Rheological Properties of Two Unvulcanized Rubber Compounds as Determined on an Extrusion and a Rotational Viscometer

1964 ◽  
Vol 37 (2) ◽  
pp. 491-502
Author(s):  
F. E. Devine ◽  
J. A. Ross
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Extrusion Pressure ◽  
Rheological Parameters ◽  
Shear Stresses ◽  
Extrude Material ◽  
Rotational Viscometer ◽  
Shear Rates ◽  
Rubber Compounds

Abstract The viscometer manufactured by A. Macklow-Smith Ltd., which operates at constant rate of extrusion, is a capillary instrument designed for the determination of flow properties of plastics. The instrument has been used for examining the rheological characteristics of rubber compounds and it has been possible to derive the shear stresses required to extrude material at various shear rates between 2 and 1050 sec−1. The general method of operation of the instrument for this purpose is discussed including the determination of preheat time before extrusion and the aspect of incipient vulcanization in the viscometer during extrusion. The effects of various lengths and diameters of dies on rheological parameters and entrance effects are discussed. An important aspect of the work is the observation of a piston height effect in the extruder barrel. Two different compounded polymers have been examined and in one case, the extrusion pressure was found to decrease with piston height whilst in the other highly elastic material, it was found that as the piston descended, the extrusion pressure increased to an equilibrium value. The importance of this effect in obtaining consistent shear stress data is discussed. Results of the work have been expressed in terms of apparent viscosity and also in terms of the parameters which describe a power law relating shear stress and shear rate within the capillary die. Rheological data have been obtained at various temperatures within the range of processing temperatures of the compounds. The effects on rheological properties of mastication and relaxation time after mastication have been examined. Results have been compared with figures obtained on conventional laboratory viscometers such as the Mooney Plastometer and the Wallace Rapid Plastimeter. A biconical, rotational viscometer has also been used at the lower range of shear rates and the results are compared with those obtained from the extrusion viscometer.

Rheological Properties of Aircraft Grease Containing Nano-Additives

2009 ◽  
Vol 419-420 ◽  
pp. 53-56
Author(s):  
Bao Yu Song ◽  
Qing Xiang Yang ◽  
Feng Zhang ◽  
Dai Zhong Su
Keyword(s):  
Rheological Properties ◽  
Apparent Viscosity ◽  
Shear Thinning ◽  
Nano Particles ◽  
Rheological Parameters ◽  
Nanoparticle Concentration ◽  
Rotational Viscometer ◽  
Shear Rates ◽  
The One ◽  
The Given

The apparent viscosity of aircraft grease with different nano-particles content, temperature and shear rates were studied using a rotational viscometer. The rheological properties of two types of aircraft grease, the basic grease and the one with nano-particles additives, were investigated using a rheometer. The results indicated that the apparent viscosity increases with the increase of nanoparticle concentration with the given ratio of nano-particles added. It was also found that the grease with and without the nano-particles both have yield stresses and clear shear-thinning properties. The shear-thinning phenomenon of the grease containing nano-particles is more evident than that of the basic grease. The experimental results also reveal that the rheological characteristics of both types of grease fall in Herschel-Bulkley class, and the nano-particles have a significant influence on the rheological parameters. At the end, the rheology mechanism was discussed based on the entanglement and orientation theories.

scholarly journals Effect of Temperature and Used Ingredients on Rheological Parameters of Pancake Dough

2013 ◽  
Vol 16 (3) ◽  
pp. 63-66
Author(s):  
Peter Hlaváč ◽  
Monika Božiková
Keyword(s):  
Rheological Properties ◽  
Dynamic Viscosity ◽  
Kinematic Viscosity ◽  
Fat Content ◽  
Effect Of Temperature ◽  
Rheological Parameters ◽  
Rotational Viscometer ◽  
Two Samples ◽  
Dynamic And Kinematic Viscosity ◽  
Temperature Dynamic

Abstract This paper presents the selected rheological properties of pancake dough such as dynamic and kinematic viscosity and fluidity. The effect of used ingredients and temperature on rheological properties is investigated. Measurements were performed on three pancake dough samples. In two samples, there was used milk with a different fat content, and in the third sample, all ingredients were in a powder state. A digital rotational viscometer Anton Paar DV-3P was used for measuring the rheological properties. The principle of viscometer measurement is based on the dependence of sample resistance to probe rotation. Results of measurements are shown as graphical dependencies of rheological parameters on temperature. Exponential functions were used to express the dependencies of all rheological parameters on temperature. Dynamic and kinematic viscosity decreased, and fluidity increased with temperature. The highest values of dynamic viscosity were obtained for pancake dough from powder ingredients. A higher fat content of used milk caused higher values of dynamic viscosity.

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.

scholarly journals RESEARCH OF RHEOLOGICAL PROPERTIES OF MEDICINAL SYRUP FOR ORAL USE

2020 ◽  
Vol 73 (4) ◽  
pp. 696-699
Author(s):  
Lena L. Davtian ◽  
Galyna P. Kukhtenko ◽  
Alona S. Voronkina ◽  
Viktoria V. Kudria
Keyword(s):  
Rheological Properties ◽  
Mechanical Stability ◽  
Rheological Parameters ◽  
Dynamic Flow ◽  
Shear Rates ◽  
Coaxial Cylinders ◽  
Low Degree ◽  
Newtonian Type ◽  
Rotary Viscometer

The aim of the present research was to investigate the rheological properties of the medicinal syrup for oral administration with glucosamine hydrochloride and levocarnitine. Matherials and methods: Coefficient of the dynamic flow (at shear rates of 3,49 and 10,3 s -1, as well as at shear rates of 27.2 and 149.0 s-1), mechanical stability, the index of destruction and restoration were studied. The rheological (structural-mechanical) properties of the samples were determined using a Rheolab QC rotary viscometer (AntonPaar, Austria) with coaxial cylinders CC27 / S-SN29766. The rheological parameters were studied at the temperature 20±0,5 °С. Results: It is established that the syrup has weakly expressed plastic viscous and thixotropic properties (the hysteresis area for the syrupis 1710.19 Pas/s). Such results characterize the system as a reopex. Conclusions: The results of the study enables classification of the research object as system with a low degree of fluidity. Such dependence is typical for systems of the Newtonian type of flow and characterizes the syrup under investigation as a weakly structured disperse system.

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.

scholarly journals Determination of Rheological Parameters from Measurements on a Viscometer with Coaxial Cylinders – Choice of the Reference Radius

10.14311/892 ◽  
2006 ◽  
Vol 46 (6) ◽  
Author(s):  
F. Rieger
Keyword(s):  
Experimental Data ◽  
Power Law ◽  
Rheological Behavior ◽  
Experimental Results ◽  
Rheological Parameters ◽  
Concentrated Suspensions ◽  
Rotational Viscometer ◽  
Coaxial Cylinders

Knowledge about rheological behavior is necessary in engineering calculations for equipment used for processing concentrated suspensions and polymers. Power-law and Bingham models are often used for evaluating the experimental data. This paper proposes the reference radius to which experimental results obtained by measurements on a rotational viscometer with coaxial cylinders should be related. 

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.

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.

THE EFFECT OF THE TYPE OF WALL MATERIAL AND GREASE COMPOSITION PAIRING ON SHEAR STRESSES IN BOUNDARY LAYER

Tribologia ◽  
2019 ◽  
Vol 284 (2) ◽  
pp. 27-36
Author(s):  
Ryszard Czarny
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Rheological Properties ◽  
Wall Material ◽  
Shear Stresses ◽  
Lubrication System ◽  
Test Results ◽  
Lubricant Composition ◽  
Grease Composition ◽  
System Knowledge

The paper presents the results of research on the influence of fillers introduced into plastic greases on the rheological properties of the boundary layer of the resultant lubricant compositions. The fillers were PTFE and MoS2 powders. They are added to lubricants to improve their tribological properties; however, these fillers also affect the rheological properties of the composition. This affects the change of the shear stress value in the lubricant during its flow in the lubrication system. Knowledge of this value, especially during the flow of the lubricant composition in the boundary layer, has a significant impact on the operation of automated central lubrication systems in which these compositions can be used. Measurements were carried out by means of a rotary rheometer (Rheotest 2.1). Tests were performed on lithium and bentonite greases (without additives) as well as compositions of these greases containing various percentage of the fillers mentioned above. Test results showed that both the type of grease and the type of filler introduced into this grease affect the rheological properties in the boundary layer of the produced lubricating compositions.

scholarly journals CRITERIONAL FEATURES OF STRUCTURAL CHARACTERISTICS OF FINE TEXTILE MEAT

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
М. П. Сичевський ◽  
Л Войцехівська ◽  
К В Копилова ◽  
C Б Вербицький ◽  
Ю І Охріменко
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Maximum Shear Stress ◽  
Fat Content ◽  
Plastic Viscosity ◽  
Poultry Meat ◽  
Rheological Parameters ◽  
Limit Values ◽  
Mechanically Separated Meat ◽  
Minced Meat

Poultry meat mechanically separated from broiler carcasses and compared with minced meat from manual deboning was studied. It has been found that an increase in the free moisture content of mechanically separated meat by 10-15% causes a reduction in shear characteristics by almost 2 times. The shear stress values ​​in hand-rolled meat samples were, on average, 1.3 times higher than in physico-chemically similar samples of mechanically separated meat. The samples of hand-rolled meat differed by 1.4 times the values ​​of plastic viscosity, as well as larger, on average 1.5 times, the values ​​of the coefficient of consistency. A set of rheological parameters and their limit values, close to the characteristics of minced meat from manual deboning, namely: the maximum shear stress (penetration) - from 1.9 kPa to 2.2 kPa; plastic viscosity - from 33 Pa • s to 45 Pa • s; coefficient of consistency - from 1.4 to 1.7. It has been established that the most important factors influencing the difference between the rheological parameters of mechanically separated meat and hand-rolled meat are the fat content and the degree of grinding. The reduction of fat content, processing pressure, as well as the speed of grinding of raw materials allows to bring the rheological characteristics of mechanically separated meat to the characteristics of manual deboning meat. The nature of the change in the rheological properties of meat mechanically separated over time is revealed: during the first stage (lasts about 2-3 hours) the structure remains unchanged, the second stage is the period of growth of all indicators to the maximum value, this is the period of critical aging. Further aging (third period) is characterized by a decrease in the numerical values ​​of all indicators, due to a decrease in the strength of the structure under the action of a complex of microbiological and biochemical processes. The study of the rheological properties of mechanically separated meat of broiler chickens and the comparison of the obtained indicators with the corresponding characteristics of minced meat formed by mincing hand-rolled meat, gave grounds for concluding on the possibility and expediency of mechanically separated meat in meat products.

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