scholarly journals New Considerations on the Determination of the Apparent Shear Viscosity of Polymer Melt with Micro Capillary Dies

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4451
Author(s):  
Wangqing Wu ◽  
Ke Zeng ◽  
Baishun Zhao ◽  
Fengnan Duan ◽  
Fengze Jiang
Keyword(s):  
Shear Viscosity ◽  
Compaction Pressure ◽  
Experimental Studies ◽  
Polymer Melt ◽  
Rheological Measurement ◽  
Shear Rates ◽  
Micro Scale ◽  
Viscosity Determination ◽  
Main Factor

Capillary rheometers have been widely used for the rheological measurement of polymer melts. However, when micro capillary dies are used, the results are usually neither accurate nor consistent, even under the same measurement conditions. In this work, theoretical modeling and experimental studies were conducted for a more profound understanding of the mechanism by which the initial and boundary conditions influence the inaccuracy in the apparent shear viscosity determination with micro capillary dies (diameters: 500 μm, 200 μm, 100 μm). The results indicate that the amount of polymer initially in the barrel, the pre-compaction pressure and the capillary die diameter have a significant influence on the development of the micro scale inlet pressure, which directly determines the accuracy of the measurement at low and medium shear rates. The varying melt compressibility was confirmed to be the main factor directly related to the inaccuracy in the micro scale apparent shear viscosity determination. It is suggested that measures such as reducing the amount of polymer initially in the barrel and increasing the pre-compaction pressure could be used to reduce the measurement inaccuracy.

Viscous Dissipation of Polymer Melt in Micro Channels and Macro Channels

2014 ◽  
Vol 609-610 ◽  
pp. 521-525
Author(s):  
Bin Xu ◽  
Xiao Yu An ◽  
Liang Chao Li ◽  
Guang Ming Li
Keyword(s):  
Shear Rate ◽  
Viscous Dissipation ◽  
Unit Length ◽  
Experimental Studies ◽  
Polymer Melt ◽  
Characteristic Size ◽  
Micro Scale ◽  
Micro Channels ◽  
Macro Scale ◽  
The Difference

Viscous dissipation is the key factor impacting flowing characteristics of polymer melt. In order to study the difference between micro scale and macro scale, experimental studies of viscous dissipation at various shear rate were investigated with several polymers, including PMMA and HDPE, at different temperature when melts flow through 1000μm,500μm,350μm diameter channels of identical aspects ratio in the paper. The results indicate that the temperature rises caused by viscous dissipation increase with increasing shear rate and the temperature rise for some shear rate decreases with increasing melts temperature. The temperature rises decrease significantly with the reduction of the characteristic size of micro channel at the same shear rate. However, the average temperature rises per unit length increase when the character size of channel decreases. This indicates the shear friction gradually increases with the decrease of channel characteristic size. Therefore polymer melt viscous dissipation effects of micro scale dimensions are different from that of macro-scale dimensions.

SHEAR VISCOSITY OF STRONGLY-COUPLED TWO-DIMENSIONAL YUKAWA LIQUIDS: EXPERIMENT AND MODELING

2007 ◽  
Vol 21 (21) ◽  
pp. 1357-1376 ◽  
Author(s):  
Z. DONKÓ ◽  
P. HARTMANN ◽  
J. GOREE
Keyword(s):  
Shear Viscosity ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Simulation Studies ◽  
Strongly Coupled ◽  
Shear Rates ◽  
High Shear Rates ◽  
Wide Range ◽  
Computer Simulation Studies

This paper reviews experimental and modeling efforts aimed at the determination of the shear viscosity of strongly-coupled Yukawa liquids. After briefly reviewing prior work on three-dimensional (3D) systems, recent experimental and computer simulation studies of two-dimensional (2D) settings are presented in detail. In the experiments two counterpropagating laser beams were used to perturb a dusty plasma monolayer and monitoring of the velocity field reconstructed from particle trajectories allowed the determination of the shear viscosity with the aid of an analytical model. Subsequent computer simulations based on the molecular dynamics approach resulted in velocity profiles which are in very good agreement with the experimental ones. Further simulation studies of idealized 2D Yukawa liquids (in which gas friction is neglected) gave results for the shear viscosity over a wide range of system parameters and demonstrated the existence of the shear thinning effect (non-Newtonian behavior) of the liquid at high shear rates.

Spray Pattern and Droplet Size Analyses for High-Shear Viscosity Determination of Aqueous Suspension Corticosteroid Nasal Sprays

2008 ◽  
Vol 34 (9) ◽  
pp. 923-929 ◽  
Author(s):  
Justin Pennington ◽  
Preetanshu Pandey ◽  
Henry Tat ◽  
Jennifer Willson ◽  
Brent Donovan
Keyword(s):  
Droplet Size ◽  
Shear Viscosity ◽  
Aqueous Suspension ◽  
High Shear ◽  
Spray Pattern ◽  
Nasal Sprays ◽  
Viscosity Determination

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Energetic properties of peat saturated with petroleum products

2020 ◽  
Vol 13 (2) ◽  
pp. 105-109
Author(s):  
E. S. Dremicheva
Keyword(s):  
Crude Oil ◽  
Diesel Fuel ◽  
Energy Use ◽  
Experimental Studies ◽  
Calorific Value ◽  
Petroleum Products ◽  
Ash Content ◽  
Motor Oil ◽  
Initial Sample

This paper presents a method of sorption using peat for elimination of emergency spills of crude oil and petroleum products and the possibility of energy use of oil-saturated peat. The results of assessment of the sorbent capacity of peat are presented, with waste motor oil and diesel fuel chosen as petroleum products. Natural peat has been found to possess sorption properties in relation to petroleum products. The sorbent capacity of peat can be observed from the first minutes of contact with motor oil and diesel fuel, and significantly depends on their viscosity. For the evaluation of thermal properties of peat saturated with petroleum products, experimental studies have been conducted on determination of moisture and ash content of as-fired fuel. It is shown that adsorbed oil increases the moisture and ash content of peat in comparison with the initial sample. Therefore, when intended for energy use, peat saturated with petroleum products is to be subjected to additional drying. Simulation of net calorific value has been performed based on the calorific values of peat and petroleum products with different ratios of petroleum product content in peat and for a saturated peat sample. The obtained results are compared with those of experiments conducted in a calorimetric bomb and recalculated for net calorific value. A satisfactory discrepancy is obtained, which amounts to about 12%. Options have been considered providing for combustion of saturated peat as fuel (burnt per se and combined with a solid fuel) and processing it to produce liquid, gaseous and solid fuels. Peat can be used to solve environmental problems of elimination of emergency spills of crude oil and petroleum products and as an additional resource in solving the problem of finding affordable energy.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

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