Síntese e características tribológicas de lubrificantes de base biológica obtidos a partir dos óleos de pequi, soja e mamona

• Ano de defesa: 2023
• Autor(a) principal: Ribeiro Filho, Paulo Roberto Campos Flexa
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Tribologia; Óleos vegetais; Esterificação; Epoxidação; Abertura do anel oxirano; Óleos lubrificantes; Óleo de soja; Óleo de mamona
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/71665

The demand for bio-based lubricants has grown considerably in recent years due to increasing environmental awareness among the public, governments, and industries. In this study, pequi, soybean and castor oils were used as a basis for obtaining biolubricants. From pequi oil, a sample of bio-based lubricant was obtained through hydrolysis (AGLP, Pequi Free Fatty Acids) and esterification (BLS, Synthetic Biolubricant) routes, using a long-chain alcohol (2-ethylhexanol). The hydrolysis (AGLS, Soybean Free Fatty Acids), esterification (BL1), epoxidation (BL2) and oxirane ring opening (BLOR) reactions using 2-ethylhexanol were used to obtain soybean oil-based biolubricants. While for samples based on castor oil fatty acids (AGLM, Castor Free Fatty Acids) the esterification (ERIC), epoxidation (EPOXIRIC) and oxirane ring opening routes using water (ORWATER) and 2-ethylhexanol (OR2EHRIC) were used as nucleophilic agents. The reaction products were characterized via Fourier-Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) analysis. The main physicochemical properties were determined according to standard ASTM methods. The frictional characteristics of the samples were obtained through tribological tests performed on a four-ball tribometer. A hydrotreated mineral lubricant (HMO) was used as a reference to evaluate the tribological behavior of biolubricants based on pequi and soybean oil. To compare the tribological characteristics of samples based on castor oil, 20W50 mineral oil was used. The result achieved for the coefficient of friction of the BLS sample was 30.7% lower than that of an HMO sample. Wear scar diameters (WSD) were 0.371 mm for BLS and 0.195 mm for HMO. The samples synthesized from soybean oil showed low coefficients of friction at all evaluated sliding speeds, even with an increase in load force and temperature. Among the samples based on castor oil, ORWATER showed the best frictional performance, showing an equivalent wear rate and a coefficient of friction 19.74% lower than mineral oil 20W50. Tribological performances indicate that bio-based samples obtained from pequi, soybean and castor oil can potentially be used as lubricant base oil.