Síntese e caracterização tribológica de biolubrificantes derivados de ácidos graxos comerciais

Abstract

The contrast of the scarcity of oil supply and the increase in demand for lubricants, together with strict environmental regulations and the need for sustainable and efficient solutions for friction reduction, has driven research into biolubricants. Currently, vegetable oils are the most used raw materials in the formulation of biolubricants, due to their good lubricating properties and high biodegradability. However, in general, these oils have some limitations such as a high pour point and low oxidative stability, and it is usually necessary to carry out chemical modifications to reduce these challenges. In this study, samples of biolubricants were synthesized from free fatty acids from castor oil and a residual fatty acid resulting from the deodorization stage of vegetable oils, mainly composed of palmitic and oleic acids, using the reactions of esterification, epoxidation and opening of the oxirane ring. To confirm the occurrence of modifications, chemical characterizations were carried out using Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) and to evaluate the performance, the physicochemical, thermo-oxidative and tribological properties were analyzed in the four-balls configuration using a sample of commercial mineral oil as a reference to discuss the results. The results obtained suggest that the synthesized products have the potential to be used as base oil for biolubricants, with coefficient of friction (COF) values ranging from 0.028 to 0.037, with a satisfactory result when compared with the reference sample that obtained a COF of 0.065. Furthermore, the possibility of using industrial waste in applications in the lubricant industry adds value to this byproduct and contributes to sustainable and economic development.