Shear degradation resistance of star poly(ethyleneimine) - polyacrylamides during elongational flow

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Ming Duan ◽  
Shenwen Fang ◽  
Liehui Zhang ◽  
Fuxiao Wang ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Shear Rate ◽  
Aqueous Solutions ◽  
Relative Viscosity ◽  
Reduction Rate ◽  
Elongational Flow ◽  
Exponential Dependence ◽  
Distilled Water ◽  
Shear Stability ◽  
Low Viscosity ◽  
Shear Degradation

AbstractAn experimental study of the flow-induced scission behaviour of four star hydrolyzed polyacrylamides (HPMA) with different arms during planar elongational flow in a cross-slot flow cell is described. The results showed that the shear stability of linear HPAM in distilled water was not essentially different from star HPAM. Polymer scission was not observed in either system in a shear rate range from 20,000 to 100,000s-1, which can be attributed to the strong polyelectrolyte behaviour of HPAM in distilled water. However, at the same shear rate, the star HPAMs exhibited superior shear stability in comparison to the linear HPAMs in aqueous solutions containing NaCl (CNaCl=0.2-1.0%wt) and, in particular, the initial reduction rate of relative viscosity (R) decreased with the degree of branching of the HPAMs. In addition, it was found that the R of five HPAMs in NaCl aqueous solutions exhibited an exponential dependence on shear rate, in which the coefficient C1 can be used to quantitatively evaluate shear stability. In star HPAM NaCl aqueous solutions, the increase of R with shear rate is very likely due to the decrease of the hydrodynamic radius (Rh) of these HPAMs, while the increase of R with NaCl concentrations can be attributed to the relatively low viscosity of these polymers at high NaCl concentrations.

Shear Stability of EOR Polymers

SPE Journal ◽  
2012 ◽  
Vol 17 (02) ◽  
pp. 335-339 ◽  
Author(s):  
A.. Zaitoun ◽  
P.. Makakou ◽  
N.. Blin ◽  
R.S.. S. Al-Maamari ◽  
A.R.. R. Al-Hashmi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Shear Rate ◽  
High Molecular Weight ◽  
Degradation Rate ◽  
Capillary Tube ◽  
Mobility Control ◽  
Chain Flexibility ◽  
Shear Stability ◽  
High Molecular Weight Polymers ◽  
Shear Degradation

Summary An experimental study of shear stability of several high-molecular-weight polymers used as mobility-control agents in EOR projects has been performed in well-controlled conditions. The shearing device was made of a capillary tube with an internal diameter (ID) of 125 μm, through which polymer solution was injected at a controlled rate. The setup enables a precise measurement of the shear rate to which the polymer macromolecule is submitted. The degradation rate was measured by the viscosity loss induced by the passage into the capillary tube. The shear rate was gradually increased up to 106 sec–1 while checking degradation rate at each stage. Different commercial EOR polymer products were submitted to the test with polyacrylamide backbone and different substitution monomer groups. All macromolecules behave as flexible coils in solution. The parameters investigated were Molecular weight (between 6 and 20×106)Nature of substitution group (acrylate, ATBS/sulfonate, nVP/ vinyl-pyrrolidone)Salinity Polymer shear degradation increases with molecular weight and salinity, but decreases with the presence of acrylate, ATBS, and nVP. All results can be interpreted in terms of chain flexibility. The highly flexible polyacrylamide homopolymer is the most sensitive to shear degradation. Introduction of acrylate groups in the polymer chain induces some stability because of the rigidity provided by charge repulsion, which vanishes in the presence of high salinity because of the screening of acrylate negative charges. ATBS and VP groups, which are larger in size, provide significant chain rigidity, and thus better shear stability. It is also shown that some very-high-molecular-weight polymers, after passing the shearing device, attain a final viscosity lower than lower-molecular-weight products with the same chemical composition. This factor has to be taken into account in the final choice of a polymer for a given field application. As a comparison, although less popular today than 2 decades ago, xanthan gum (XG), which behaves like a semirigid rod, is shown to be much less sensitive to the shear-degradation test than the coiled polyacrylamides (Sorbie 1991).

STUDIES ON CARRAGEENIN: THE EFFECT OF SHEAR RATE ON VISCOSITY

1955 ◽  
Vol 33 (5) ◽  
pp. 895-903 ◽  
Author(s):  
C. R. Masson ◽  
D. A. I. Goring
Keyword(s):  
Molecular Weight ◽  
Shear Rate ◽  
Aqueous Solutions ◽  
High Molecular Weight ◽  
Interaction Coefficient ◽  
Distilled Water ◽  
Zero Rate ◽  
Ionic Impurities

The viscosity of aqueous solutions of carrageenin of high molecular weight was markedly dependent on the rate of shear. The shear-dependence increased with decrease in the concentration of added electrolyte. Because of curvature, extrapolation of [η] to zero rate of shear was not possible. The Huggins interaction coefficient, k′, increased with decrease in rate of shear; k′ also increased with increase in concentration of added electrolyte. In water, maxima of ηsp/c were observed at concentrations of carrageenin equivalent to the ionic impurities in the distilled water used. At higher concentrations the data fitted the Fuoss equation at rates of shear of 200 and 100 sec.−1 but not below 100 sec.−1 The constants A and D both increased with decrease in rate of shear.

Penetration Dynamics of Solid Particles into Liquids High-Speed Experimental Results and Modelling

2005 ◽  
Vol 473-474 ◽  
pp. 429-434 ◽  
Author(s):  
Olga Verezub ◽  
György Kaptay ◽  
Tomiharu Matsushita ◽  
Kusuhiro Mukai
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Aqueous Solutions ◽  
Particle Velocity ◽  
Weber Number ◽  
High Speed ◽  
Solid Particles ◽  
Bulk Liquid ◽  
Distilled Water ◽  
Critical Weber Number

Penetration of model solid particles (polymer, teflon, nylon, alumina) into transparent model liquids (distilled water and aqueous solutions of KI) were recorded by a high speed (500 frames per second) camera, while the particles were dropped from different heights vertically on the still surface of the liquids. In all cases a cavity has been found to form behind the solid particle, penetrating into the liquid. For each particle/liquid combination the critical dropping height has been measured, above which the particle was able to penetrate into the bulk liquid. Based on this, the critical impact particle velocity, and also the critical Weber number of penetration have been established. The critical Weber number of penetration was modelled as a function of the contact angle, particle size and the ratio of the density of solid particles to the density of the liquid.

Flow Behaviors of High Acyl Gellan Aqueous Solutions as Affected by Temperature, and Calcium and Gellan Concentrations

2008 ◽  
Vol 4 (5) ◽  
Author(s):  
Yiqun Huang ◽  
Pawan Singh Takhar ◽  
Juming Tang ◽  
Barry G Swanson
Keyword(s):  
Shear Rate ◽  
Aqueous Solutions ◽  
Apparent Viscosity ◽  
Flow Resistance ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Influence Of Temperature ◽  
Rheological Behaviors ◽  
Low Concentrations ◽  
Influence Of Temperature On

Rheological behaviors of high acyl (HA) gellan are not well understood partially because of its relatively late commercialization compared to low acyl gellan. The objective of this study was to investigate the effect of temperature (5-30 °C), calcium (0, 1 and 10 mM) and gellan concentrations (0.0044-0.1000% w/v) on the flow behaviors of high acyl gellan aqueous solutions using rheological tests. Gellan solutions with 0 or 1 mM added Ca++ exhibited shear thinning behavior at gellan concentrations above 0.0125%. The influence of temperature on apparent viscosity (shear rate, 100 s-1) of gellan solutions can be described with an Arrhenius relationship. The apparent viscosity of gellan solution at low concentrations was more sensitive to temperature changes. The addition of Ca++ led to a decrease in flow resistance for a dilute gellan solution (<0.0125%), but an increased resistance for a relatively concentrated gellan solution (>0.0125%).

scholarly journals Acoustic, thermal and optical properties of organic based disodium tartrate salt

2021 ◽  
Vol 2 (1) ◽  
pp. 012-027
Author(s):  
M. Sathish ◽  
K. Venkataramanan ◽  
R. Padmanaban ◽  
Helan Ruth ◽  
K. Vadivel ◽  
...  
Keyword(s):  
Optical Properties ◽  
Aqueous Solutions ◽  
Internal Pressure ◽  
Ultrasonic Velocity ◽  
Relative Viscosity ◽  
Adiabatic Compressibility ◽  
Lower Percentage ◽  
Wada’S Constant ◽  
Different Temperatures ◽  
Solvent Molecules

In this work, acoustic, thermal, and optical properties were tested on the different concentrations of the Disodium Tartrate solutions. First, the viscosity studies were analyzed for the Disodium tartrate in the concentration range from 2% to 20% with different temperatures 303K, 308K, 313K, and 318K. It was noted that the relative viscosity and the activation energy of the prepared compound increase with increases in concentration and decreases with temperature increases. The properties like density and ultrasonic velocity are varied when increases the concentration of the aqueous solutions of Disodium Tartrate. In this study, the values of adiabatic compressibility show an inverse behavior when compared with ultrasonic velocity due to the interaction between solute and solvent molecules. Also observed that the inter-molecular free length is maximum for a lower percentage. The free volume for the compound is maximum at 2% and a minimum of 20%, since it reduces when the internal pressure increases. It was revealed that the classical absorption coefficient and relaxation time for Disodium Tartrate is minimum for lower percentage and minimum for a higher percentage. The interactions between the solute and solvent are confirmed through the property like specific Acoustical impedance. It was noted that the increase in internal pressure increases the concentration of the compound. The ion-solvent interaction was discussed by the relative association study, thus the values of relative association increases with an increase in concentration. The Rao’s and Wada’s constant increases linearly in aqueous solutions of Disodium Tartrate for the entire system.

Influence of shear rate and concentration ratio on viscous synergism. Application to xanthan—Iocust bean gum— NaCMC mixtures Influencia de la velocidad de cizalla y la relación de concentraciones en la sinergia viscosa. Aplicación a mezclas de xantana-garrofín-CMCNa

2000 ◽  
Vol 6 (5) ◽  
pp. 415-423 ◽  
Author(s):  
J. Pellicer ◽  
J. Delegido ◽  
J. Dolz ◽  
M. Dolz ◽  
M.J. Hernández ◽  
...  
Keyword(s):  
Shear Rate ◽  
Concentration Ratio ◽  
Xanthan Gum ◽  
Empirical Approach ◽  
Exponential Dependence ◽  
Locust Bean Gum ◽  
Synergistic Interactions ◽  
Fixed Proportion ◽  
Locust Bean ◽  
Definition Of

A method is described that allows the development of an empirical approach to quantify synergistic interactions and their variations with shear rate. The approach is based on the definition of a viscous synergism index, Iv. The method is applied to xanthan-locust bean gum gels, and an equation is developed for relating the synergism index to shear rate, γ, and the locust bean gum/xanthan gum concentration ratio, z. The value of at which that function has a maximum, IMV, is calculated. This value of z provided an estimation of the proportion of gums at which maximum synergism occurs. A decreasing exponential dependence of these IMV on γ is shown. The influence of the addition of a fixed proportion of a third gum (NaCMC) is also analyzed. The results obtained for the higher γ values are analogous to those of other authors.

scholarly journals Rheological Characteristics of Soluble Fibres during Chemically Simulated Digestion and their Suitability for Gastroparesis Patients

Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2479
Author(s):  
Harsha Suresh ◽  
Vincent Ho ◽  
Jerry Zhou
Keyword(s):  
Gastric Motility ◽  
Guar Gum ◽  
Relative Viscosity ◽  
Gum Arabic ◽  
Potential Candidate ◽  
Beta Glucan ◽  
Motility Disorders ◽  
Simulated Digestion ◽  
Balanced Diet ◽  
Low Viscosity

Dietary fibres are an integral part of a balanced diet. Consumption of a high-fibre diet confers many physiological and metabolic benefits. However, fibre is generally avoided by individuals with gastrointestinal motility disorders like gastroparesis due to increased likelihood of exacerbated symptoms. Low-viscosity soluble fibres have been identified as a possible source of fibre tolerable for these individuals. The aim of this study is to determine the rheological properties of 10 common commercially available soluble fibres in chemically simulated digestive conditions and evaluate their suitability for individuals with mild to moderate gastroparesis, a gastric motility disorder. Rheological testing under neutral condition (distilled water pH 7) and chemically simulated gastric digestion were evaluated to determine the yield point and relative viscosity of each fibre. Our results reveal two rheological categories of soluble fibres; pseudoplastic and dilatant. Simulated digestion was shown to significantly alter the yield-points of psyllium husk, iota-carrageenan, beta-glucan, apple-fibre pectin, and inulin. Gum Arabic and partially hydrolysed guar gum showed the lowest viscosities and were not affected under simulated digestion, characteristics that make them potential candidate fibres for patients with gastroparesis. Altogether, our results demonstrate that digestion can have a significant impact on fibre viscosity and should be taken into consideration when evaluating the suitability of fibres for patients with gastric motility disorders.

THE SEPARATION OF CALF THYMUS NUCLEIC ACID AND HISTONE BY ALCOHOL–SALT PRECIPITATION

1955 ◽  
Vol 33 (1) ◽  
pp. 263-271 ◽  
Author(s):  
L. B. Smillie ◽  
A. M. Marko ◽  
G. C. Butler
Keyword(s):  
Sodium Chloride ◽  
Nucleic Acid ◽  
Aqueous Solutions ◽  
Distilled Water ◽  
Salt Precipitation ◽  
Salt Solutions ◽  
Desoxyribonucleic Acid ◽  
Concentrated Aqueous Solutions ◽  
Calf Thymus ◽  
Quantitative Separation

Extraction of the histone of thymonucleoprotein with alcohol and salt has been studied with varying concentrations of alcohol, sodium chloride, and nucleoprotein and with varying pH and temperature. The addition of 0.5–1.0 volumes of ethanol to a solution of nucleoprotein (approximately 1 mgm. N/ml.) in 3 M sodium chloride has been found to effect an almost quantitative separation of desoxyribonucleic acid and protein. It has proved feasible to prepare concentrated aqueous solutions of the extracted protein by successive dialysis against strong salt solutions at −10 °C. and against distilled water at 5 °C. followed by pervaporation at 5 °C. The properties of the isolated nucleate have indicated a highly polymerized product.

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