Boundary Film Formation by Low Molecular Weight Polymers

Mitsui, Hideaki; Spikes, H. A.; Suita, Yoshikazu

doi:10.1016/s0167-8922(08)70476-0

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…These adsorbed layers result in a decrease in friction. On the other hand, some polymers exhibit a reduction in film thickness at low speeds, and this was ascribed to polymer depletion . It is therefore clear from the above that the ability of polymers to be entrained into the contact and form boundary films depends strongly on their affinity for the surface, relative to the interaction of the base oil with the surface.…”

Section: Introductionmentioning

confidence: 99%

Frictional Rheology of a Confined Adsorbed Polymer Layer

et al. 2009

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The sliding dynamics of a confined adsorbed polymer layer is investigated at the nanoscale. A combined mechanical and physical approach is used to model the rheology and structure of the adsorbed layer. The confinement at short distances governs the nanotribological behavior of the polymer layer formed close to the surface. It appears that the Amontons' proportionality between frictional and normal stresses does not hold here: the higher the contact pressure, the lower the friction. Besides, the sliding stress is strongly dependent on the velocity: it increases with the sliding velocity. Using a model based on the kinetics of formation and rupture of adhesive bonds between the two shearing surfaces theoretically accounts for the behavior of this system. This approach allows us to correlate the frictional properties to the molecular organization on the surfaces.

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Section: Introductionmentioning

confidence: 99%

Frictional Rheology of a Confined Adsorbed Polymer Layer

et al. 2009

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“…In the 1990s, it was shown that solutions of polyisoprene [5,6] and also some commercial, dispersancy-boosting viscosity modifiers [7] were able to form thick boundary films on polar surfaces and that these films could greatly reduce friction in low speed conditions [8]. This behaviour appeared to result from the physical adsorption of polymeric molecules on polar surfaces to form layers having higher polymer concentration than the bulk solutions and thus higher viscosity.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Friction by Functionalised Viscosity Index Improvers

Fan

Müller²,

Stöhr³

et al. 2007

Tribol Lett

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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.

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“…In 1997, the boundary film-forming properties of solutions of three polymers, polyisoprene, polystyrene, and polymethylmethacrylate, were measured using optical interferometry (Mitsui, et al (13)). These polymers are produced as chromatographic standards and are available at several different molecular weights with very low polydispersity.…”

mentioning

confidence: 99%

The Design of Boundary Film-Forming PMA Viscosity Modifiers

Müller¹,

Topolovec-Miklozic

Dardin

et al. 2006

Tribology Transactions

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Previous research has shown that some viscosity modifier additives are able to adsorb from oil solution on to metal surfaces to produce thick, viscous boundary films. These films enhance lubricant film formation in slow-speed and high temperature conditions and thus produce a significant reduction in friction. This article describes a systematic study of this phenomenon, which makes use of the versatile nature of polymethacrylate (PMA) chemistry. Dispersant polymethacrylates with a range of different functionalities, molecular weights, and architectures have been synthesized using controlled radical polymerization techniques. The influence of each of these features on boundary film formation and friction has been explored using optical interferometry and friction versus speed measurement. From the results, guidelines have been developed for designing PMAs having optimal boundary lubricating and, thus, friction-reducing properties.

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Boundary Film Formation by Low Molecular Weight Polymers

Cited by 10 publications

References 15 publications

Frictional Rheology of a Confined Adsorbed Polymer Layer

Frictional Rheology of a Confined Adsorbed Polymer Layer

Reduction of Friction by Functionalised Viscosity Index Improvers

The Design of Boundary Film-Forming PMA Viscosity Modifiers

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