Aqueous Solution Of Carboxymethyl Cellulose Research Articles

Silver/polysaccharide-based nanofibrous materials synthesized from green chemistry approach

In this contribution a novel green chemistry approach for the synthesis of nanofibrous materials based on blends of carboxymethyl-cellulose (CMC)–silver nanoparticles (AgNPs) composite and polyvinyl-alcohol (PVA) is proposed. These nanofibrous materials were obtained from the electrospinning of blends of aqueous solutions of CMC–AgNPs composite and PVA, which were prepared at different CMC/PVA weight ratios in order to electrospin nanofibers applying a constant tension of 15kV. The synthesized materials were characterized by means of transmission electron microscopy, scanning electron microscopy; as well as Fourier-transform infrared, ultraviolet and Raman spectroscopic techniques. Experimental evidence suggests that the diameter of the nanofibers is thinner than any other reported in the literature regarding the electrospinning of CMC. This feature is related to the interactions of AgNPs with carboxyl functional groups of the CMC, which diminish those between the later and acetyl groups of PVA.

Rheological Property and Thermal Conductivity of Multi-walled Carbon Nano-tubes-dispersed Non-Newtonian Nano-fluids Based on an Aqueous Solution of Carboxymethyl Cellulose

The non-Newtonian nano-fluids with 0.1, 0.5, 1, and 2 wt% of multi-walled carbon nano-tubes have been prepared by dispersing different amounts of multi-walled carbon nano-tubes into an aqueous solution of carboxymethyl cellulose at a weight fraction of 3 wt%, respectively. The nano-fluids exhibit the shear-thinning rheological behavior. The viscosity of the nano-fluid increases with the weight fraction of multi-walled carbon nano-tubes and decreases with the increase in temperature. The thermal conductivity of all the nano-fluids is higher than that of the base liquid. The thermal conductivity enhancement is as high as 14.6% for the nano-fluid containing 2 wt% of multi-walled carbon nano-tubes.

Structure of Sodium Carboxymethyl Cellulose Aqueous Solutions: A SANS and Rheology Study.

We report a small angle neutron scattering (SANS) and rheology study of cellulose derivative polyelectrolyte sodium carboxymethyl cellulose with a degree of substitution of 1.2. Using SANS, we establish that this polymer is molecularly dissolved in water with a locally stiff conformation with a stretching parameter. We determine the cross sectional radius of the chain ( 3.4 Å) and the scaling of the correlation length with concentration (ξ = 296 c−1/2Å for c in g/L) is found to remain unchanged from the semidilute to concentrated crossover as identified by rheology. Viscosity measurements are found to be in qualitative agreement with scaling theory predictions for flexible polyelectrolytes exhibiting semidilute unentangled and entangled regimes, followed by what appears to be a crossover to neutral polymer concentration dependence of viscosity at high concentrations. Yet those higher concentrations, in the concentrated regime defined by rheology, still exhibit a peak in the scattering function that indicates a correlation length that continues to scale as. © 2014 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 492–501

Laminar and Turbulent Flow of Non-Newtonian Fluids in Open Channels for Different Cross-Sectional Shapes

New models for the prediction of laminar and turbulent flow of non-Newtonian fluids in open channels of different cross-sectional shapes are proposed. These models are compared with three previously published models for laminar flow and five previously published models for turbulent flow using a recently extended experimental database for non-Newtonian flow in open channels of different cross-sectional shapes. Flow of three different fluids (aqueous carboxymethylcellulose solutions and kaolin and bentonite suspensions) was investigated in open channels of four different cross sections (rectangular, semicircular, trapezoidal, and triangular) at slopes varying from 1 to 5°. The new laminar model gave a closer fit to the data than those from the previously published models. However, the presence of the yield stress still presents a problem that makes flow prediction in laminar flow for such fluids not very accurate. The new model for turbulent flow gave the best fit to the flow data compared with the five previously published models, which fell within a 30% error margin. A particular advantage of both new models is that they are applicable for all the different fluids tested and the four open channel cross-sectional shapes.

English

Laser Doppler anemometry (LDA) has been employed to quantify the liquid velocity field around a single bubble in its generating and accelerating stage in carboxymethylcellulose (CMC) aqueous solution. The instantanoues velocities were treated by Reynolds time-averaged method, and mean velocities and its contours in both axial and radial directions were investigated. The results show that in vertical direction, the flow field characteristics of the liquids around the bubble are determined by bubble formation-rise mechanism, whereas in horizontal direction they are governed by the relative position with the bubble shear radius. The contours of axial and radial mean velocity in the test section take on the shapes of inverted trapezoid and butterfly forewing, respectively.

Flow Rate Measurement of Non-Newtonian Fluids through Sharp Crested Notches

Sharp crested notches, particularly rectangular and V-shaped ones, have been used to measure the flow rate of water in open channels for a long time. However, they have not been used to measure the flow rate of non-Newtonian fluids. The aim of this work is to explore the possibility of extending their range of application to non-Newtonian fluids, especially for rectangular and V-shaped notches. An experimental facility in the flow process research laboratory was used to perform the extensive tests reported herein. The notches and an in-line tube viscometer were calibrated using water. The in-line tube viscometer was used to determine the fluid rheology. Three different types of non-Newtonian fluids [namely, aqueous solution of carboxymethyl cellulose (CMC) solutions and water-based suspensions of kaolin and bentonite] were used as model test fluids. The experimental values of the coefficient of discharge (Cd) were plotted against three different definitions of the Reynolds number denoting different underlying physical ideas. In the laminar conditions, the discharge coefficient exhibited the classical dependence on the Reynolds number with slopes of approximately 0.43–0.44. On the other hand, the discharge coefficient was nearly constant in the turbulent flow regime. Single composite power-law function was used to correlate the present Cd−R for each of the two notch shapes used here. Using these correlations, the Cd values could be predicted to within ±5% for the rectangular and the V notches.

Исследование реологических и вытесняющих свойств водных растворов натриевой соли карбоксиметилцеллюлозы, как этап в реализации метода полимерного заводнения на месторождениях нефти Непско-Ботуобинской области

Исследование реологических и вытесняющих свойств водных растворов натриевой соли карбоксиметилцеллюлозы, как этап в реализации метода полимерного заводнения на месторождениях нефти Непско-Ботуобинской области

An investigation on the hydrodynamic and heat transfer of nanofluid flow, with non-Newtonian base fluid, in micromixers

Abstract In this study heat transfer and fluid flow of a non-Newtonian nanofluid in two dimensional parallel plate microchannel without and with micromixers have been investigated for nanoparticle volume fractions of ϕ = 0 , ϕ = 0.04 and nanofluid Reynolds numbers of Renf = 5, 20, 50. The nanofluid is composed of CuO nanoparticles and the non-Newtonian base fluid of 0.5 wt% aqueous solution of Carboxymethyl Cellulose (CMC). Two baffles on the bottom and top walls work as micromixer. A single-phase finite difference FORTRAN code using Projection method has been written to solve the governing equations with constant wall temperature boundary condition. A new correlation for thermal conductivity of this nanofluid has been introduced and also the effect of various parameters such as the baffles distance, height and order of arranging has been studied. Results show that the presence of baffles and also increasing the Re number and nanoparticle volume fraction increases the local and average heat transfer and friction coefficients of non-Newtonian nanofluid. Also, the effect of nanoparticle volume fraction on heat transfer coefficient is more than friction coefficient in most of the cases. It was found that the main mechanism of enhancing heat transfer or mixing is the recirculation zones that are created behind the baffles. The size of these zones increases with Re number and baffle height. The fluid pushing toward the wall by the opposed wall baffle and reattaching of separated flow are the locations of local maximum heat transfer and friction coefficients.

Synthesis of Sodium Carboxymethyl Cellulose Based on Pretreated Bamboo Shaving

Bamboo shaving is a by-product of bamboo industry, often be discarded or incinerated. In this work, sodium carboxymethyl cellulose (CMC) was prepared from pretreated bamboo shaving as raw material, while the main reaction conditions affecting product properties such as pretreated method, alkalization temperature and time, etherified temperature and time were studied. The results showed that the optimized pretreated conditions for bamboo cellulose were soaked in 15% NaOH at 1:8 (w/v) ratio of cellulose to solvent for 1 h at 95°C, The content of α-cellulose reach to 94.25%. The optimized reaction conditions for CMC synthesis were alkalified at 30°C for 70 min and etherified at 55°C for 90min; afterwards, temperature was kept at 70°C for 10min. Under these conditions, viscosity of 1% CMC aqueous solution was above 260 mPa·s, degree of substitution (DS)≥0.8, and content of chloride and moisture were less than 1.2 % and 10 % respectively.

Laminar heat transfer performance of power law fluids in coiled square tube with various configurations

This study addresses heat transfer performance of laminar non-Newtonian fluid flow in various configurations of coiled square tubes e.g., in-plane spiral ducts, helical spiral ducts and conical spiral ducts. The non-Newtonian fluid considered in this study is the aqueous solution of carboxymethyl cellulose (CMC) which is modeled as power-law fluid. Effects of tube geometries, power-law index (concentration of CMC) and other parameters are quantified and discussed to analyze flow behavior and heat transfer performance. Results are compared with those for a straight square tube of the same length as that used to form the coils. A Figure of Merit is defined to compare the heat transfer performance of different geometries with respect to the pumping power. The results suggest that CMC solution yields better heat transfer performance of about twice than that of water at Re~1000. Among all considered designs, helical coil gives the best heat transfer performance; however, when the pumping power is considered, in-plane coil design performs the best in term of Figure of Merit.

Experimental study of pseudoplastic fluid flows in a square duct of strong curvature

In this paper, laminar and turbulent flows of pseudoplastic fluids (0.1% and 0.2% by weight aqueous solutions of carboxymethylcellulose) in a square duct of strong curvature were measured using an ultrasonic Doppler velocimetry and microphones. Streamwise velocity in cross-sections of the duct and the fluctuating pressure on walls were measured for different flow rates. The velocity contours and their development along the duct were presented and compared with benchmark experiments by Taylor, Whitelaw and Yianneskis (1982) which were for the laminar and turbulent flows of water. The spectra of fluctuating wall pressures were also presented and analyzed. The objective of this paper was to provide a basis for understanding the pseudoplastic fluid flows in curved ducts. The results were also intended for use in the further development of numerical methods and turbulence models for shear-thinning fluids.

Hydroxyl radical-induced crosslinking and radiation-initiated hydrogel formation in dilute aqueous solutions of carboxymethylcellulose

Ionizing radiation causes chain scission of polysaccharides in the absence of crosslinking agents. It has been demonstrated before that degradation of carboxyalkylated polysaccharides may be prevented, despite presence of strong electrostatic repulsing forces between chains, at very high polymer concentration in water (paste-like state) when physical proximity promotes recombination of radiation-generated polymer radicals. In such conditions, crosslinking dominates over chain scission and covalent, macroscopic gels can be formed. In an approach proposed in this work, neutralizing the charges on carboxymethylcellulose (CMC) by lowering the pH results in retracting the electrostatic repulsion between chain segments and thus allows for substantial reduction of polymer concentration required to achieve gelation due to domination of crosslinking reactions. Electron-beam irradiation of aqueous solutions of low pH containing 0.5–2% CMC results in hydrogel formation with 70% yield, while both concentration and dose determine their swelling properties. Time-resolved studies by laser flash photolysis clearly indicate strong pH influence on decay kinetics of CMC radicals.

Stable Charge/Discharge Cycle Performance of LiFePO4 Cathode Prepared with Carboxymethly Cellulose Binder

Carboxymethyl cellulose (CMC) has recently attracted attention as a binder in lithium ion batteries (LIBs) due to its hydrophilic nature, which has led to its promising electrochemical performance in Si anodes. A water-soluble CMC-based binder has attracted significant interest as it is expected to reduce the cost of LIBs by replacing the conventional organic solvent-based binders. In recent years, the application of CMC has also been demonstrated in a cathode binder. Several groups have attempted to extend the practical applications of the CMC cellulose derivative to the cathode binder. However, the surfaces of an Al foil cathode current collector easily repel the water slurries containing the active cathode materials that include a conductive additive and the CMC binder. Thus, homogeneous, adhesive cathode films cannot form on Al current collector surfaces. Therefore, unlike conventional cathode binders, no stable cell performance could be observed. We altered the Al foil surfaces via chemical treatment, turning a water-slurry-passive surface into an adhesive surface, and used the chemically treated surfaces as the cathode current collector to investigate the effects of the treatment on the cell performance of CMC-based cathodes. The charge/discharge cycle performance of the cathode was compared with that of chemically and mechanically treated Al foils. The Al foils used as current collectors are 99.99% pure with a 100-μm thickness. The chemical treatment of Al foils was referred to in Japanese patents acquired by the Japan Surface Treatment Institute Co., Ltd. 1,2 All slurries were prepared using Milli-Pore water (> 18 MΩ). The CMC1 (degree of etherification = 0.7, viscosity = 1000–2000 mPa·s at 1% AQ, 25 °C) binder purchased from Polyscience Inc., the CMC2 (CMC-2200, degree of etherification = 0.8–1.0, viscosity = 1500–2500 mPa·s at 1% AQ, 25 °C) binder received from Daicel, Japan and the polyvinylidene difluoride (PVdF, KF9130, Kureha, Japan) were used as received without any further treatment to prepare the LiFePO4 cathode. To avoid agglomeration of the cathode material and binder in the cathode film, the mixture containing the LiFePO4 active material and acetylene black was first dispersed in water; then, a CMC aqueous solution was added to this suspension, and the mixture was subsequently magnetically agitated for at least 4 h prior to producing the electrode film. The cathodes were prepared via doctor-blade (100-μm gap) coating. Electrochemical tests were performed using a CR2032 coin-type cell. The test cell was comprised of a cathode and a lithium metal anode separated by a porous polypropylene film (Celgard 3401). The electrolyte used in the tests contained a mixture of 1 M LiPF6-ethylene carbonate (EC)/dimethylcarbonate (DMC) (1:2 v/v, Ube Chemicals, Japan). All tests were performed at room temperature. A constant-current (CC) mode was applied to the pre-treatment process and cycle tests. The cathodes prepared with the chemically treated Al foils exhibited a stable charge/discharge capacity for 100 cycles compared with the mechanically treated Al foils that exhibited poor stability in their charge/discharge capacity (Fig. １). Two of the CMC samples ((a) and (b)) did not exhibit a large difference in their cycle performance, indicating that the degree of etherification and viscosity of the CMC affects the cycle performance. The charge capacities observed during first several cycles were below the stable charge/discharge capacities after several cycles. The decrease in the initial charge capacity can be explained by the deintercalation of the Li+ ions from the LiFePO4particles during their exposure to the aqueous solutions used to prepare the slurry containing the CMC binder. The rate performance is important in the application of LiFePO4 cathodes. All cells were charged at a current of 0.1 C to insure identical initial conditions for each discharge. The discharge currents were 0.1, 0.2, 0.4, 0.8, 1.6 and 3.2 C, indicating that the LiFePO4cathodes prepared with CMC1 and CMC2 exhibit discharge capacities comparable to those obtained using a conventional PVdF binder even at high rate current. Therefore, the CMC binders do not exhibit and negative influence on the rate performance.

A laser imaging-LDV coupling measurement of single bubble forming and rising in shear-thinning fluid

The shape evolution of bubble formed in carboxymethylcellulose (CMC) aqueous solution was real-time observed using laser image technique. The flow fields of liquid around growing and rising bubble were measured by laser Doppler velocimetry (LDV), and the liquid mean velocity and its contour curves were obtained. The results show that bubble grows as spherical shape because of the dominant role of surface tension in the early period, and then is stretched gradually as a teardrop shape due to the common effect of buoyancy and shear-thinning of fluid. The axial mean velocity of liquid phase takes on Gaussian distribution with the symmetrical axis passing through orifice center. However, the radial mean velocity increases first and then decreases with the increase of the distance from measured point to the symmetrical axis above. Further, the axial component along symmetrical axis decreases initially and increases with the rise of height, as well as its corresponding contour map diverging gradually. The radial component, yet, decreases steadily with the rise of height, and the maximum value deviates towards the two sides until disappear, as it contour shape of butterfly’s “front wing”.

Fractal Approach to Bubble Rising Dynamics in Non-Newtonian Fluids

The Laser Doppler anemometry was employed to determine quantitatively the liquid velocity induced by the successive rising of single bubble in non-Newtonian carboxymethylcellulose (CMC) aqueous solutions under various experimental conditions of mass concentration solutions, measures heights and gas flow rate. The features of liquid motion in the region of bubble rising channel were investigated by analysis the liquid velocity pulsation using fractal theory. The results show that the liquid motion in the channel zone of bubble rise has a special feature of double fraction, and shows strong positive persistence characteristics for a small delay, but the positive persistence characteristics begins to reduce obviously with the increase of the delay, and even presents the anti-persistence for some measured points.

Agglomeration of soy protein isolate in a pulsed fluidized bed: Experimental study and process optimization

The soy protein isolate contains a high amount of protein and small fractions of fat, carbohydrates, and fiber. The food industry often employs this isolate as an additive, despite its drawbacks: it is a cohesive powder; its fluidization culminates in cracks and channeling. In this paper we used the experimental design to establish the optimal operational conditions to produce agglomerated soy protein isolate in a pulsed fluidized bed. The bed operated with an air pulsation frequency of 600rpm; the liquid binder consisted of an aqueous carboxymethyl cellulose solution. We employed a 23 complete factorial design with three central points to evaluate how the variables fluidizing air temperature (60–80°C), fluidizing air velocity (0.51–0.67ms−1), and binder flow rate (1.2–2.0mLmin−1) affected the mean particle diameter, process yield, and moisture content. Surface response analysis pointed out the operational parameters that provided large granules with low moisture content and high process yield. Compared with the raw isolate, the agglomerated particles were more porous and irregular; they also presented good handling properties, reduced wetting time and cohesiveness, and improved free-flow. Moreover, agglomeration enhanced the functional properties of the powder such as water retention and foaming capacity.

Influence of orifice spacing on twin bubbles formation in shear-thinning fluids: Laser image measurement

A laser image system for investigating the influence of orifice spacing on twin bubbles formation in shear-thinning fluid was established. The bubbles formation process at two orifices could be directly visualized and real-time recorded through computer by means of He–Ne laser as light source using the beam expanding and light amplification technology. The shape and size of bubbles generating in carboxymethylcellulose (CMC) aqueous solutions were studied experimentally at the orifices spacing 1Do, 2Do and 3Do (Do orifice diameter). The results reveal that the minute bubbles can be imaged clearly and amplified without distortion in the higher concentration solutions, and therefore the shape and size of bubbles are obtained accurately. With the increase of orifice spacing, bubble instantaneous volume in shear-thinning fluid decreases at the radial expansion stage but then increases at vertical elongation period, and the deformation and deviation of bubbles forming goes down due to the reduced interaction of adjacent bubble.

The Influence of Carboxy Methyl Cellulose (CMC) and Solution pH on Carbon Fiber Dispersion in White Cement Matrix

Dispersion of carbon fiber in cement matrix is one of main challenges for fabricating carbon fiber reinforced cement based materials. In this study, the dispersion of carbon fiber was improved by pre-dispersion of carbon fiber in basic aqueous solution using different concentrations of CMC. The relationships of CMC concentration and pH solution toward carbon fiber dispersion in aqueous solution was evaluated by UVvis spectroscopy. In order to understand how carbon fiber is dispersed in cement matrix, morphology fiber carbon reinforced composite was examined. Experimental results show that aqueous solution of CMC is effective to disperse carbon fiber. In addition, dispersion of carbon fiber increases with increasing of pH of CMC solution.

Nonlinear Analysis of Bubble Formation Dynamics in Shear-Thinning Fluids

The dynamics of bubble generating in carboxymethylcellulose (CMC) aqueous solution were studied using chaos method. The results show that for low position (P) and gas flowrate (Qg), the characteristic frequency of axial and radial velocities are both consistent to bubble periodic shear frequency; but for high position, power spectrums are of broad coverage within low frequency range. The magnitudes of radial characteristic peaks increase with gas flowrate. Phase portraits of reconstructed phase space of velocity time series display certain features of chaotic attractor. For lowPandQg, phase portrait takes on uniform elliptical shape due to liquid periodic motion caused by bubble periodic rising. Whereas for highPandQg, the liquid turbulence is reinforced by bubble increasing velocity and large-scale turbulent intensity around bubble increases, consequently, leading to significant compression of phase portrait.

Shock wave emission from a hemispherical cloud of bubbles in non-Newtonian fluids

Shock wave emission from a hemispherical cloud of bubbles, situated in non-Newtonian fluids, is investigated by high-speed photography, with up to 20million frames/s and an exposure time of 5ns, and acoustic measurements. The non-Newtonian fluids consist of a 0.5% polyacrylamide (PAM) aqueous solution, with a strong elastic component, and a 0.5% carboxymethylcellulose (CMC) aqueous solution, with a weak elastic component. In the relatively inelastic CMC solution, the maximum amplitude and the duration of the shock wave emitted during bubble cloud rebound are almost identical to the case of water. A significant reduction of the shock wave pressure was found in the elastic PAM solution. This difference ranges from a factor of 2, for a maximum radius of the bubble cloud Rmax≈800μm, up to a factor of 3, at Rmax≈270μm. A decrease of the shock wave duration was also observed in the elastic PAM solution. The observed reduction is attributed to an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive and to an increase of the cavitation threshold of the liquid. At a maximum radius of about 400μm, the shock pressure for a bubble cloud, situated in water and 0.5% CMC solution, is with a factor of six larger than the value measured in the case of individual cavitation bubbles. This difference is smaller in the case of a 0.5% PAM solution where the shock pressure for a bubble cloud is only three times larger than for a single bubble. The results are discussed with respect to cavitation erosion in polymer solutions and collateral effects in pulsed high-intensity focused ultrasound surgery, such as histotripsy used for the destruction of blood clots.