Effect of Molecular Weight on Tribological Properties of Polyether Amine Derivatives under Different Contact Modes

Abstract

The requirements for the fuel economy of modern industry continue to drive the progress of low-viscosity lubricants. The present work reports the application of polyether amine derivatives as friction modifiers to improve the tribological properties of low viscosity poly-alpha-olefin. Three polyether amine derivatives with different molecular weights were synthesized, the tribological properties of which were systematically investigated under three different contact modes. These functionalized polymers exhibited significant friction reduction and wear resistance properties in the point-on-flat and line-on-flat friction tests, but just showed anti-wear performance in the severe point-to-point contact mode. The results exhibited that molecular weights of the polymers had a direct effect on their tribological properties. The increase of molecular weight in a certain range was beneficial to the improvement of tribological properties, but further undue increase will rather reduce the friction reduction and wear resistance performances. It can be indicated that the number of oxygen atoms increased with the molecular weight of the polymer, which will be conductive to the adsorption of the polymer on the metal surface. However, when the molecular weight of the polymer exceeds a certain value, the steric hindrance of the molecules adsorbing to the metal surface increases, which in turn has a negative impact on the tribological properties.

Ionic Liquid/Functionalized Graphene Oxide as a Nano Additive for Corrosion Protection and Lubrication

“…To better understand the lubrication mechanism of the lubricating additives, the crystal structure of the tribofilm was analyzed by Raman spectroscopy and the experimental results are shown in Figure a. The figure shows that WP oxidation occurred during the friction process, forming the characteristic peaks of Fe 2 O 3 and Fe 3 O 4 . In the Raman spectroscopy of Ch–Met/GO, the characteristic peak of Fe 2 O 3 disappears; however, there is a strong characteristic peak of Fe 3 O 4 , indicating that Ch–Met/GO inhibits the oxidation reaction in the friction process to a certain extent.…”

“…The figure shows that WP oxidation occurred during the friction process, forming the characteristic peaks of Fe 2 O 3 and Fe 3 O 4 . 49 In the Raman spectroscopy of Ch−Met/GO, the characteristic peak of Fe 2 O 3 disappears; however, there is a strong characteristic peak of With the progress of the friction process, Fe 2 O 3 and Fe 3 O 4 fell off the surface of the friction pair, forming pits, and the fallen Fe 2 O 3 and Fe 3 O 4 floated in WP to form abrasive particles, resulting in abrasive wear. Although Ch−Met/GO effectively inhibited the formation of Fe 2 O 3 during the friction process, a large number of Fe 3 O 4 were generated during the friction process, resulting in severe abrasive wear.…”

On the Structure–Activity Relationship of Glyceryl oleate Friction Modifiers and Its Synergistic Mechanism on Phosphate ester Antiwear Additives

“…Unfortunately, this disordered carbon is randomly distributed and does not possess excellent mechanical properties. Under the action of high shear stress, it is prone to be sheared and accumulated at the edge of the wear scar [9,48], which is also the reason for the insigni cant improvement of the friction reduction effect. In addition, Raman peaks with different intensities were detected near 2898 cm-1 on the wear surfaces lubricated by GMO and GDO, respectively.…”

“…Polymer friction modi ers (PFMs [9]) consist of a high proportion of polar, non-polar monomers and are commonly used as viscosity index modi ers. It is generally believed that the polar segments of PFMs adsorb at the metal interface and the non-polar segments extend into the base oil to form a uid layer with high viscosity and exert friction-reducing properties [10].…”

“…In terms of differences in hydrocarbon tail chains, Li et al [9] studied the effect of molecular weight differences in polyether amine derivatives on tribological properties. The results show that the tribological properties rst improve and then deteriorate with the increase of molecular weight, which is attributed to the increase of the O active site facilitating the adsorption of additives to the metal interface and the formation of chemical reaction lm during the friction process.…”