Reduction of Friction by Functionalised Viscosity Index Improvers

Abstract

A range of functionalised polymethacrylate copolymers have been synthesised with different functionalities, polymer architecture and molecular weight. It is shown that appropriately functionalised block copolymers give enhanced film thickness and greatly reduced friction under low entrainment speed conditions, even with polymer concentration as low as 1% wt. This behaviour almost certainly results from the formation of an adsorbed brushlike film of thickness ca 20 nm on each polar surface. These films provide a highly viscous inlet that promotes fluid entrainment and thus maintains a separating film down to very low entrainment speed. The adsorbed polymer films are also able to maintain separation in stationary contact conditions. Randomly distributed copolymers do not show this type of behaviour. The friction reduction observed is more effective in unidirectional, mixed slidingrolling than in reciprocating, sliding conditions. However, it is found that functionalised polymers and conventional organic and molybdenum-based friction modifiers can be combined to provide effective friction reduction over the whole range of rubbing conditions.

Simulation and Field Measurements of Reliability Parameters of Dump Truck Hydraulic System

“…However, the use of a multicomponent working fluid leads to an increase in the labor intensity of seasonal maintenance of dump trucks [14,15]. Consequently, further works on the stabilization of the parameters of the working fluid is advisable to lead in the direction of stabilizing its temperature.…”

The Effect of Poly(alkyl methacrylate) Film-Formers on Pitting Performance of Driveline Fluids

“…Therefore, the improvements observed for the film-former should be a consequence of an improved boundary film. The graft copolymer film-former included in this study contains a functional graft comonomer which promotes polymer absorption to the metal surface [6] and results in the formation of a polymeric boundary film [3,4,5]. This boundary film protects steel surfaces and reduces pit formation.…”

“…A single film-forming PAMA was included in this study although numerous variations are possible [5]. The film-forming PAMA was a low molecular weight, graft copolymer prepared via a conventional free radical technique [6].…”

“…Further benefits in performance can be realized with functionalized PAMAs. It is well known that PAMAs with dispersant functionalities can improve soot dispersancy [1], but functionalized PAMAs can also contribute to boundary film formation [3,4,5]. Measurements of film thickness and friction coefficients revealed that several functional PAMAs promoted boundary film formation.…”

“…These films are maintained even in low speed and high temperature conditions and thus produce a reduction of friction and wear. Those film-forming PAMAs with controlled distribution of the functional monomer, such as block copolymers, were most effective [3,4,5].…”