Tribological Study Of Jatropha Oil As Boundary Lubricant

• Main Author: SYAH LUBIS, ABDUL MUNIR HIDAYAT
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/15126/1/Munir-Final%20Thesis-after%20viva%20%282%29.pdf; http://utpedia.utp.edu.my/15126/
• Institution: Universiti Teknologi Petronas

Application of jatropha oil as boundary lubricant has been studied. In this research, boundary friction and wear preventive characteristics of jatropha oil as boundary lubricant were established. Structural modification and the use of selective additives were also studied to solve poor oxidation behavior of jatropha oil problem which could influence the oil performance as boundary lubricant. The main objectives of this research are: (i) to synthesize the derivatives of jatropha oil and establish their boundary friction, wear preventive, and thermo-oxidation properties, and (ii) to solve oxidative stability and wear preventive problem/issues of crude jatropha oil by the use of antioxidant additives and anti-wear additives. The friction and wear preventive properties were characterized by four-ball method. The thermo-oxidative behavior of the oil was studied by thermo-gravimetric analysis (TGA) and air bubbling oxidation methods. The modification of unsaturated carbon bond contained in crude jatropha oil (CJO) via epoxidation process was able to improve thermo-oxidative properties of jatropha oil. Epoxidized jatropha oil (EJO) show a higher first thermal degradation point of jatropha oil under oxidized condition compared to crude jatropha oil. It is also show significant reduction in the viscosity changes caused by high temperature obtained by air bubbling oxidation method. However, no significant effect to friction coefficient (μ), the value were μ CJO = 0.067 while μ EJO =0.065. But the epoxidized jatropha oil was found to show better wear preventive characteristics compared to jatropha oil, which average wear scar diameter of EJO is 0.581 mm while average wear scar diameter of CJO is 0.607 mm. The modification of unsaturated carbon bond via two stage esterification processes was not significantly able to improve the thermo-oxidative properties of jatropha oil. The first thermal degradation point of esterified fatty acid jatropha oil (EFA-JO) under oxidized condition was found lower than crude jatropha oil, although the viscosity changes caused by high temperature obtained by air bubbling oxidation method was significantly lower than jatropha oil. viii Friction coefficient of esterified fatty acid jatropha oil (EFA-JO) also show a higher value compared to crude jatropha oil (μEFA-JO = 0.075) and also show higher wear than crude jatropha oil (average wear scar diameter of EFA-JO is 0.779 mm). Addition of the octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as an antioxidant additive was able to improved thermo-oxidative properties of jatropha oil. Addition 1-5 wt. % of this additive could raise the first thermal degradation point of jatropha oil under oxidized condition from 168°C up to 200°C. It is also show significant reduction in the viscosity changes caused by high temperature obtained by air bubbling oxidation method. Addition of tricresyl phosphate (TCP) as an anti-wear additive was significantly improved wear preventive capability of jatropha oil. Addition 1-5 wt. % of this additive to jatropha oil could reduce the average wear scar diameter of test the bearing from 0.607 mm up to 0.328 mm. Blend of tricresyl phosphate and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate also found able to improves friction, wear, and thermo-oxidative properties of crude jatropha oil. The study also found that the optimum blend, consisting of 3.59 wt.% of octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 4.42 wt.% of tricresyl phosphate in crude jatropha oil, has friction coefficient of μ = 0.045 and average wear scar diameter of 0.324 mm. Further studies related to enhancement of boundary lubrication properties of jatropha oil such as structural modification or the use additives are highly recommended.