Apparent Viscosity Values Research Articles

Effect of storage on the rheological and viscoelastic properties of mayonnaise emulsions of different oil droplet size

The rheological and viscoelastic properties of mayonnaise emulsions with different size of oil droplets were investigated. Α programmable rotational rheometer was used for the measurements and flow curves were determined at constant and variable shear rate. Mayonnaise exhibited a non-Newtonian, shear-thinning flow with yield stress and time-dependent features. The data from rotational tests were modeled by the Herschel-Bulkley equation. The temperature-dependence of ηa was modelled using the Arrhenius equation. Activation energy, Ea ranged from 15 to 20 kJ/mol. Viscoelastic properties were characterized using small amplitude oscillatory shear. Mayonnaise exhibited weak gel-like properties. The values of apparent and complex viscosity were correlated using the generalised Cox-Merz rule. According to the obtained values of parameter α, this rule could not be cut-down to one-parameter linear function. The rheological characteristics of mayonnaise were well correlated to the size of oil droplets.

Application of Nanosilica in Glycerol-Based Drilling Fluid for Shale Formations

SummaryIn this study, we perform several tests to develop a formula of glycerol-based drilling fluid that is suitable for shale formations with severe wellbore instability problems. Drilling fluids with varying combinations of nanosilica, glycerol, sodium carboxymethyl cellulose (Na-CMC), and xanthan gum (XG) in organic soil glycerol-based slurry are tested, and the effects of nanosilica on the swelling of shale samples and the lubricity of drilling fluids are also investigated to verify the feasibility of designed drilling fluids. The experimental investigations reveal that the values of apparent viscosity (AV), plastic viscosity (PV), and yield value (YP) of the optimal formulation meet the rheological parameters required for the drilling of shale formations. The AV and PV values of drilling fluid with 55:45 glycerol/water ratio are lower than those of drilling fluids with other glycerol/water ratios. A higher XG content means higher YP value in the experiment and 0.4% XG is suitable for the glycerol-based drilling fluid to prevent the collapse of the shale wellbore. There is a critical nanosilica content threshold (0.5%), and the filtration loss (FL) increases gradually when this threshold is exceeded due to the agglomeration of nanosilica. The nanosilica coated on clay particles in shales because of the formation of hydrogen bonds results in a decrease in permeability of shale formations. The swelling of shale through hydration is greatly reduced by 37% and the sticking coefficient of drilling fluid is reduced by 28% when 0.5% nanosilica is added. The addition of nanosilica to glycerol-based drilling fluid is significant to deal with the wellbore instability problems in troublesome shale formations.

Evaluation of physicochemical, microbiological, texture and microstructure characteristics of set-style yoghurt supplemented with quince seed mucilage powder as a novel natural stabiliser

The effects of quince seed mucilage powder (QSMP) on the physicochemical, microbiological, textural and sensory characteristics of yoghurts were evaluated. Incorporation of QSMP at different levels (0.05–0.2%) accelerated Lactobacillus bulgaricus growth. QSMP-yoghurts had lower syneresis; addition of QSMP at 0.15% and 0.2% prevented syneresis completely. Highest apparent viscosity values were obtained with 0.05% QSMP followed by 0.1%; however, 0.15% and 0.2% QSMP addition caused a significant (p < 0.05) decrease in viscosity. Yoghurts with QSMP showed lower firmness, consistency and cohesiveness values compared with the plain yoghurt. Microstructure analysis showed the casein network of the yoghurts with 0.15% and 0.2% QSMP was less compact and cohesive, with a thinner gel structure than that of other yoghurts. QSMP addition at levels of 0.05% and 0.1% was more acceptable to panellists in terms of flavour, odour and mouthfeel and addition higher than these levels caused a decrease in sensory attribute scores.

Effects of different nut oils on the structures and properties of gel‐like emulsions induced by ultrasound using soy protein as an emulsifier

SummaryGel‐like emulsions were produced by high‐intensity ultrasound (HIU) emulsification using soy protein as an emulsifier. Sunflower (a seed kernel oil), peanut (a groundnut oil), hazelnut, walnut, almond and pine nut oils were chosen as oil phases. The kinds of nut oil significantly affect the structures and properties of gel‐like emulsions. The particle size of sunflower oil gel‐like emulsion was smallest. Moreover, the macrorheological and microrheological results indicated that the values of apparent viscosity, storage modulus (G′) and elasticity index (EI) of sunflower and almond oil gel‐like emulsions were higher while those of the walnut and pine nut oil gel‐like emulsions were lower. Moreover, the sunflower oil gel‐like emulsion was more stable after 2‐month storage. The current study illustrated that HIU was of great importance for the production of high‐viscosity gel‐like emulsions. Furthermore, the differences of nut oils resulted in diverse physicochemical properties of gel‐like emulsions.

A semi-empirical model to estimate the apparent viscosity of dense, bubbling gas-solid suspension

A semi-empirical model was proposed to estimate the apparent viscosity of gas-fluidized suspensions. This new model was derived by assuming that a suspension consisted of the bubble phase and the emulsion phase. A set of experimental measurements were also conducted to verify the validity of the proposed model as well as the models in the literature. The results indicated that none of the tested literature models provided satisfactory predictions for the fluidized gas-solid suspension over the mentioned target particle volume fraction range. The estimation using the newly proposed model generally well agreed with the experimental apparent viscosity values of the gas-solid suspensions composed of gas-fluidized Geldart Group A or B particles, as most of the estimated values situated within the ±25% error bars. The proposed model is of special significance as it provides a quick estimation method of the apparent viscosity of a gas-solid suspension flow in the engineering calculation.

Measurement of human blood viscosity a using Falling Needle Rheometer and the correlation to the Modified Herschel-Bulkley model equation

We measured the blood viscosity of 25 male and 25 female healthy people (total 50) using a compact-sized falling needle viscometer (Falling Needle Rheometer) capable of highly accurate measurements. Based on the analysis of the flow characteristics, most of the blood specific non-Newtonian fluid (Casson fluid) behavior was confirmed. Additionally, the blood from males has a higher apparent viscosity and Casson yield value than that from women. Furthermore, a new Herschel-Bulkley type model equation representing the relationship between the shear rate and apparent viscosity of human blood was proposed based on the measured blood flow characteristics. The proposed model improved the exponential term on the shear rate and added the constant term on the yield stress so that the measured value can be correlated with a high accuracy. Using the proposed model equation, the correlation accuracy of all of the measured human blood viscosities was better than in the Herschel-Bulkley model equation and Casson model in a wide range of shear rate regions. By incorporating numerical flow analysis (computational fluid dynamics), this model equation may contribute to analyses considering the non-Newtonian fluidity of human blood.

Interfacial rheology for the assessment of potential health effects of inhaled carbon nanomaterials at variable breathing conditions

Lung surface is the first line of contact between inhaled carbon nanomaterials, CNMs, and the organism, so this is the place where pulmonary health effects begin. The paper analyzes the influence of several CNMs (single- and multi-walled nanotubes with various surface area: 90–1,280 m2/g and aspect ratio: 8–3,750) on the surface-active properties of the lung surfactant, LS, model (Survanta). Effects of CNM concentration (0.1–1 mg/ml) and surface oscillation rate were determined using the oscillating drop method at simulated breathing conditions (2–10 s per cycle, 37 °C). Based on the values of apparent elasticity and viscosity of the interfacial region, new parameters: Sε and Sμ were proposed to evaluate potential effect of particles on the LS at various breathing rates. Some of tested CNMs (e.g., COOH- functionalized short nanotubes) significantly influenced the surfactant dynamics, while the other had weaker effects even at high particle concentration. Analysis of changes in Sε and Sμ provides a new way to evaluate of a possible disturbance of the basic functions of LS. The results show that the expected pulmonary effects caused by inhaled CNMs at variable breathing rate depend not only on particle concentration (inhaled dose) but also on their size, structure and surface properties.

Investigation of Rheological Behavior of Untreated and Microwave-Assisted Alkaline Pretreated Sugarcane Straw for Biofuel Production

Biomass slurries, such as those subjected to microwave-assisted alkaline (MAA) pretreatment, will become common substrates for the production of biofuels in the future. While the rheology of acid and ionic liquid pretreated biomass is known, the rheology of alkaline pretreated biomass is not yet reported; hence, the goal of this study was to establish the rheological characteristics of untreated and MAA pretreated sugarcane straw (SC). Using rotational rheometry and rheological models, the rheology of SC slurries was assessed as a function of particle size and insoluble solids concentration. In the range of 5–17% insoluble solids concentration, the slurries were consistently pseudo-plastic (n = 0.33 ± 0.02), possessed yield stress with their flow accurately described by the Casson rheological model (R2 = 0.98–0.99). The apparent viscosity and yield stress increased by two orders of magnitude with an increase in insoluble solids concentration. Essentially, MAA pretreated slurries exhibited significantly higher values of apparent viscosity and yield stress than the untreated ones, in the range of 55–80% and 21–63% for particle sizes of < 63 µm (P63) and 90–180 µm (P90), respectively. Pretreated P63 samples exhibited higher apparent viscosity and yield stress than the P90. On the other hand, for untreated samples, P63 samples had a reduced apparent viscosity than P90 samples. The results of this study definitively reveal that MAA significantly increases the shear rate dependent shear viscosity values along with the yield stress of biomass slurries. This will, therefore, serve as a benchmark for characterizing other MAA pretreated biomass slurries to guide the design of industrial-scale production equipment.

Milk protein concentrates 80: Does composition of buffalo milk matter for its poor functionality?

Poor solubility is the major problem in high-protein milk protein concentrates (MPC). Therefore, present investigation aimed at producing and characterizing buffalo milk-based milk protein concentrate 80 (BM-MPC80) for its physicochemical, functional and reconstitution properties; morphological characteristics and rheological behaviour. The UF concentrate (0.80 protein to total solids ratio) obtained through ultrafiltration (UF) of pasteurized buffalo skim milk was spray-dried at 200/95 ± 5 °C to obtain BM-MPC80 powder. It was observed that solubility (24.40 ± 0.84%), heat stability (1.00 ± 0.00 min), porosity (34.90 ± 1.20%), dispersibility (7.43 ± 0.26%), specific surface area (36.60 ± 1.59 m2/kg) and flowability (43.56 ± 1.69°) values of BM-MPC80 powder were lower than counterpart. Its particle density, dispersion index, wettability, water activity, apparent viscosity (at 20 °C, 50 s−1), foam capacity and stability values were 0.56 ± 0.02 g/mL, 1.20 ± 0.89%, 6.33 ± 0.32s, 0.12 ± 0.00, 0.455 ± 0.00Pas, 36.27 ± 1.56%, and 70.53 ± 1.34%, respectively. Scanning electron micrographs revealed extensive aggregation in BM-MPC80 powder particles, which could be responsible for its poor solubility and dispersibility. Shear-thinning behaviour was observed in UF concentrate and reconstituted BM-MPC80 solution. Overall, this study established that composition of buffalo milk is responsible for poor functional and reconstitution properties of BM-MPC80 powder.

Whey Protein Concentrate and Egg White Powder as Structuring Agents of Double Emulsions for Food Applications

This work aims at studying the effects of whey protein concentrate (WP) and egg white powder (EW) as structuring agents in double emulsions (W1/O/W2). A D-optimal design was developed considering the following factors: type (WP, EW) and concentration (0, 5, 10 g/100 mL) of protein used to gel the inner water phase (W1), W1 volume percentage (20%, 30%, and 40%) in primary emulsion (W1/O), and W1/O volume percentage (40, 50, 60%) in W1/O/W2. The 21 samples were investigated by FT-IR spectroscopy, which revealed different protein conformations depending on W1 and W1/O fractions, and a better interaction with oil of WP rather than EW. Highly significant (p < 0.001) multivariate models were computed for yield, rheological properties, and creaming stability of W1/O/W2, being W1 and W1/O the most influent factors. Protein type significantly affected W1/O/W2 rheology, revealing a better structuring ability of EW with respect to WP, resulting in higher apparent viscosity and consistency coefficient values. A W1/O/W2 optimized for maximum values of apparent viscosity, yield, and creaming stability was developed, composed of 10 g/100 mL EW in W1, 29% W1, and 60% W1/O, with an oil content of 42.6 mL/100 mL. The optimized emulsion gave results in good agreement with the predicted values, thus confirming the validity of the developed multivariate models for the design of double emulsions with desired features.

Effect of particle size on the stability and flavor of cloudy apple juice

Different particle sizes in cloudy apple juice were obtained following filtration with different mesh sizes (100, 200, 300, and 400-mesh). The effects of cloud particle size on the stability, nutrient content, and volatile flavor of cloudy apple juice were evaluated. With increasing mesh number, particle size decreased (p < 0.05) and particle shape changed. Particle size had an effect on volatile flavor compounds, especially nitrogen oxides, alcohols, and aromatic compounds. The content of pectin and total phenol decreased with decreasing particle size, while the content of soluble protein was not affected. The reduction of cloud particle size increased absolute value of ζ-potential, cloud stability, and apparent viscosity and decreased turbidity and cloud values. Pearson correlation analysis showed that there was a strong correlation between particle size and quality indicators, except for soluble protein.

Tunable rheological-tribological performance of “green” gel-like dispersions based on sepiolite and castor oil for lubricant applications

This work has been focused on the preparation and characterization of gel-like dispersions based on sepiolite and castor oil potentially suitable as eco-friendly lubricating greases. Particularity, the effect of sepiolite content exerted on rheological, chemical, thermal and tribological properties was studied. The system exhibited a gel-like behaviour for all the concentrations considered (20–40 wt%) related to the development of a sepiolite three-dimensional colloidal network due to its characteristic nanoscale structure formed by fibers, laths and bundles. The values of both apparent viscosity and viscoelastic functions in the linear viscoelastic region increased with sepiolite content, as a consequence of a strengthening of the gel network. An empirical correlation between viscoelastic modulus and sepiolite concentration was proposed. From tribological point of view, the friction coefficient values and wear marks obtained after the frictional tests became lower when sepiolite concentrations decrease. Gel-like dispersion formulated with 30 wt% sepiolite showed appropriate rheological and tribological behaviour to be used as biolubricating greases.

Printability of a Cellulose Derivative for Extrusion-Based 3D Printing: The Application on a Biodegradable Support Material

Support material plays a leading role in the application of 3D printing to avoid deformation and enhance stability. This study aimed to fabricate the support structure by using hydroxypropyl methylcellulose (HPMC), which has advantages over conventional material such as low cost, low printable temperature, and high biodegradability. Once dissolved in water over gelling temperature, the HPMC based hydrogel exhibited shear-thinning behavior with decreasing apparent viscosity values at higher shear rates. The shear-dependent viscosity makes the HPMC hydrogel extrudable throughout the printing process and the printed structure stable enough without deformation. As concentration increased, apparent viscosity and storage modulus both subsequently increased. These rheological properties indicated that the concentration of HPMC K4M hydrogel significantly influenced the printability and shape retention ability, which is associated with the mechanical strength of printed filaments. The highest concentration, 12% w/v, should have the best ability to hold the printed shape over time due to the highest G' and lowest loss tangent. The printability test also showed that K4M 12% w/v could be printed into different fill density (100%, 75%, and 50%) with different patterns, i.e., rectilinear and Hilbert curve. The selection of fill density and pattern both have an effect on surface roughness and porosity. The printed support material was compatible with acrylonitrile butadiene styrene (ABS), which is the material to fabricate the main structure for 3D printing. The support material made of HPMC can be easily removed by peeling off from the main structure without visible residual.

Influence of MgO and CaCl2 on the rheological properties of bentonitic clays from the new Paraíba-Brazil deposits using experimental planning and statistical analysis

Abstract New deposits of bentonite clays have been discovered in the Brazilian State of Paraíba; the most recent was at the municipality of Olivedos. Recent studies have discovered the presence of high levels of non-clay minerals that can produce unsatisfactory results when attempting to use these clays in drilling fluids. In order to make them suitable for this purpose, the MgO and CaCl2 as chemical additives were used and their influences on the rheological properties of these clays were analyzed, using an experimental planning technique and statistical analysis. The samples were obtained using experimental modeling by the delineation of mixtures technique; first, the clays were transformed with sodium carbonate and then dosed with MgO and CaCl2. The rheological properties, apparent viscosity (AV) and plastic viscosity (PV) were determined according to the Petrobras standard (AV≥15 cP; PV≥4 cP). The results showed that the values of AV and PV increased considerably and that MgO was the additive that contributed most to the improvement of these properties, making these additives suitable for use in water-based drilling fluids.

Influence of processing conditions on rheological properties of aqueous extract chia (Salvia hispanica L.) mucilage

The purpose of this study was to determine the effects of soaking temperature (25 and 80° C) and different processing conditions on the rheological properties of chia seeds (Salvia hispanica L.) mucilage. In this study, chia mucilage was first extracted using a ratio of seed to water at 1:10 for 4 hrs for control (25°C) and treated mucilage (80°C). Both extracted mucilage were evaluated in terms of yield, color, solubility, and water holding capacity. Then, the mucilage were subjected to different processing conditions including temperatures (5, 25, 45, and 65°C), pH (3, 5, 7, 9), sucrose concentrations (10, 20, 30, 40%), and salts (NaCl and KCl from 0 to 0.172 M; CaCl2 and MgCl2 from 0 to 0.049 M) to determine their rheological properties. Results show that high extraction temperature (80°C) significantly affected the mucilage yield higher than control. However, lightness (L*), solubility and water holding capacity of the treated sample were lower compared to control. Apparent viscosity of the 3% of mucilage for both extracts increases with temperatures and sucrose concentration. The high apparent viscosity of the treated mucilage at MgCl2 (0.049 M) and CaCl2 (0.049 M) concentration were found higher than 0.01 M. Meanwhile, NaCl (&gt;0.069 M), KCl (&gt;0.035 M), and CaCl2 (&lt;0.03 M) had decreased the apparent viscosity value of the control sample. Thus, the treated mucilage could be suitable for application as a thickening agent in food.

In vitro angiotensin converting enzyme (ACE)-inhibitory and antioxidant activity of probiotic yogurt incorporated with orange fibre during storage.

In the present work, the effects of orange fibre (OF) supplementation at four different concentrations (0.5%, 1%, 1.5% and 2%) on some quality properties of probiotic set yogurt produced with ABT-2 culture (containing Streptococcus thermophilus ST-20Y, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) were evaluated, during 21days of storage. The in vitro angiotensin converting enzyme (ACE)-inhibitory activity and antoxidant capacity as well as some physicochemical and microbiological analyses of probiotic yogurts were analysed and compared with plain yogurt. At the beginning of storage, yogurt samples had high survivability for probiotic bacteria leading to viable counts (> 107CFU/g) higher than the minimum therapeutic threshold (106CFU/g). A significant influence (p < 0.05) of OF supplementation on S. thermophilus ST-20Y and B. lactis BB-12 counts was observed. While OF addition enhanced the viability of B. lactis BB-12, it caused a decrease in S. thermophilus ST-20Y counts. OF addition up to 1.5% concentration affected positively the syneresis, apparent viscosity and consistency index values of yogurt samples. ACE-inhibitory activity showed an increasing trend throughout the storage. Control yogurt had the lowest ACE-inhibitory activity at 1day of storage, and the highest activity was obtained in yogurt containing 1% OF at the end of the storage. Also, yogurts with OF had higher antioxidant activity than the control sample at all days of storage (p < 0.05). Antioxidant activity increased until 14days of storage in all yogurt batches, while it was decreased 21th days of storage. Briefly, this study reflected the performance of using OF as an alternative hydrocolloid to improve the quality properties and bioactivity of bio-yogurt.

Apparent molar volumes and relative viscosity of [C3C1PYR][Br]/[C2OHC1PYR][Br] + H2O

The binary mixtures of 1-propyl-1-methylpyrrolidinium bromide ([C3C1PYR][Br]) salt and 1-hydroxyethyl-1-methylpyrrolidinium bromide ([C2OHC1PYR][Br]) salt with secondary distilled water were prepared at low concentrations. The density and viscosity of the studied binary mixtures have been determined. The values of the studied properties were recorded every 5 K at temperature range 288.15–318.15 K. The values of apparent molar volume (Vϕ, m3 mol−1) and relative viscosity (ηr) were calculated according to the experimental values of density and viscosity of the systems. The side chains effects in each salt cation are discussed on the above properties. The limiting parameters (Vϕ0, m3 mol−1) were obtained and analyzed by fitting the apparent molar volumes with concentration by a Redlich–Rosenfeld–Meyer equation. The relative viscosities (ηr) were also calculated and analyzed according to the traditional equation of Jones–Dole at different concentration ranges.

Synthesis and Characterization of SiO2NPs/MWCNTs Nanocomposite and Effect on the Properties of Na-Bentonite Water Based Drilling Fluids: Experimental Investigation

Drilling fluid is an essential element of the drilling operations and has many functions. Some of these are wellbore cleaning, checking high formation pressures and corrosion protection, etc. This study aimed to determine the effects of multi-walled carbon nanotubes containing silisyum dioxide nanoparticles (SiO2NPsMWCNTs) were investigated on the rheological and filtration loss properties of Na-Bentonite water based drilling fluids (Na-WBDF).In this context SiO2NPs/MWCNTs was produced by chemical vapor deposition (CVD) method, characterized by X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM), and then added to Na-WBDF in different ratios (0.001 to 0.01% w/v). The rheological properties of the prepared drilling fluids such as plastic viscosity (PV), apparent viscosity (AV), yield point (YP), gel strength (10 s and 10 min) were performed by FANN viscometer, filtration loss and cake thickness were performed by American Petroleum Institute (API) liquid loss test equipment. Compared with spud drilling fluid; SiO2NPs/MWCNTs increased the PV value of Na-WBDF by 71.4%, AV value by 51.9%, YP value by 44%, 10 s and 10 min by 25% and 33.3% respectively, and decreased filtration loss value by 13.8%; At the same time, the value of cake thickness increased by 11%.

Soğuk Press Kiraz (Prunus avium) Çekirdeği Yayının Fizikokimyasal Özellikleri, Yağ Asidi, Sterol, Tokoferol ve Fenolik Bileşen Karakterizasyonu

This study aimed to determine physicochemical properties (PV, FFA, total phenolic content, antioxidant activity), fatty acid, sterol, tocopherol and phenolic compound profile of sweet cherry seed oil. Sweet cherry oil was obtained by cold press process. Tocopherol and phenolic compounds were determined by HPLC and fatty acid and sterol composition were analyzed by GC system. PV and FFA values were found as 1.40 meqO2/kg and 2.71 % respectively. Apparent viscosity value was 0.057 Pa.s. TPC and AC values of the sweet cherry oil were determined as 22.17 mg/kg and 1.05 TE μM g-1. UFA content was higher than that of the SFA. SFA and UFA levels were 10.47% and 89.53 % respectively. MUFA (40.50 %) level was lower than PUFA level (52.03%). Oleic acid and linoleic acid were found to be major fatty acids with a ratio of 36.73% and 39.45 %, respectively. 14 different sterols were analyzed for sweet cherry seed oil. -sitosterol was found to be the major sterol with a ratio of 88.93 % followed by campesterol (3.12%), 7-stigmasterol (2.48%), 5-avenasterol (2.12%) and sitostanol (1.42%). Other sterols showed small amount (<1%). Total four tocopherols namely, , ,  and  tocopherols were identified for sweet cherry oils. -tocopherols (96.72 mg /kg) were found as major tocopherol followed by -tocopherols (57.40 mg/kg) and  tocopherols. -tocopherol showed a small amount. This study suggested that sweet cherry seed oil can be utilized in food industry due to high level of bioactive compounds and low levels of PV and FFA content.

Rheological Characteristics of Waxy Rice Starch Modified by Carboxymethyl Cellulose.

The effects of carboxymethyl cellulose (CMC) at different concentrations (0, 0.2, 0.4, and 0.6% w/w) on the rheological properties of waxy rice starch (WRS) pastes were evaluated under both steady and dynamic shear conditions. The flow properties of WRS-CMC mixtures were determined from the rheological parameters of power law and Casson models. All samples demonstrated a clear trend of shear-thinning behavior (n=0.33~0.34), with a marginal difference shown between n values. The addition of CMC to WRS increased the apparent viscosity (ηa,100), consistency index, and Casson yield stress values. The dynamic moduli [storage modulus (G′), loss modulus (G″), and dynamic viscosity (η*)] and ratio of G″/G′ values of WRS-CMC mixtures also increased with an increase in CMC concentration; the higher dynamic rheological properties observed at higher CMC concentrations may be attributed to an increase in the viscoelasticity of the continuous phase in the starch-gum mixture system. Dependence of ηa,100 on temperature followed the Arrhenius model for all samples. The Cox-Merz rule was not applicable to WRS-CMC pastes with different CMC concentrations, demonstrating that there was a deviation between η* and steady shear viscosities for all samples. Therefore, the synergistic effect of CMC on the rheological properties of WRS pastes appeared to be the result of coacervation.