Abstract

The prolonged use of non-renewable mineral oils may pose significant challenges in the future if no viable alternatives are available. Existing vegetable oil alternatives are unsuitable for long-term use due to degradation during oxidation. In this study, vegetable oil was converted into methyl ester and subsequently blended with mineral oil to produce methyl ester corn oil (CO). This methyl ester CO was further combined with mineral oil containing titanium dioxide (TiO₂) and alumina oxide (Al₂O₃) additives, and the insulating properties of the resulting oil mixtures were evaluated. The results revealed that the viscosity, dielectric strength, and resistivity of methyl ester CO were lower than those of mineral oil, while its density was higher compared to Shell Diala B oil. The addition of Al₂O₃ enhanced dielectric strength, resistivity, density, and viscosity more effectively than TiO₂. As temperature increased, resistivity decreased. Among the samples, S6 exhibited the best density (0.847 g/cm³), which was 5% higher than that of S1 (0.809 g/cm³), thus complying with American Standard Testing and Material (ASTM) D1298 standards. S6 also showed the best viscosity (2.82 cSt), which was 38% lower than that of S1 (4.54 cSt), meeting ASTM D445 standards. At 20 °C, sample S8 demonstrated the highest resistivity (0.366 GΩ·m), which was 57% lower than that of S1 (0.850 GΩ·m). At 90 °C, its resistivity decreased to 0.172 GΩ·m, 64% lower than that of S1, in accordance with International Electrotechnical Commission (IEC) 64422-2013 standards. S8 also exhibited the best dielectric strength (28 kV/2.5 mm), only 11% lower than that of S1 (31.6 kV/2.5 mm), thereby meeting ASTM D887 standards (26 kV/2.5 mm).

Keywords

Mineral oil alternatives, Methyl ester corn oil (CO), Dielectric strength, Resistivity, Viscosity, Nanoparticle additives.

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