Mixtures of vegetable oils and di-2-ethylhexyl-sebacate as lubricants

Abstract

Lubricants based on vegetable oils are growing in popularity in various applications. Environmentally friendly, vegetable oils and their derivatives constitute alternatives to mineral-based lubricants. Soybean oil, sunflower oil and rapeseed oil have better viscosity indices than mineral oils and even some synthetic oils, are biodegradable and have low production costs. However, vegetable oils have disadvantages, such as poor thermo-oxidative stability due to the carbon-carbon double bonds and poor low-temperature properties, which limit their use as lubricant base stocks. This study describes new base-stock oils obtained from mixture of vegetable oils and di-2-ethylhexyl-sebacate synthetic oil, which become lubricants when additives are introduced. These mixtures offer a large range of kinematic viscosities, while their pour points are under −33°C and their flash points over 240°C. The copper strip corrosion test result is 1a. The diameters of wear scars measured under four-ball testing (40 dyn) are less than 1 mm. A differential scanning calorimetry study and a thermo-gravimetric study under a nitrogen atmosphere for the mixed oils are reported. In the former study two-endothermic processes were observed between −15°C and −50°C. In the thermo-gravimetric analysis curve the weight loss is specific for each vegetable and synthetic oil component. From these studies a higher thermal stability was observed for vegetable oils than for ester oils, and it was concluded that the mixtures of vegetable and synthetic oils of diester type are physically homogeneous mixtures. The low production cost of lubricants based on vegetable oils makes them attractive alternatives for mineral oil based lubricants. Overall the mixtures of vegetable and ester oils can be competitive base oils for environmentally friendly lubricants.

Formation of an adsorption film of MoS2 nanoparticles and dioctyl sebacate on a steel surface for alleviating friction and wear

“…Di-2-ethylhexyl sebacate (dioctyl sebacate, DEHS or DOS) is a diester lubricant synthesized from sebacic acid and 2-ethylhexanol. DOS not only has the function of base oil by itself but is used to prepare the mixing lubricating oils of DOS and vegetable oils as well [32]. DOS has been applied as industrial lubricants for aircraft engines and air cooled combustion motors [33].…”

Synthesis and properties of trimethylolpropane trioleate as lubricating base oil

“…With the rapid development of modern industry, mechanical equipments undergo more severe conditions like high speed, heavy load and elevated temperature, which require the lubricating oils with good anti‐wear, load‐carrying and anti‐oxidation properties. However, mineral oils can no longer satisfy the increasingly stringent demands in many specific application fields . In addition, mineral oils are non‐renewable and are potential threat to the environment .…”

Mixture of safflower oil and synthetic ester as a base stock for biodegradable lubricants

“…However, there is a major constraint in using SE‐based lubricants because of their fairly high cost. For the aforementioned reasons, a mixture of plant oil and SE‐based products will become a crucial part of new lubricant technology, which will help in reducing the dependence on conventional mineral oils . Although many have reported the physical and chemical degradation of the base stocks by PDSC, DSC, thermal gravimetric analysis or thin film micro oxidation test, there are only few reports on bulk oxidation tests such as RPVOT.…”