Influence of manufacturing temperature on the rheological behavior of some vegetable lubricating greases (original) (raw)

Process Temperature Profile and Rheological Properties of Greases from Vegetable Oils

Green and Sustainable Chemistry, 2014

Greases are composed by lubricating oil dispersed in a thickener that can be a metal soap, polymers or clays. Grease production using vegetable oils is increasing due to biodegradability requirements. Since vegetable oils present a worse oxidation and hydrolysis stability than mineral oils, it is usually difficult to produce a neutral grease using them. Four greases were produced using soybean oil as lubricating oil and lithium 12-hydroxystearate as thickener. The maximum temperature of reaction was ranged from 230˚C to 120˚C in a bench process and a reduction in the final product acidity was observed (from 8.2% acid to 0.05% alkaline). Traditional tests to evaluate thickener structure resistance like 10,000-time worked penetration, roll stability and dropping point were performed and results compared. In addition, rheological tests were performed and the results were also compared. Results indicate that it is possible to produce a quite neutral grease using vegetable oils with good thickener structure properties.

Studies Concerning Vegetable Oils Used as Biodegradable Lubricant

2019

Biodegradable oils are at present a powerful performance in the field of lubrication of machinery and machines that work predominantly under conditions that make it possible to pollute the environment. This refers to machinery and equipment in agriculture, construction industry, marine, forestry, printing, drilling, railways, automotive, and food industries, where environmental pollution is reduced as a result of losses of lubricants on soil or water. Viscosity, shear stress, shear rate, yield value, plastic, pseudoplastic and thixotropic models, viscometer and rheometer types are the major issues discussed in rheology. This article proposes several dependency of dynamic viscosity with shear rate. Rheological characteristics of vegetable oils were measured with rotational co-axial cylinder rheometer at different temperatures of 40-90 °C.

Eco-friendly Additivated Lubricating Greases Made of Agricultural Resources

Revista de Chimie

The purpose of this work is to to develop a simple technology for producing high quality greases from renewable and handy resources in a specific region: West Africa. New lubricating greases were formulated based on palm oil and corn oil with 20% wt. calcium stearate prepared in situ at 100oC and by adding during manufacture crystalline cellulose or Kraft lignin in different concentration (5%, 10% or 20% w/w). These additives significantly improve the rheological parameters, consistency and mechanical stability of the products. Products with 20% (w/w) cellulose or 20% (w/w) lignin added are of particularly good quality These greases could be used in domestic economy, for the agricultural equipment, but also in other industries such as food industry or paper mills being suitable for valves and fittings, gearboxes, rolling bearing.

Influence of Additive concentration in Soybean Oil on Rheological and tribological Behavior

INCAS BULLETIN, 2018

The rheology of vegetal oils, additivated or not and the factors that influence their viscosity have been studied by specialists, in order to introduce these oils as lubricants in green industries as agriculture, food processing, transportation and for complying with environmental and health regulations; the vegetal oils are also envisaged as an eco-friendly alternative to similar mineral and synthetic products. This study presents the influence of nature and concentration of additive in soybean oil on its rheological and tribological behavior, reflected by shear stress-shear rate, viscosity-temperature curves and by the wear scar diameter (WSD) after testing the formulated lubricants on a four-ball machine.

Evaluation of lubricant properties of vegetable oils as base oil for industrial lubricant

IOP Conference Series: Materials Science and Engineering

The possible insufficiency of oil resources in the future and the poor bio-degradability of mineral oil based lubricant resulted in the need of bio lubricant. Bio-based products are typically produced from vegetable oils. For the present study rice bran oil [RBO], jatropha oil [JO] and karanja oil [KO] are selected as the base oils for the industrial lubricant. Friction and wear characteristics are evaluated on four ball tester and the initial findings show that wear scar of RBO is lowest, this is because of the presence of natural anti-oxidants like gamma oryzanol. The coefficient of friction and wear of all the oils were evaluated as per ASTM D5183 and ASTMD 4172 respectively. Viscosity of the oils are tested on Brookfield rheometer and KO is having high viscosity when compared to other two oils but the change in viscosity with temperature is low for both RBO and JO. Chemical properties of the oils are conducted as per IS: 548 (Part 1)-1964. The iodine value for KO is less when compared to RBO and JO. Less iodine value is required to impart better oxidation stability. Thermogravimetric analysis showed that RBO is stable till 320 ˚C and KO, JO started degrading at 200 ˚C. The thermal properties of all the oils are measured and RBO has shown better properties at wide range of temperatures. The disadvantages of vegetable oils like oxidative stability need to be improved by adding additives and by chemical modifications.

Suitability of vegetable oils as industrial lubricants

Journal of Synthetic Lubrication, 2004

This paper reports on the application-relevant properties of sixteen commercially available vegetable oils tested without additives in accordance with established standards. Their per$ormance was compared with each other and with that of mineral oil and synthetic esters. The basic characteristics of all the oils (density, viscosity? pour point, cloud point, jlash point and fire point) were initially determined. A chemical analysis of the vegetable oils was carried out to determine the acid value, saponification and iodine numbers. Additionally, the oxidative stability of all the oils was tested. The tribological per$ormance, lubrication, and wear protection of the oils were judged under abrasive as well as adhesive conditions. The comparative study of the test vegetable oils showed great differences in the properties of the oils. All the vegetable oils tested revealed weak points during testing, including rape seed and castor oils, which have established uses in industry. This study shows that certain vegetable oils, such as sesame oil and wheatgerm oil, may have potential for use in selected technical applications. The mineral oil and synthetic esters showed markedly superior per$ormance when tested under adhesive conditions, but comparable behaviour to the other oils under abrasive conditions.

Comparison of selected vegetable oils rheologic properties

Journal on Processing and Energy in Agriculture, 2017

The article is focused on measuring and comparison of rheologic parameters of selected vegetable oils. Determined were these properties: density, dynamic, kinematic viscosity and fluidity. Measurements were performed in approximate temperature range (5-32) °C on two samples of vegetable oils: sunflower oil and olive oil. Density of vegetable oils was determined by oscillation method using digital densimeter Anton Paar DMA 4500 M at different temperatures. For dynamic viscosity measurement was used rotational viscometer Anton Paar DV-3P, which principle is based on dependency of sample resistance against the probe rotation. Other rheologic parameters as kinematic viscosity and fluidity were determined according to the definitions. Results of measurements are shown as graphical dependencies of rheologic parameters to the temperature. Temperature dependencies of vegetable oils dynamic and kinematic viscosity had decreasing exponential shape which is in accordance with Arrhenius equation and temperature dependencies of fluidity had an increasing exponential shape for both samples. Dependencies of samples density on temperature were characterized by decreasing linear function in measured temperature range. Similar results were obtained by other authors. From measured values can be seen that dynamic viscosity of olive oil is higher than viscosity of sunflower oil. This proportion is caused by different composition of oils.

Elucidation of Lubrication Mechanism of Vegetable Oils and Their Effective Application

Tribology Online, 2008

From the viewpoint of natural environmental requirement, the applications of biodegradable lubricants are growing. Most of vegetable oils are biodegradable and have good lubricating performance even at high contact pressure conditions in spite of their lower pressure-viscosity coefficient. In vegetable oils, however, the optimum suppression of oxidative degradation is required to improve the longevity of vegetable oils. Therefore, it is required to clarify the actual lubrication mechanism in vegetable oils with appropriate antioxidant additives. In this study, the tribological properties of four kinds of vegetable oils of different composition were evaluated in four-ball tests at different sliding speed conditions. As an antioxidant additive, α-tocopherol was used. The types of fatty acids in triglycerides appeared to control the lubricating performance through adsorbed film and friction polymer formation, depending on the operating conditions. Therefore, the paraffinic oils containing fatty acid were tested. It was shown that the influences of fatty acid types on lubricating performance were different depending on sliding speeds. These differences are discussed from the viewpoints of the role of friction polymer and oxidation of oils evaluated by FTIR analyses. Finally, effective application of various vegetable oils is discussed on the basis of relationship between tribological behaviors and operating conditions.

Study of Rheological Properties of Industrial Lubricants

Conference Papers in Science, 2014

The most important rheological parameter for lubricants is viscosity as it also affects the tribological properties like friction between interacting surfaces and wear. This research intends to study the relationship between viscosity and temperature at different shear rates for multiple grades of three different categories of lubricants used for different applications viz. L1: MG20W50 (engine oil), L2: SAE20W50 (engine oil), L3: MC20W50 (mineral engine oil), L4: EP90 (gear oil), and L5: DXTIII (steering fluid). Constant high dynamic viscosity, shear stress, and low compressibility at different temperatures in multigrade as well as single grade industrial oil will help to maintain the surface film over the period of time and hence the reduction in wear. The dynamic viscosity of these chosen samples has been measured experimentally in temperature range of 20 to 50°C. The measurements have been extended to observe the dependence of shear rate, time, and temperature on the dynamic visc...