Tribological property of cellulose nanofiber water dispersion using various material pairs

Abstract

Cellulose nanofibers (CNFs) are synthesized by unraveling cellulose made from wood. CNFs have attracted significant attention among biomass materials owing to their excellent mechanical properties and wide range of applications. This study aims to elucidate the effects of CNFs as a lubricating additive. In order to accomplish this, CNFs were dispersed in water at densities of 0.02-1.0 mass%, and friction tests were performed using a ball-on-plate friction tester with a reciprocating motion configuration. Stainless steel (JIS-SUS304) and polyoxymethylene (POM) were used as sliding plates, while various materials were used for sliding balls. On both the SUS304 and POM plates, friction reductions were observed by adding only a small amount of CNFs (0.02 mass%). Although wear on the SUS304 plate reduced by 0.02 mass%, the water dispersion of CNFs was not distinct; it was observed only at densities of CNFs that were more than 0.2 mass%. On the POM plate, wear was induced by adding 0.02 mass% of CNF water dispersion. Adverse effects may arise with the addition of more than 0.2 mass% CNF. A distinctive feature observed in the water dispersion lubrication of CNFs was that a tribofilm is not formed due to the chemically inert nature of CNFs. It appears highly probable that in the water dispersion lubrication of CNFs, the physical effects of these fibers are much stronger than their chemical effects. These effects include rolling and/or sliding, which occurred in fullerene and carbon nanotubes.

Unravelling the unravelled : Microfibrillated cellulose as texture modifier in liquid and semi-solid foods

“…On the other hand, our results show no clear reduction in friction for increasing concentrations of MFC. This confirms recent work by Kinoshita et al (2020), who concluded that MFC does not form a tribofilm on the tribological surface and postulated that MFC can only reduce friction by physical rolling or sliding mechanisms. Moreover, as larger MFC flocs can be formed under shear (Karppinen et al, 2012;Saarikoski et al, 2012), MFC flocs might have formed in the current study that were too large to enter the gap between the tribo-surfaces.…”

“…As this yielded higher rather than lower friction coefficients, it was concluded that the intended increase in gap size was still not sufficient to entrain the microfibrillated material. Other researchers were able to determine friction properties of MFC dispersions using a ball-on-plate tribometer employing reciprocal motion (Kinoshita et al, 2020). These authors tested several sliding balls from several materials, which were moved against a stainless steel or polyoxymethylene plate.…”

Tribological properties of 100% cellulose nanofiber (CNF) molding under dry- and boundary lubrication-conditions at CNF/steel contacts

“…%) (Kinoshita et al 2020). Thus, the tribological properties of bulk CNFs remain unexplored although the CNFs have potentials to be used as a low-friction bulk material, according to the results of previous studies (Kinoshita et al 2020; Barari et al 2016).…”

“…However, the tribological properties of such a CNF-reinforced polymer composite was dominated by bulk polymer materials since the concentration of the CNFs in the composites was low (approximately 1.010 wt. %) (Kinoshita et al 2020). Thus, the tribological properties of bulk CNFs remain unexplored although the CNFs have potentials to be used as a low-friction bulk material, according to the results of previous studies (Kinoshita et al 2020; Barari et al 2016).…”