additional MWCNT reinforcement (10 parts per hundred part rubber, phr) of the HNBR and HNBR‐FKM further increased the COF and at the same time improved the wear resistance. The wear mechanisms were concluded by inspecting the worn surfaces in scanning electron microscope (SEM) and discussed as a function of FKM and MWCNT modifications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009