The Influence of Natural Ester Aging Conditions on its Neutralization Value in Terms of the Limits Given in the IEC 62975

The main objective of the research was to analyze the influence of natural ester aging conditions on its neutralization value (acidity) in terms of the limits given in IEC 62975. To achieve this goal, accelerated hydrolytic and oxidative aging of the natural ester was carried out. The properties of the natural ester were tested before and after the aging process, such as acidity, water content, interfacial tension, breakdown voltage, and dielectric dissipation factor. Moreover, using a gas chromatograph coupled with a mass spectrometer, fatty acid analysis was performed. The research results presented in the article showed that both hydrolytic and oxidative aging of the natural ester leads to the formation of free acids, which causes an increase in the acidity. Analysis of saturated and unsaturated fatty acids in the natural ester allowed for the explanation of changes in the ester properties. The article shows that in the case of hydrolytic aging, an increase in the acidity does not have to be accompanied by a deterioration in the other properties of the natural ester, and in such a case ester reclamation may not be necessary.