Shear Stress-shear Rate Data Research Articles

Oil-based drilling mud comprising biosurfactant and hydrophobic zinc nano-powders with excellent H2S scavenging performance

Hydrogen sulfide (H2S) could be released during the drilling operations of oil and gas wells. The release of this lethal gas to the surface will expose the working personnel to high safety and health risks. Additionally, the contact of this very corrosive gas with handling and processing equipment will result in severe economic losses. Despite such serious issues, formulating and testing oil-based muds (OBMs) with H2S scavenging capability is still lacking in the literature. Thus, the key aim of this study is to formulate invert emulsion diesel-based drilling mud (abbreviated as IEDBM) that is capable of effectively scavenge H2S in-situ once it is encountered. This aim is realized through the addition of a small quantity of potassium permanganate to the formulated IEDBM. According to the obtained results, the inclusion of a small amount of potassium permanganate (i.e., 1 wt.%) can scavenge up to 0.43 and 0.71 kg H2S per barrel of the formulated mud at the breakthrough (i.e., 29.8 h) and saturation (i.e., 86.2 h) times, respectively. The IEDBM was stabilized using Span 80 (a non-ionic surfactant) and rhamnolipid anionic biosurfactant. The IEDBM also comprised hydrophobic zinc nano-powders (contact angle with water ∼105⁰) as weighting agent. The application of rhamnolipid biosurfactant and hydrophobic zinc nano-powders in drilling formulations is another novel aspect of the work reported herein. The shear rate-shear stress data were well fitted using the Bingham plastic, Casson, and Herschel–Bulkley models. The apparent viscosity of the IEDBM was investigated under different shear rates and the obtained results showed a sharp drop in the mud apparent viscosity with increasing the shear rate up to 40 s−1, followed by a slower decrease upon the further increase in the applied shear rate; which is in line with those of OBMs reported in the literature. The effect of temperature on the apparent viscosity of the IEDBM was also investigated; the change in the mud viscosity was found to be inversely proportional to temperature in almost a linear fashion. The results presented in this work reveal the high potential of formulating OBMs with effective H2S scavenging performance and appropriate flow properties.

Rheological Study of Formate (Nacl) and Ethylene Glycol Based Drilling Fluid Using MATLAB

Non-Newtonian models are used in describing the rheology of drilling fluids. Models, such as Power Law, Bingham Plastic, and the Hershel-Buckley model are used to predict drilling fluid behaviour. Selection of the best rheological model that accurately represents the shear stress-shear rate data is optimal in determining fluid use and predicting realistic rheological behaviour. This research is aimed at studying the best rheology model to fit collected data from sodium chloride (NaCl) and ethylene glycol (EG) based drilling fluid. The assessment utilized a total of ten sets of experimental viscometry data from laboratory-formulated drilling fluid samples A to J with the varying volume of formate sodium chloride (NaCl) and ethylene glycol (EG). Using Equations relating shear rates to shear stress, MATLAB non-linear regression approach was used to determine the best of the three rheological models to fit the experimental. The Root square (R2), Adjusted Root square (Adj R2), and Root Mean Square Error (RMSE) were used in determining the goodness of fit and degree of deviation of the experimental data. data. High concentrations of both NaCl and ethylene glycols in the formulation provide a better shear rate shear stress fit. Although the ethylene glycol presence may have account for the improved fit, as Sample E, F and G despite containing high volume of the formate NaCl, the data where not effectively fitted by the models. From the results, the power law model was the least suitable with an R2 value of 0.881-0.956, Adj R2 83-96%, and a poor RSME in the range 2-9. The Herschel-Bulkley model showed an improved fit for the fluids with an R2 0.897-0.973, Adj R287- 98%, and a better RSME <3. this model also shows a good shear thinning behaviour from its three parameter consistency (n) index values. The Bingham plastic model best fits the rheology of the drilling fluid data R2 0.93-0.99, Adj R2 93-98%, and RSME of <2.

High pressure homogenization of mechanically deboned chicken meat protein suspensions to improve mechanical and barrier properties of edible films

The effect of high pressure homogenization (HPH) on edible films obtained from mechanically deboned chicken meat proteins (MDCM-P), a by-product of poultry industry, was investigated. Film forming suspensions (FFS) were prepared at 4% protein concentration and homogenized up to 150 MPa. FFSs were characterized in terms of particle size and steady shear rheology, whereas optical, barrier, mechanical and microstructural properties of resulting films were determined. Particle size of suspensions decreased as homogenization pressure increased, and suspensions treated up to 50 MPa showed shear thinning behavior with higher yield stress, while higher HPH treatment caused Newtonian flow. Shear stress-shear rate data were fitted to Herschel-Bulkley model. HPH treatment improved film appearance, and all films displayed good barrier properties against UV light which induces lipid oxidations in foods. The decreasing particle size of HPH treated MDCM-P suspensions up to 100 MPa caused lower water vapour permeability (WVP) and higher tensile strength (TS), and these results were also confirmed by film micrographs which had homogeneous, non-porous and un-cracked surface images. However, porous cross sectional images were observed from 150 MPa HPH treated films. FTIR spectra of films showed similar backbone structure, and the secondary structure of films was analyzed from the area of the deconvoluted Amide I peak, which changed significantly. β-sheet and β-turn contents of films showed high correlation coefficients with TS and EAB values. It can be concluded from this study that HPH applications up to 100 MPa can enhance the mechanical and barrier properties of films.

Modelling of Rheological Properties of Mango (cv. Neelum) Suspensions: Effect of Sample Concentration and Particle Size

Evaluation of rheological properties of reconstituted mango peel powder (MPP) cv. Neelum at different particle sizes and sample concentrations was investigated. The combined effect of sample (MPP: water) concentration (1:4, 1:5, 1:6) and particle size obtained from sieve openings (420 µm, 355 µm, 250 µm and 125 µm) were evaluated on the rheological parameters (yield stress, flow behaviour index and consistency index). Lightness (L) and yellowness (b) increased while greenness (a) decreased with reduction in particle size. The increase in sample concentration was associated with increase in shear stress values. Rheological characterization was performed on the basis of coefficient of determination (R2 ) and other model parameters. For the samples (particle size of 250μm and 125μm), the Herschel-Bulkey model (R2 ≥0.831), Power law (R2 ≥0.803) and Casson law (R2 ≥0.832) fitted well to shear stress-shear rate data.

Flow curve analysis of a Pickering emulsion-polymerized PEDOT:PSS/PS-based electrorheological fluid

The steady shear electrorheological (ER) response of poly(3, 4-ethylenedioxythiophene): poly(styrene sulfonate)/polystyrene (PEDOT:PSS/PS) composite particles, which were initially fabricated from Pickering emulsion polymerization, was tested with a 10 vol% ER fluid dispersed in a silicone oil. The model independent shear rate and yield stress obtained from the raw torque-rotational speed data using a Couette type rotational rheometer under an applied electric field strength were then analyzed by Tikhonov regularization, which is the most suitable technique for solving an ill-posed inverse problem. The shear stress-shear rate data also fitted well with the data extracted from the Bingham fluid model.

Influence of particle size on rheological properties of mango peel powder

This study was envisaged to investigate the effect of particle size on the rheological characteristics ofmango cv. Bangalora peel powder under ambient conditions using a rotational rheometer. The consequencesof sample concentration, i.e., powder: water (1: 4, 1: 5, 1: 6) was also evaluated. Sieve analysis using screens(420, 355, 250, 125 microns) was done to achieve the desired variation in particle size. Shear stress-shear ratedata was adequately fitted to Herschel-Bulkey, Power law and Casson law and the rheological properties wererepresented graphically by rheograms for 0 to 100 s−1 shear rate. Relative parameters and regression analysisagainst each model determined the flow characteristics of the samples. Selected three models showed wellrepresentation of the rheological data, with high regression coefficients. Model parameters (consistencycoefficient, flow behaviour index and R2) validated the deviation in rheological characteristics with particle sizeand sample concentration. Shear stress (τ) increases steeply with sample concentration for equivalent particlesize, however, for the same sample concentration, negative correlation of particle size with shear stress wasreported. The identification of suitable particle size and sample concentration might be useful in understandingof rheological properties of the peel powder of selected cultivar.

Comparison of rheological models for jet grout cement mixtures with various stabilizers

The use of jet grouting technique for ground improvement has become very popular approach for civil engineering projects. Despite the availability of large number research related to development of this technique, the rheological models of grout flow have still become in concern for jet grout applications. Thus, an investigation on the performances of the most common rheological models (Bingham, Modified Bingham, Casson, Herschel-Bulkley, Robertson-Stiff, De Kee) for prediction of flow behavior in terms of the shear stresses due to the cement grout mixtures incorporating with the stabilizers of clay, sand, lime, bottom ash in various proportions (0–100%) has been addressed in this article for jet grouting. For this purpose, a thorough comparison of the rheological models has been performed using the flow curves of the shear stress-shear rate data collected from previous study. On the basis of the comparisons, the performances have been presented in a ranking scheme that represents the favorable models within the low to high ranking. It is found from the performances that all rheological models, except the Casson, at most of the stabilizer inclusions have been adequately fitted to the shear stress-shear rate data, resulting in the lower errors (MAE, RMSE) and the strong correlations (R>0.8) with a significant evidence (p<0.05). It is proposed from the ranking scheme that the Robertson-Stiff model and derived formulas in this study are most acceptable (high ranking), the De Kee model is moderate acceptable (moderate ranking), the Herschel-Bulkley and Modified Bingham models are less to moderate acceptable (low to moderate ranking), the Bingham model is least acceptable (low ranking), and the Casson model is unacceptable. Applicability of the ranking performances is relatively promising for jet grouting when compared with the measured shear stress-shear rate data.

Steady shear flow behavior of sage seed gum affected by various salts and sugars: Time-independent properties

The rheological properties of food hydrocolloids are remarkably influenced by the quality of solvent/cosolutes in a food system. In this work, the steady shear flow behavior of sage seed gum (SSG, 0.5% w/w) at the presence of different levels of salts (KCl & MgCl2, 0–100mM) and sugars (sucrose, lactose & glucose, 0–6% w/w) was studied. It was found that the rheological properties of SSG were affected by the type of sugars and salts and their concentrations as well. Synergistic interaction was observed between SSG and sugars which enhanced the viscosity of gum solutions, while salts addition diminished the viscosity. SSG solutions exhibited a shear thinning behavior at all conditions tested. Various time-independent rheological models were used to fit the shear stress-shear rate data, although the Herschel-Bulkley (R2=0.994–0.999) and Sisko (R2=0.995–0.999) models showed the best results to describe the flow behavior of SSG. In the presence of salts, the yield stress (τ0), consistency coefficient (k), and flow behavior index (n) values decreased. The k and τ0 values enhanced and the n value lowered in the presence of sugars. Divalent cations of Mg2+ and sucrose roughly showed more effect on rheological parameters than others.

Scale-Up of Flat Bladed Mixer in Orange Juice Concentrate Process

Mixing of orange concentrates to be homogenized was investigated using flat – bladed impeller. The rheological properties of orange juice concentrate were studied over the range 10-70°C, solid concentration 66 wt% and speed of spindle 50-250 rpm. Shear stress-shear rate data indicate that the concentrate behaves as non-Newtonian pesudoplastic fluid. Geometry was studied by varying the impeller to a column diameter. An impeller mixer was connected to an ammeter in order to predict the power of the mixer. The relation between a power number, blend number, pumping number and Reynolds's number were calculated at different D/T. Scale-up of the mixing process from the laboratory to the production plant scale was carried out utilizing the aforementioned correlations.

Rheological properties of low fat yogurt containing cress seed gum

Yogurt—a milk based mix fermented by lactic acid bacteria is a valuable health food for both young and old. Milk is the main ingredient of yogurt. However, most yogurts contain additional solids such as milk solids nonfat to boost the nonfat milk solids. Stabilizers such as natural gums are added to improve and maintain gel firmness and consistency, while also for many people to improve appearance and mouth feel. Hydrocolloidsspecifically stabilize gel structure, increaseviscosity and either from networks with milk constituents and establish a separate gel structure. In current research, a natural local plant Iranian hydrocolloid, cress seed gum, is added to yogurt formulation and its rheological propertiesare evaluated using a rotational viscometer. Different famous rheological models have beenused to fit shear stress-shear rate data’s. The results demonstrated that cress seed gum has a good potential to be used as a stabilizer in yogurt formula.

Rheological modification of corn stover biomass at high solids concentrations

Additives were tested for their ability to modify the rheology of lignocellulosic biomass. Additive types included water-soluble polymers (WSPs), surfactants, and fine particles. WSPs were the most effective rheological modifiers, reducing yield stresses of concentrated biomass by 60–80% for additive concentrations of 1–2 wt. % (based on mass of dry biomass solids). Yield stress and plastic viscosity of rheologically modified biomass depended on WSP molecular weight and degree of substitution. The apparent shear stress-shear rate data are represented with the Bingham model. In the absence of WSP, the biomass exhibited a positive yield stress and a negative plastic viscosity, which suggests a nonmonotonic dependence of shear stress on shear rate. When WSP was added, the yield stress decreased and the plastic viscosity increased, becoming positive for sufficiently large WSP concentrations.

Rheological and Textural Characteristics of Date Paste

The rheological properties of two commercial date pastes were investigated in the temperature range of 20–70°C. From typical flow behavior curves, it was observed that date pastes exhibited pseudoplastic behavior. The shear stress-shear rate data were fitted using six common rheological models. The Casson model best described the experimental data at all temperatures. The Arrhenius model described successfully the temperature dependence of apparent viscosity of date pastes (R2 > 0.99) with an Ea value in the range of 25,392.6–25,485.7 kJ/kmol. The textural attributes measured were: hardness, springiness, gumminess, cohesiveness, chewiness, and adhesiveness for the texture profile analysis test, and firmness, adhesive force, mean load, and total positive area for the Ottawa test. There was a significant difference in textural attributes between two varieties of date paste studied. Texture profile analysis results showed that all parameters obtained for black date pastes were higher than golden date pastes except for springiness and cohesiveness. However, the Ottawa results showed that golden date pastes were firmer and less adhesive than black date pastes.

Effect of temperature on rheological characteristics of ginger paste

The influences of temperature (25 ? 65 oC) on the rheological characteristics of ginger paste were studied using a rheometer. Shear stress, shear rate and apparent viscosity of paste were measured between 50 and 150 s-1. Ginger paste showed pseudoplasticity with yield stress. Shear stress-shear rate data was well described by the Herschel-Bulkley model. The yield stress decreased exponentially with process temperature and ranged between 63.3 and 159.2 Pa. the flow behavior index (n) varied between 0.52 and 0.66 through the entire temperature range. Both consistency index (K) and apparent viscosity (?) decreased with the increase in temperature and the process activation energies of flow were found to be in the range of 34.4 and 46.2 kJ/mol.

Colour kinetics and rheology of coriander leaf puree and storage characteristics of the paste

Coriander leaves have been used as a food flavourant in various cuisines since ancient times. The colour degradation kinetics of coriander leaf puree was studied using a fraction conversion technique during thermal treatment at 50, 65, 80, 95 and 110 °C for up to 60 min. Blanched, comminuted coriander leaf puree was subjected to heat treatment at selected temperatures in an oil bath with agitation. Treated samples were removed from the bath at selected time intervals (0–60 min after come-up period), cooled immediately and analyzed for colour using a Hunterlab colourimeter. The rheological characteristics of the puree were evaluated using a computer-controlled Haake rotational viscometer at 50, 60, 70 and 80 °C and it was found that the Herschel–Bulkley model adequately represented shear stress-shear rate data. Temperature dependency of the consistency index and apparent viscosity at a shear rate of 100 s −1 followed the Arrhenius relationship and the flow activation energy ranged between 17.2 and 17.9 kJ/mol. Coriander puree was converted to paste by adding common salt (2%) and the required volume of citric acid to adjust the pH to 4.2. The paste was then filled into glass bottles and stored at selected temperatures (5, 25 and 37 °C) for 6 months and was periodically evaluated for colour, total aerobic plate count and physicochemical properties. Coriander puree/paste colour was expressed in terms of tristimulus colour value a and combination ( L× a× b). First order reaction kinetics adequately described the changes in colour values during both thermal treatment of puree and storage of paste. The process activation energies were 29.3 and 22.1 kJ/mol, respectively, for a and ( L× a× b) during thermal treatment. The corresponding values during storage were 12.7 and 12.2 kJ/mol. The paste was microbiologically stable with no significant changes ( P>0.05) in physicochemical characteristics during storage.

Applicability of rheological models to high-performance grouts containing supplementary cementitious materials and viscosity enhancing admixture

The knowledge of yield stress and plastic viscosity of cement-based materials is of special interest in various applications, including consolidation grouting, post-tensioning systems, and for numerical simulations. These rheological parameters are generally estimated from the shear stress-shear rate data using an empirical model. Highly pseudoplastic systems may not be adequately modeled using flow models typically used for conventional grouts. This paper summarizes the results of a study undertaken to evaluate the applicability of a number of analytical models to fit experimental data obtained on cement grout. In total, 44 grouts containing silica fume replacements of 1.5%, 3%, and 5% by mass of cementitious materials, blast furnace slag substitutions of 20% and 40%, and various combinations of high-range water-reducer and viscosity-enhancing admixture were evaluated. All mixtures were prepared with 0.40 water-cementitious material ratio.

Effect of High-Hydrostatic Pressure and Temperature on Rheological Characteristics of Glycomacropeptide

The influences of high pressure and temperature on the rheological characteristics of glycomacropeptide (GMP) were studied using a controlled rate rheometer. GMP dispersions at a concentration of 12.5% (w/w) were subjected to high pressure from 100 to 400MPa for 30min and temperature from 20 to 80°C for 15min followed by rheological measurements at a shear rate ranged between 0 and 200s−1. Shear stress-shear rate data of both pressure and heat induced GMP samples fitted Herschel-Bulkley model well with yield stress. It exhibited shear-thinning behavior with flow behavior index ranged between 0.882 and 0.996. Consistency coefficient and apparent viscosity increased with pressure up to 300MPa while those parameters decreased at 400MPa. The rheology of GMP was influenced by temperature. The consistency coefficient and apparent viscosity at 100s−1 obeyed the Arrhenius relationship with activation energies ranged between 8.17 to 12.38kJ/mol. Lower activation energy signified lesser molecular aggregation or unfolding of protein molecules during thermal treatment of GMP.

End Effect Evaluation in Rheological Measurement of Drilling Fluids Using Coutte Coaxial Cylinder Viscometer

This paper demonstrates the order of influence of end effects on the application of a theory to determine and correct the end effects in Couette coaxial cylinder rotational viscometers, which are commonly used for the rheological evaluation of drilling fluids. It is found that higher shear stresses are measured due to end effects and, consequently, this error bearing shear stress-shear rate data leads to unreliable predictions of the rheological parameters. Evaluation of the shear stress-shear rate data obtained from various drilling fluids indicates that the flow curve corrected for end effects deviates significantly from the measured curve. A parametric analysis for the rheological models, such as the Bingham plastic, power law, and yield-pseudo-plastic models, is also performed with the parameters of the selected rheological model.

Effect of ethylene–vinyl acetate copolymer on the rheological behaviour of alumino-silicate/polyethylene wax suspensions

Ceramic suspensions were prepared from an alumino-silicate powder, polyethylene wax (PE-wax) as binder with additions of stearic acid (SA). The ceramic powder consisted of mullite, corundum and tridymite phases. The organic binders contained 3 to 8 wt.% ethylene–vinyl acetate (EVA) and were filled with various volume fractions of ceramic powder. The yield stresses of suspensions were estimated using shear stress-shear rate data measured at 90–120 °C. The addition level of EVA was shown to have a considerable effect on the yield stress of suspensions. The effect of EVA on the flow parameters was also investigated over the temperature range of 90 to 120 °C. It was shown that the addition of 5 wt.% EVA in organic binder causes a decrease of viscosity at a temperature of 90 °C and the higher the volume fraction of ceramic powder, the higher the efficiency of EVA in reducing the viscosity. But at higher temperature, EVA acts as a flow modifier rather than increasing the wettability of polymer blend. In fact at this temperature the polymer–particle interaction weakens with EVA content. Moreover, it was found that the required amount of EVA depends on the degree of powder agglomeration.

EFFECT OF PROCESSING, PRESERVATION AND STORAGE ON RHEOLOGY OF GUAVA PULP

ABSTRACTRheological behavior of white and pink guava pulps was investigated using Rheotest 2 coaxial cylinder viscometer over shear rates of 0.6 to 145.8 s−1. The shear rate‐shear stress data followed the power law, Casson, Herschel‐Bulkley, Michaels and Bolger models. The power law flow behavior index values were in the range of 0.14 to 0.19. Presence of measurable yield stress indicated Bingham model of the pulps. Storage of pulps for 30 weeks had negligible influence on flow behavior index values. The consistency index and yield stress values decreased with extending storage from 0 to 30 weeks. The Michaels and Bolger model distinctly described the non‐Newtonian nature of cold‐ and hot‐break pulps as well as different behavior of the pink guava pulps. The structure shear resistance values for hot‐break pulps at zero shear rate were considerably higher than those of the cold‐break, indicating their high pseudoplasticity.

PHYSICO-CHEMICAL CHANGES DURING ENZYMATIC LIQUEFACTION of MANGO PULP (cv. Keitt)

Mango pulp from Keitt variety was liquefied with 1.1 mL/kg commercial enzyme mixture preparations for 2 h at 40C. Various physico-chemical characteristics of the mango pulp at different stages of liquefaction were investigated. Apparent viscosity of pulp and serum reduced rapidly to 78% and 93% respectively, in 30 min liquefaction. No marked changes in apparent viscosity of pulp samples and percentage cell wall hydrolysis in the subsequent 60, 90 and 120 min were observed. High correlation coefficient values (R2 > 0.99) of the linear regression analysis showed the feasibility of using a power law model for fitting the shear stress-shear rate data of the pulp. the enzymetreated pulp showed 83% and 84% serum yields during 30 and 120 min reaction times respectively against 52% for fresh pulp. Slight increase in TSS (°Brix), acidity, reducing and total sugars, and slight decrease in pH was found in the pulp as well as serum fractions as the incubation continued. No marked change in color (yellowness) was observed in the enzyme-treated pulp, however, the corresponding serum showed less yellowness and color saturation indicating retention of yellow pigments in the pulp fraction. Δ-3-carene was identified as major mono terpenic compound in mango pulp comprising more than 73% of the total aroma compounds. About 9% loss in the total aroma components was observed during the liquefaction process.