Effect of olive leaf extract on the physicochemical properties of bio-based hair clipper lubricating oil developed from Neem seed oil

Nowadays, mineral-based oil is the most popular used lubricant in hair-clipper applications. However, producing these petroleum-based lubricants contributes to environmental pollution and climate change. This study explores the effect of olive leaf extract on the physicochemical properties of a bio-based hair clipper lubricating oil derived from neem seed oil. Neem crude oil was synthesised using a double transesterification method to develop a neem bio-based hair clipper lubricating oil. The produce neem bio-lubricant was blended with olive leaf extract at concentrations of 50 mg/ml, 100 mg/ml, and 200 mg/ml to enhance its anti-bacterial properties. The physicochemical properties of the blend, including viscosity, density, flash point, and pour point, were evaluated to determine its suitability as a sustainable alternative to conventional clipper oil. The results indicated that the flash point of the blended bio-based hair clipper lubricating oil was 180 °C, 195 °C, and 210 °C respectively, and they were found to be within the minimum requirement of the ISO standard value (EN ISO 2719) and above the conventional clipper oil (129 °C). From the pour point values obtained, the blended bio-lubricant offers a poorer value of 3 °C and 8 °C compared to that of ISO standard value (ISO standard 3016) and conventional clipper oil (-40 to -6 °C). It was also observed that the viscosities of 14.5 cSt, 15.6 cSt, and 16.7 cSt for the blended bio-lubricant conform with the minimum requirement of the ISO standard value (EN ISO 3104) and that of conventional clipper oil (7.5 to 90 cSt) at 40 °C. The density values of the blended bio-lubricant (0.897, 0.898, and 0.902) were found to be slightly above that of the ISO standard value (EN ISO 12185) and the conventional clipper oil (0.85–0.88). The antibacterial sensitivity test results of the blended bio-lubricant demonstrated a broad spectrum of activity against all tested microorganisms at both high and low concentrations, except for Escherichia coli, which showed moderate sensitivity at low concentrations (50 mg/mL). In general, the results of this work show that the bio-based hair clipper lubricating oil is a potential alternative to conventional clipper oil.