Changes in tribological performance of high molecular weight high density polyethylene induced by the addition of molybdenum disulphide particles

V PETTARÍN; CHURRUCA, M.J.; D. FELHÖS; J. KARGER-KOCSIS; P. FRONTINI

WEAR

ELSEVIER SCIENCE SA

Año: 2010 vol. 269 p. 31 - 45

0043-1648

Through this work, the effect of the addition of commercial molybdenum disulphide on the tribologicalbehavior of high molecular weight high density polyethylene was assessed. Determination of severaltribological parameters (kinetic coefficient of friction by sliding testing, static coefficient of friction byscratch testing, sliding wear rate by roller-on-plate test, abrasive wear rate by dry sand/rubber wheel test,and surface hardness by microhardness measurements) and microscopical observations (by TOM, SEMand EDAX) were combined in an attempt to elucidate the effect of MoS2 in composites performance. Inthis way, a complete picture of composites behavior was achieved. An content of MoS2 for minimum wearrate was encountered to be around 10 wt.%. It was found that the solid lubricant increases wear resistanceunder both sliding and abrasive wear conditions. It seems that depending on wear condition MoS2 actsin a different way. It appears that MoS2 contributes to dissipate the generated heat, thus decreasingwear due to surface melting of the polymer. Under sliding conditions, an adhesive wear mechanismbecame dominant which is characterized by the formation of a uniform and adherent transfer film on thecounterface. Under abrasive conditions a positive rolling effect of MoS2 particles was found. Amounts offiller larger than 10% resulted in a detriment of wear resistance due to weak microstructures which leadto the occurrence of micro-cracking wear mechanism. Besides, the effect of MoS2 particles upon HMWHDPEstress–strain and fracture behavior was checked for the composite with the best wear performance.Low strain mechanical properties ofHMW-HDPEremained almost unaltered while a noticeable change inhigh strain properties resulted from the introduction of filler. Fracture mode was also changed from stableto unstable under quasi-static conditions and from semi-ductile to brittle under dynamic conditions, witha concomitant abrupt reduction in toughness values.