Use of Electrospun Cellulose Acetate/Silica Composites as Multifunctional Ingredients in Eco-Friendly Semisolid Lubricant Formulations

Abstract

Cellulose acetate/silica (CA/SIL) nanocomposites are prepared by electrospinning and investigated as multifunctional ingredients in eco-friendly semisolid lubricant formulations. The structuring ability of these electrospun composites in castor oil and the antifriction and antiwear properties are examined through rheological and tribological experiments. The multifunctionality of CA/SIL composites arises from a balance between the silica content and the formation of nanofiber-dominated structures. The linear viscoelasticity functions in the oleo-dispersions increase by several orders of magnitude with both the spinning solution concentration and the CA:SIL ratio. However, the rheological response primarily depends on the morphology of the nanofiber mat obtained, specifically nanofiber diameter and the presence of beads. In contrast, the silica content significantly impacts the tribological performance of the oleo-dispersions regardless of nanofiber morphology. For similar nanoarchitectures and rheological responses, the friction coefficient is reduced from 0.227 to 0.108 by incorporating silica in a 10:1 CA:SIL ratio, compared with the SIL-free electrospun CA nanofibers, while wear is completely prevented. Increasing the composite concentration from 5 to 12.5wt. % enhances wear protection and the gel strength of oleo-dispersions, for example, the plateau modulus rises from 800 to 42,000Pa using a composite with a 10:1 CA:SIL ratio