Chemically modified palm kernel oil ester: A possible sustainable alternative insulating fluid

The demand for a sustainable and non-toxic alternative insulating fluid has been on the increase because of the negative environmental impact of mineral-based insulating fluids. Natural ester appeared to be a viable alternative, but it has poor thermo-oxidative properties and higher melting temperature. This report presents the influence of chemical modification on the properties of natural ester-based alternative insulating fluid. Alkyl ester derivatives were synthesized from laboratory purified palm kernel oil. A straight chain alkyl ester was first synthesized to enhance the flow properties of the oil. It was then followed by a process that converts the double bond to an epoxy group. Side-branched ester samples were synthesized from the laboratory synthesized epoxy alkyl ester of palm kernel oil. The chemical modification was performed through esterification reaction involving the epoxy alkyl ester of palm kernel oil and acid anhydrides under nitrogen and in the presence of boron trifluoride etherate as catalyst. The reactions were monitored and the products confirmed using FTIR and GC–MS. The melting point and thermo-oxidative stability of the fluids were examined using Differential Scanning Calorimetry (DSC). The melting point of the ester derivatives was found to reduce with side chain attachment and antioxidant significantly improved the thermal stability. The dielectric behavior and electrical breakdown properties of the ester derivatives were analyzed and compared. The dielectric loss was dominated by mobile charged particles and the charged particles appeared to exhibit faster dynamics compared with purified palm kernel oil. This may be attributed to the mobility of the charges which is related to the viscosity of the esters. The esters possessed excellent breakdown strengths suggest that the processing to optimize the physical properties did not have a negative influence on the electrical breakdown strength. This product may prove useful as an insulation fluid in Electrical Power Transformers.