Lubricants that are based on renewable raw materials have drawn increased attention in various applications, especially those related to the food industry. Due to the high requirements of environmental protection, there is a need to develop biodegradable base oils that are environmentally friendly and do not contain harmful components. The objective of the research was to obtain a base oil with a certain viscosity and certain desired lubricating properties. Base oils were obtained from Crambe abyssinica oil by means of blending with synthetic oil and oxidation. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without CO₂ as a solvent. As a final result of this study, oil bases meeting the viscosity requirements and showing suitable lubricating properties were obtained. The Raman spectra of the obtained oils were evaluated.

Raw vegetable oil from Crambe abyssinica was subjected to oxidative treatment to enhance its viscosity. The oxidation processes were carried out in the presence of N-hydroxyphthalimide with or without supercritical CO₂ as a solvent. Four spectroscopic techniques (Raman, UV-VIS, FT-IR, NMR) were applied to assess the chemical changes taking place during the oxidation. Raman and NMR spectroscopy proved best in the assessment of the chemical transformations leading to increased viscosity of the modified vegetable oil.

The paper presents the research results on the relations between additive content and tribological, rheological, and oxidizing properties of lubricating greases. The greases were based on linseed oil, thickened with amorphous silica Aerosil^® and modified with different concentration of polyvinylpyrrolidone. The greases were tested tribologically according to the test on T-02 testing machine and referred to the unmodified control. The evaluation of tribological properties was based on the following parameters: welding load, scuffing load, limiting load of wear, limiting load of scuffing, and limiting pressure of seizure. The results of tribological research revealed the most promising impact of the 3% addition of polyvinylpyrrolidone. All of the crucial parameters were improved in comparison to the unmodified control grease. The spectral analyses revealed that some of the components undergo oxidation during mechanical forces, leading to the formation of the oxidized organic compounds. These substances generated a layer, counteracting the wear of lubricated tribosystem. The improved resistance to oxidation of the tested lubricants with polyvinylpyrrolidone can be explained by the presence of highly hydrophilic pyrrolidone groups and hydrophobic alkyl group in polyvinylpyrrolidone (PVP) molecule. These compounds combine with hydrocarbon chains of linseed oil and act synergistically with the silicon dioxide molecules. The introduction of polyvinylpyrrolidone caused the improvement in dynamic viscosity at lower shear rates and a significant change of viscosity in low temperatures. An increased value of the yield point of the tested lubricating compositions after introduction of the additive was also observed.

Effect of modifying a vegetable grease with different amounts of chokeberry biocarbon on its tribological and rheological properties. The aim of the research was to investigate the effect of the incorporation of biochar derived from the pyrolysis of chokeberry biomass at 500 and 700 °C respectively, in lubricants formulated with vegetable oil, on their functional characteristics in terms of tribology and rheology. Fumed silicon dioxide was utilized as a thickening agent, ensuring the production of lubricants with a consistency class of II. The biochar was introduced into the lubricating formulations in concentrations of 1, 3, and 5%. A rapeseed-based grease with commercial activated carbon served as the reference sample. The research focused on assessing how this innovative additive influenced both the tribological and rheological behaviors of the resulting lubricants. The study evaluated the effects of chokeberry-derived biochar on the wear resistance and scuffing prevention properties of the vegetable-based greases. Additionally, the biochar’s influence on various rheological parameters such as flow curves, viscosity profiles, hysteresis loops, and viscoelastic characteristics was analyzed. Results demonstrated that the biochar additive considerably enhanced the tribological and rheological performance of the tested rapeseed-based grease.

This paper describes an investigation of the effects of silicone-containing additives on the tribological and rheological properties of various lubricant blends. Aerosil^® and layered silicate were used to modify lubricants containing rapeseed, linseed and soy oil that were thickened with soap thickener. Tribological tests were carried out using a four-ball concentric contact tester. On the basis of the data obtained from the tribological studies of the selected lubricant blends, it was concluded that the addition of amorphous silica increased the anti-seizure and anti-wear properties of the tested lubricants. The addition of montmorillonite caused a significant increase in the values of the individual parameters determining the level of lubricating properties of the tested lubricants in comparison with the lubricants modified with the silica additive. Based on the results of the rheological tests of the studied lubricants, it was found that the applied additives caused a change in the dynamic viscosity and chemical structure of the tested lubricants, expressed by a change in the values of the G′ and G″ indices. The main finding of this manuscript was to demonstrate that the use of montmorillonite and aerosil additives improves the functional properties of vegetable-based plastic lubricants. The performance of tribological and rheological tests is of great scientific importance, as it provides an insight into the interaction of siliceous additives with the results of tribological tests on vegetable-oil-based greases. These findings make it possible to determine the behaviour of the lubricant under load and add to the knowledge of vegetable greases.