scholarly journals The influence of base oil type on the rheological properties of ecological lubricating greases

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (2) ◽  
pp. 127-135
Author(s):  
Rafał Kozdrach ◽  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Measurement Data ◽  
Measuring System ◽  
Rheological Parameters ◽  
Flow Curves ◽  
Lubricating Grease ◽  
Dispersion Phase ◽  
Base Oil

The article presents the results of research on the influence the type of base oil in lubricating compositions has on the rheological parameters of selected lubricants. Vegetable, mineral, and synthetic dispersion phases were used to produce lubricating greases. The modified amorphous silica was used as the dispersed phase. However, as a modifying additive was used a substance containing the antioxidants, corrosion inhibitors, and EP/AW additives. The experiments on rheological properties were carried out using a Physica MCR 101 rotational rheometer (manufactured by Anton Paar), equipped with a diffusion air bearing and connected to a pneumatic supply – an oil-free Jun-Air compressor and air drying block. The device is equipped with a Peltier system for temperature control in the range of –20°C to 200°C and an external thermostatic VISCOTHERM V2 system, working in the temperature range of –20°C to 200°C. The rheometer control and measurement data analysis were performed using Rheoplus software. The tests were carried out using a cone-plate measuring system with a shear rate range of 0.01–100 s-1 at 20°C for lubricating compositions prepared on various oil bases. To evaluate the value of rheological parameters, the results of tests of the dependence between shear stress and shear rate (flow curves) were used. For the theoretical determined on the flow curves, the following rheological models were used: Bingham, Herschel–Bulkley, Casson, and Tscheuschner. The values of the shear stress (yield point) in depending on the type of dispersion phase has changed. This proves that the use of a base oil with the appropriate functional properties does not weaken, but reinforces the spatial structure of a lubricating grease. It has an important meaning when selecting construction parameters when designing a central lubrication system with grease made from a vegetable oil base (Abyssinian oil). The rheological properties of the lubricating grease are influenced by the type of base oil and thickener, any additives in the grease, the production technology of the grease, and the conditions in which it is used. The tests revealed an important influence of the base oil on the rheological parameters that describe the behaviour of lubricating compositions subjected to stresses and strains in a lubricating system.

A Rheological Study of Lemon Curd Made of Frozen-thawed Liquid Egg Yolk

2021 ◽  
pp. 7-11
Author(s):  
Karina I. Hidas ◽  
◽  
Anna Visy ◽  
Ildikó Cs. Nyulas-Zeke ◽  
László Friedrich ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Frozen Storage ◽  
Egg Yolk ◽  
Egg White ◽  
Lemon Juice ◽  
Hot Water ◽  
Rheological Parameters ◽  
Flow Curves ◽  
Rheological Study

In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by preparing lemon curd samples. Therefore, LEY frozen at-18°C was used to make lemon curd samples. LEY was stored for 90 days at -18°C and it was thawed with two different methods (in 2 hours, 35°C and in 24 hours, 5°C) on measurement days (day 1, 7, 14, 30, 60 and 90). After thawing of LEY samples, lemon curd samples were made by adding liquid egg white, butter, lemon juice and sugar. Ingredients were mixed by constant whisking over the steam of hot water. After that, butter was also added to the cream and it was cooled to 20°C. Rheological parameters of the lemon curd samples were examined with rotational rheometer. Shear stress data were recorded by increasing, than by decreasing shear rate values in the range of 10-1000 1/s. Herschel-Bulkley model was fitted to the flow curves of decreasing shear rate. Based on our measurements, we found that the thawing method of frozen liquid egg yolk does not affect the rheological properties of lemon curd made of them, but the length of the frozen storage does.

Rheological properties of cholesteric liquid crystals as lubricant additives

2019 ◽  
Vol 33 (05) ◽  
pp. 1950014 ◽  
Author(s):  
A. Bindu Madhavi ◽  
S. Sreehari Sastry
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Loss Modulus ◽  
Flow Behavior ◽  
Lubricant Additives ◽  
Rheological Parameters ◽  
Practical Applications ◽  
Phase Transition Temperatures ◽  
Frequency Independent ◽  
Temperature Shear

Rheological properties of Cholesteryl n-valerate, Cholesteryl decanoate and Cholesteryl myristate which are esters of cholesterol have been studied. Phase transition temperatures and rheological parameters such as viscosity, elastic modulus G[Formula: see text], loss modulus G[Formula: see text] as functions of temperature, shear rate and time are investigated. In frequency sweep test, a higher transition crossover region has occurred for Cholesteryl myristate, whereas for Cholesteryl n-valerate a frequency-independent plateau prevailed for both the moduli. The occurrence of blue phase in Cholesteryl decanoate during temperature sweep measurements is an indication for the rheological support. The results for steady state have informed that cholesteric esters are having non-Newtonian flow behavior in their respective cholesteric phases. The power-law model has explained well the shear rate dependence of shear stress. A few practical applications of these esters as lubricant additives are discussed, too.

The Rheological Characterization of the Writing Performance of Carbon Black Gel Ink

2009 ◽  
Vol 66 ◽  
pp. 139-142 ◽  
Author(s):  
Ji Jun Qian ◽  
Ai Ping Chen ◽  
Zhong Xin Liu ◽  
Chun Zhong Li
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Carbon Black ◽  
Rheological Parameters ◽  
Rheological Characterization ◽  
Writing Performance ◽  
Strong Shear ◽  
The Common ◽  
The Relationship

The rheological properties of carbon black gel ink were investigated by measurement the relationship between shear stress and shear rate. The fitting to the common rheological curve of gel ink with Hersegel-Bulkley equation was introduced. And the rheological parameters used to characterize the writing properties of gel ink were proposed. The results indicated that the gel ink system possessed strong shear-thinning ability. And the writing performance of the gel ink could be characterized with rheological parameters comprehensively.

Influences of Micropowder Gradation on Rheological Properties of Cement-Based Composite Pastes

2007 ◽  
Vol 353-358 ◽  
pp. 1398-1401
Author(s):  
Jian Qing Gong ◽  
Han Ning Xiao ◽  
Zheng Yu Huang ◽  
Jiu Su Li ◽  
Jing Nie ◽  
...  
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Packing Density ◽  
High Performance ◽  
High Performance Concrete ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Ultra High Performance Concrete ◽  
Cement Pastes ◽  
Compressible Packing Model

The rheological parameters of cement pastes were investigated by varying the type and content of micropowders and the ratio of water to binder. Compressible packing model was used to calculate the packing density and to evaluate the influence of micropowders gradation on the rheological properties of fresh cement pastes. Results indicate that the higher the packing density is, the lower the yielding shear stress and plastic viscosity will be. When the ratio of water to binder is less than 0.20, the cement paste with 15% UFA and 15% SF has highest packing density and lowest yielding shear stress and plastic viscosity, which is beneficial to the workability of ultra-high performance concrete.

Effect of Organic Bentonite on Rheological Properties of Paper Coating

2011 ◽  
Vol 197-198 ◽  
pp. 383-386
Author(s):  
Hu Nan Liang ◽  
Zhu Long ◽  
Shu Hui Yang
Keyword(s):  
Shear Stress ◽  
Reaction Time ◽  
Rheological Properties ◽  
Rheological Behavior ◽  
Paper Coating ◽  
Flow Curves ◽  
Pseudoplastic Fluid ◽  
Sodium Bentonite ◽  
Cross Model ◽  
Organic Bentonite

Effect of organic bentonite on rheological behavior of paper coating was studied. Organic bentonite was prepared by treating sodium bentonite with dimethyl diallyl ammonium chloride (DADMAC) at the following conditions: DADMAC 20%, reaction time 3h, reaction temperature 80°C and pH 9. The results showed that shear stress and voscosity of coating enhance with increasing the amount of organic bentonite. In this testing, all of flow curves fitted Cross model very much, and rheologiclal properties showed the pseudoplastic fluid, characterized as obvious shear thinning .The bentonite modified with DADMAC could promote the rheological behavior of coating.

Preparation of Magnetorheological Fluid and Study on Its Rheological Properties

2014 ◽  
Vol 13 (02) ◽  
pp. 1450009 ◽  
Author(s):  
Shreedhar Kolekar
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Magnetorheological Fluid ◽  
Magnetic Flux Density ◽  
Iron Loading ◽  
Iron Particles ◽  
Mr Fluid ◽  
Carrier Fluid ◽  
System Type

The present paper focuses on preparation and process of the magnetorheological (MR) fluid whose carrier fluid is silicone-based oil and its additive is the commercial grease with different concentration of iron particles. General properties of MR fluid are discussed and rheological properties like shear rate, shear stress, viscosity of MR fluid can be found by using cone-and-plate sensor system-type rheometer. The result shows that shear stress as a function of magnetic flux density and viscosity does not strictly scale with iron loading.

scholarly journals PROCESSING ADDITIVES AND RHEOLOGICAL PROPERTIES OF MOLDED PHENOLIC PLASTICS

2019 ◽  
Vol 14 (1) ◽  
pp. 90-96
Author(s):  
P. V. Surikov ◽  
N. L. Shembel ◽  
A. A. Yurkin ◽  
A. V. Petrogradsky ◽  
V. D. Sevruk ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Phenolic Resin ◽  
Volume Fraction ◽  
Slip Flow ◽  
Capillary Wall ◽  
Flow Curves ◽  
Flow Through ◽  
Capillary Viscosimetry ◽  
Stress Flow

By the method of capillary viscosimetry, the melt flow curves of the molded phenolic resin and its compositions with lubricant, plasticizer and their mixture were obtained. It was shown that the size (diameter) of the capillary channel influences the dependence of the effective shear rate on the shear stress (flow curves) of the studied compositions. Such rheological behavior of the compositions during flow is associated with the effect of sliding along the surface of the capillary wall. According to the Mooney method, the dependences of the effective shear rate at given values of shear stress on the reciprocal of the capillary radius are plotted. The function of the slip velocity on the shear stress on the capillary wall is characterized in terms of the slip coefficient, which relates the shear stress on the capillary wall to the velocity of the composition along it. For the studied compositions, the total flow through the capillary was divided into volume fractions, one of which is associated with a shear flow; the other is determined by the slip effect. It has been shown that the introduction of both a lubricant and a plasticizer into the composition leads to an increase in the fluidity of the compositions. At the same time, adding of lubricant increases the volume fraction of the slip flow. The greatest effect of increasing the fluidity of the composition gives the use of complex modifying additives containing both lubricant and plasticizer.

scholarly journals Influence of plasma on the physical properties of ointments with quercetin

2017 ◽  
Vol 67 (4) ◽  
pp. 569-578
Author(s):  
Beata Szulc-Musioł ◽  
Barbara Dolińska ◽  
Justyna Kołodziejska ◽  
Florian Ryszka
Keyword(s):  
Shear Stress ◽  
Physical Properties ◽  
Rheological Properties ◽  
Rheological Parameters ◽  
Organoleptic Properties ◽  
Independent Variables ◽  
Newtonian Systems ◽  
Two Independent Variables

Abstract Effects of two independent variables - the content of quercetin (0 or 1 or 1.5 or 5 %) and the content of plasma (0 or 2 or 4 or 6 %) - on the organoleptic properties and rheological parameters of model formulations prepared on an amphiphilic base were estimated. The consistency of all ointments was uniform, and the content of quercetin and plasma lay within the predefined range. Tested ointments are non-Newtonian systems. The content of quercetin and plasma was found to have a significant effect on the rheological properties of the ointments. An increase in the content of plasma in ointments was accompanied by a significant increase in their hardness, viscosity and shear stress and a reduction of their spreadability. The best rheological properties were shown by formulation F-3, containing 1.5 % of quercetin and 2 % of plasma.

Yield Stress of Emulsions and Suspensions as Measured in Steady Shearing and in Oscillations

2008 ◽  
Vol 18 (4) ◽  
pp. 44790-1-44790-8 ◽  
Author(s):  
I. Masalova ◽  
A.Ya. Malkin ◽  
R. Foudazi
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Flow Curves ◽  
Dynamic Yield Stress ◽  
Shear Rates ◽  
Meaningful Material ◽  
Dynamic Yield ◽  
Steady Shearing ◽  
Concentrated Emulsions

Abstract The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were determined in two ways. In one case, steady shear experiments were performed over a range of incrementally decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley model being fitted to obtain values. In the second case, oscillatory amplitude sweeps were performed at three frequencies, and the “dynamic yield stress” was defined as the stress at which deviation from linearity occurred; this procedure has often been used to determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency dependent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.

RELATION BETWEEN SHEAR STRESS AND SHEARING TIME IN SELECTED LUBRICANT COMPOSITIONS

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 25-33 ◽  
Author(s):  
Ryszard CZARNY
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Rheological Properties ◽  
Tribological Properties ◽  
Shear Stresses ◽  
Test Results ◽  
Molybdenum Disulphide ◽  
Lithium Grease ◽  
Lubricant Composition ◽  
Rate Test

The paper presents the results of studies of the influence of fillers introduced into lubricating greases on changes in values of shear stresses in resulting lubricant compositions. These fillers were powders of graphite, molybdenum disulphide, and PTFE. They are added to grease to improve their tribological properties. They also impact the rheological properties of lubricating compositions, especially on the course of the shear stress, whose value decreases with the duration of the flow of these compositions. Knowledge of changes in the value of this stress is essential in designing central lubrication systems in which these compositions may be used. Tests were performed on lithium grease without fillers as well as on a composition of this grease with the fillers mentioned above. Measurements were carried out using a Rheotest 2.1 rheometer by changing the shearing time at selected gradients of shear rate. Test results have shown that both the kind of filler and the shearing time have an impact on the value of shear stress in the tested lubricant composition.

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