Unexplored potential of acacia and guar gum to develop bio-based greases with impressive tribological performance: A possible alternative to mineral oil-based greases

A potential, sustainable, and economical eco-friendly alternative to harmful petroleum-based lubricants is a big challenge for the 21st-century lubricant industry. The present study explores, for the very first time, polysaccharide gums like gum acacia (GA) and guar gum (GG) as additives (0.5–10 %w/w) to enhance the extreme-pressure (EP) performance of greases (based on vegetable oil and organoclay). The greases are evaluated on a four-ball tester for the standard EP test (ASTM D2596). Adding GA or GG to greases enhances EP performance significantly. The performance ameliorates with the gum's concentration showing impressive results at higher concentrations (up to ≈ 60% better than a commercial grease). The superior performance is attributed to an in-situ formed polymer-layered silicate nanocomposite tribofilm at the interface via chemisorption (for GA) or physisorption (for GG). The formulated greases are a possible replacement for existing mineral oil-based commercial greases.