Effects of Average Molecular Weight and Concentration of Polymer Additive on Friction and Wear

Abstract

Tribologzcal belzavior with oils containing PMAs differing inaverage molecular weight, Mw, is examined in sliding concentmted -cont~~c1S. At low loccds, low PMA Mw or higher concentrations of PMA have a beneficial effect on wear, but at high loads are detrimental. The beneficial effect is attributed to EHD film formation. The most important parameter is the number of PMA molecules per unit oil volzcme. The prowear action can be explained by the fkct that PMA molecules may accumulate in the inlet region of the contact. T l~e polymer accumuk~tion may block the bme oil entering the contact leuding to oil staruation which in turn leads to severe contacLq and incre~.~e.~ in wear. This a n a m l o w behavior may result from the competition between the prowear action and oil film formation.

Friction reduction in rolling bearing by using polymer additives

“…The reason for the decrease in lubricating effectiveness above this concentration could be attributed to temporary and permanent viscosity loss, 12 but it is impossible to explain the power action only considering this hypothesis.…”