Tribological behavior of a carbon-nanofiber-modified santoprene thermoplastic elastomer under dry sliding and fretting conditions against steel

Vapor-grown carbon nanofiber (CNF) was incorporated in concentrations of 0.9 and 4.5 wt % into a thermoplastic dynamic vulcanizate (TPV), Santoprene 8201-80HT, by melt blending. CNF was introduced from its aqueous dispersion with crumb ethylene /propylene / diene rubber as the carrier. The dispersion of the CNF was studied with transmission electron microscopy. The TPV compounds were characterized by dynamic mechanical thermal analysis, hardness measurements, and tensile and tear tests. For their tribotesting, different test configurations (pin on plate and roller on plate, where the plate was always the rubber) were adopted. The oscillation wear (fretting) of the CNF-modified TPVs was also studied. The coefficient of friction and specific wear rate of the TPVs were determined for each tribotest. These friction and wear parameters strongly depended on the tribotests' configurations. With increasing CNF content, the coefficient of friction and wear rate decreased for the pin-on-plate configuration. On the other hand, no such clear tendency could be deduced for the roller-on-plate configuration and fretting. The worn surfaces of the specimens were inspected with scanning electron microscopy, and the related mechanisms were discussed. (c) 2008 Wiley Periodicals, Inc.