Rheological Characterization of Oleo-Dispersions Based on Montmorillonite/Cellulose Acetate Phthalate Hybrid Fibers and Castor Oil for Lubricant Purposes

Pollution reduction, oil depletion and global concern for a better environment are the three pillars of the modern lubricants industry. New formulations must therefore comply with current regulations to be more environmentally friendly. Lubricating greases are semi-solid lubricants obtained by dispersing a thickener in a lubricating fluid. In fact, traditional greases use mineral oil as the base fluid and metal soaps as thickeners. With the aim of reducing environmental impact, researchers have developed new greases using vegetable oil, but we cannot forget the role of the thickener. Some biopolymers have attracted interest for this function, such as lignin [1] or cellulose [2]. In addition, electrospinning is an interesting nanofabrication technique for obtaining thin biopolymer fibers. In fact, new semi-solid lubricants have been developed that thicken castor oil with electrospun cellulose acetate-phthalate fibers (CAph) [3]. This study investigates the incorporation of montmorillonite nanoclay into the electrospinning process of cellulose acetate phthalate to produce hybrid fibers. The aim is to enhance the mechanical properties of the pure polymer fibers and thicken castor oil. The rheological properties of the hybrid electrospinning solutions and the developed semisolid lubricants were evaluated, with a focus on the montmorillonite load. The viscoelastic properties of the oleo-dispersions were influenced by both the addition of clay and the morphologies of the nanostructures. This behaviour was found to be similar to that observed in lithium commercial lubricant greases. Thus, the potential of using hybrid nano- and micro-structures as the foundation for fabricating oleo-dispersions was illustrated.