Lube-Tech
advancements within this field. For OFMs, studies have noted the need for improvements within molecular structure to account for new changes [17]. The growing need for multi-faceted friction modifiers allows engines to be free of any possible issues. This includes promoting oxidative and anti-wear properties under certain conditions. As an engine undergoes combustion, exposure to water and high temperatures will degrade lubricants, leading to wear. Therefore, studies must look into friction modifiers as anti-wear and antioxidative additives to promote lubricant integrity while supplemented monofunctional friction modifiers are still used. Gatto et al. noted the anti-oxidative and wear properties working synergistically with other compounds during engine testing [18]. This interaction, observed between molybdenum and alkylated diphenylamines, proved that low concentrations of molybdenum within engine oil work as multifunctional. Although proper conditions and specific combustion rates are needed for each additive used, this study provides a base for how future research can work to improve synergistic relationships. Organomolybdeum friction modifiers also increase fuel efficiency and economy by nearly 1% [19]. Such an increase shows promise that friction modifiers hold for the future. As for this inverse relationship, modifying the chemical structure to synergise with other additives and knowing how it interacts with the engine surface will keep film thickness in check. Further research into organomolybdenum and molybdenum derivatives such as molybdenum dialkyl dithiocarbamate (MoDTC) shows that while effective as engine oils, their byproducts of molybdenum and sulphur degrade catalytic agents and automotive parts [20]. Therefore, the need for alternatives is imperative in the reduction of engine and lubricant wear.
In looking at alternative friction modifiers, oilless additives show promise in promoting excellent fuel economy for engines and maintaining traction reduction. Toyhama et al. observed certain
30 LUBE MAGAZINE NO.184 DECEMBER 2024
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.155 page 4
polymethacrylates (PMAs) as alternatives to traditional friction modifiers in oils [20]. For experimentation, researchers created PMAs of different molecular weights, each having a different number of dimethyl- amino-ethers (DMAE) attached to vary the quality of adsorption for experimentation. Results demonstrated a general decrease in friction coefficients with increasing sliding velocity, with the largest drops associated with PMAs of higher molecular weight and more DMAE groups. Figure 3 displays these results, with all groups following a similar downward trend [20]. Increased amounts of groups created stubborn films on interacting surfaces [20]; this property of lubricant thickness is imperative to observe the inverse relationship outlined earlier. Since these films are difficult to remove and effectively cover the engine surface material, this leads to decreased engine wear. Results also correlated increased functional groups with increased surface coverage for effective adsorption [20]. Further research must observe PMAs’ synergies with other fuel additives, such as organomolybdenum modifiers and anti-wear agents, and various engine conditions for effective commercialisation.
Figure 3: Friction reducing effects by PMAs introduction to various oils [20]
Along with observing PMAs as an alternative, synergies between organomolybdem modifiers and OFMs have been studied for an improvement to overall engine efficiency, fuel economy, and oil performance. Wang et al. observed the tribological performance of organomolybdem modifiers in
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