MODIFICATION OF THE OPERATIONAL PROPERTIES OF VEGETABLE-BASED ENGINE OILS
DOI:
https://doi.org/10.30857/2786-5371.2026.4.7Keywords:
ecology, vegetable oil, biolubricant, transesterification, epoxidation, oil quality indicators, viscosity index, biodegradability, tribology, additivesAbstract
Purpose. The study aims to evaluate the effect of chemical modification of rapeseed oil on its performance properties and its potential as a renewable component of lubricants for small two-stroke engines.
Methodology. Refined rapeseed oil and its 2-ethylhexyl ester, obtained through a two-stage conversion of triglycerides, were investigated. Kinematic viscosity was determined by the capillary method according to ISO 3104:2023 at 40 and 100 °C using a VPZh-2 viscometer with a 1.31 mm capillary and KV-002 thermostat. Biodegradability was evaluated by CO₂ evolution in an aqueous aerobic medium. MOTUL 100 2T mineral oil was used as the reference. Comparative evaluation of the initial and modified oils was performed to establish the effect of esterification on the main material properties and assess changes in its performance potential for subsequent application in engines.
Findings. After modification, viscosity decreased by 82.9% at 40 °C and by 73.2% at 100 °C. The viscosity index increased from 216 to 224, while the pour point decreased from -12 to -31.3 °C. Compared with MOTUL 100 2T, the 2-ethylhexyl ester has a higher viscosity index and a lower pour point. The results show that chemical modification substantially reduces rapeseed oil viscosity and improves its low-temperature flow properties.
Originality. Conversion of rapeseed oil into 2-ethylhexyl ester simultaneously reduces viscosity and substantially improves low-temperature flow while maintaining a high viscosity index.
Practical value. The obtained ester is a promising renewable component of lubricants for small two-stroke engines. Further tribological and engine tests are required to confirm its suitability. Further evaluation of the ester in renewable lubricant formulations for engines remains warranted in practice.
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References
Uppar R., Dinesha P., Kumar S. A critical review on vegetable oil-based bio-lubricants: preparation, characterization, and challenges. Environment, Development and Sustainability. 2023. Vol. 25. P. 9011–9046. DOI: https://doi.org/10.1007/s10668-022-02669-w.
Hamnas A., Unnikrishnan G. Bio-lubricants from vegetable oils: characterization, modifications, applications and challenges – review. Renewable and Sustainable Energy Reviews. 2023. Vol. 182. Art. 113413. DOI: https://doi.org/10.1016/j.rser.2023.113413.
Salimon J., Salih N., Yousif E. Biolubricants: raw materials, chemical modifications and environmental benefits. European Journal of Lipid Science and Technology. 2010. Vol. 112. P. 519–530. DOI: https://doi.org/10.1002/ejlt.200900205.
Heikal E. K., Elmelawy M. S., Khalil S. A., Elbasuny N. M. Manufacturing of environment friendly biolubricants from vegetable oils. Egyptian Journal of Petroleum. 2017. Vol. 26. P. 53–59. DOI: https://doi.org/10.1016/j.ejpe.2016.03.003.
Erhan S. Z., Sharma B. K., Liu Z., Adhvaryu A. Lubricant base stock potential of chemically modified vegetable oils. Journal of Agricultural and Food Chemistry. 2008. Vol. 56. P. 8919–8925. DOI: https://doi.org/10.1021/jf801463d.
Sharma R. V., Somidi A. K., Dalai A. K. Preparation and properties evaluation of biolubricants derived from canola oil and canola biodiesel. Journal of Agricultural and Food Chemistry. 2015. Vol. 63. P. 3235–3242. DOI: https://doi.org/10.1021/jf505825k.
McNutt J., He Q. S. Development of biolubricants from vegetable oils via chemical modification. Journal of Industrial and Engineering Chemistry. 2016. Vol. 36. P. 1–12. DOI: https://doi.org/10.1016/j.jiec.2016.02.008.
Borugadda V. B., Goud V. V. Improved thermo-oxidative stability of structurally modified waste cooking oil methyl esters for bio-lubricant application. Journal of Cleaner Production. 2016. Vol. 112. P. 4515–4524. DOI: https://doi.org/10.1016/j.jclepro.2015.06.046.
Mannekote J. K., Kailas S. V. Experimental investigation of coconut and palm oils as lubricants in four-stroke engine. Tribology Online. 2011. Vol. 6. P. 76–82. DOI: https://doi.org/10.2474/trol.6.76.
Reeves C. J., Menezes P. L., Jen T. C., Lovell M. R. The influence of fatty acids on tribological and thermal properties of natural oils as sustainable biolubricants. Tribology International. 2015. Vol. 90. P. 123–134. DOI: https://doi.org/10.1016/j.triboint.2015.04.021.
Reeves C. J., Siddaiah A., Menezes P. L. A review on the science and technology of natural and synthetic biolubricants. Journal of Bio- and Tribo-Corrosion. 2017. Vol. 3. Art. 11. DOI: https://doi.org/10.1007/s40735-016-0069-5.
Kulkarni R. D., Deshpande P. S., Mahajan S. U., Mahulikar P. P. Epoxidation of mustard oil and ring opening with 2-ethylhexanol for biolubricants with enhanced thermo-oxidative and cold flow characteristics. Industrial Crops and Products. 2013. Vol. 49. P. 586–592. DOI: https://doi.org/10.1016/j.indcrop.2013.06.006.
Cecilia J. A., Ballesteros Plata D., Alves Saboya R. M., Tavares de Luna F. M., Cavalcante C. L., Jr., Rodríguez-Castellón E. An overview of the biolubricant production process: challenges and future perspectives. Processes. 2020. Vol. 8. Art. 257. DOI: https://doi.org/10.3390/pr8030257.
Mobarak H. M., Mohamad E. N., Masjuki H. H., Kalam M. A., Al Mahmud K. A. H., Habibullah,M., Ashraful A. M. The prospects of biolubricants as alternatives in automotive applications. Renewable and Sustainable Energy Reviews. 2014. Vol. 33. P. 34–43. DOI: https://doi.org/10.1016/j.rser.2014.01.062.
