The influence of montmorillonite content on change the physicochemical properties of lubricating greases produced from vegetable base oil

Abstract

The publication presents the results of investigations into the influence of different amounts of a modifying additive on the physicochemical properties of selected lubricating compositions. Montmorillonite, as a representative of stratified silicates, was used to modify lubricating grease produced from a vegetable base oil, and lithium stearate was used to thicken it. Investigations of the physicochemical properties of the base lubricating grease were carried out and compared with the results obtained for lubricating greases containing the modifying additive. The selected parameters were penetration, penetration after prolonged kneading, dropping point, emission of oil from grease, anticorrosive properties by dynamic method, and mechanical stability – an attempt to roll out and oxidize the lubricant with a PetroOxy apparatus. Based on the results of physicochemical tests, it was determined that the applied modifying additive causes an increase in the dropping point, which limits the applicability of lubricating greases, as well as a decrease in oil emission, which was responsible for the lubricating effectiveness of the tested lubricants. It had a positive effect on mechanical stability and the tested lubricants were not disqualified from use in established applications, reducing the degree of corrosion on ball bearings working in the presence of the lubricating greases during testing. This had a positive effect on the condition of machines and devices where the lubricating greases are used and increased the oxidative stability when its content in the lubricating grease was at least 5%. This figure represents the upper limit of the modifying additive content in the lubricating greases.