Effect of an alkali treatment on the development of cellulose pulp-based gel-like dispersions in vegetable oil for use as lubricants

The main aim of this study was to elucidate the influence of an alkali treatment on the rheological and tribological properties, and microstructure, of cellulose pulp-based gel-like dispersions potentially usable as biodegradable lubricating greases. For this purpose, cellulose pulp was treated with sodium hydroxide under different conditions of alkali concentration (20, 30 and 40%), temperature (20, 45 and 75 °C) and contact time (1 and 2 h). Favourable conditions relative to the rheological response of a commercial lithium lubricating grease used as benchmark were found to be 40% NaOH, 20 °C and 2 h. Gel-like dispersions with acceptable lubrication properties in terms of consistency indices, mechanical stability, and frictional and wear performance, were obtained by using a 6-7% (w/w) proportion of cellulose pulp.