Production and evaluation of physicochemical, rheological, and tribological properties of Cucurbita pepo L. seed oil

In recent years, vegetable oils are seen as a safe alternative to mineral oil–based lubricants. In the present work, preliminary evaluation of the physicochemical, corrosion, thermal, rheological, and tribological properties of Cucurbita pepo L. oil (CPO) were carried out and compared with commercially available mineral oil, SAE 20W40, and other vegetable oils. The yield of CPO was found as 54.85% with iodine value, acid value, and saponification value of 105.52 ±0.12 gI₂/100 g, 0.4 ±0.52 mg KOH/g, and 147.26 ±0.11 mg KOH/g respectively. Palmitic acid (13.98%), stearic acid (13.55%), oleic acid (19.53%), and linoleic acid (50.07%) were major fatty acids present in CPO. The pour and flash points of CPO were - 8±0.67 ° C and 323±0.11 ° C respectively. The viscosities of CPO were 55.39 cSt at 40°C and 11.15 cSt at 100°C. The viscosity index was 180. From the tribology tests, it was observed that the coefficient of friction and wear scar diameter of CPO (0.0459±0.0002 and 0.413±0.0389) were comparable to that of SAE 20 W40 (0.0506±0.0356 and 0.333±0.0202). The extreme pressure properties of CPO were found relatively inferior in comparison to SAE 20W40 due to the presence of commercial additive package in SAE 20W40; however, it was observed that tribological properties of CPO (coefficient of friction and wear scar diameter) were better than some of the commonly studied vegetable oils.