Carboxymethyl Cellulose Polymer Research Articles

Influence of polysaccharides on the creaming of casein-stabilized emulsions

The kinetics of creaming of concentrated oil-in-water emulsions made with sodium caseinate as emulsifier has been investigated at neutral pH as a function of the concentration of added polysaccharide using an ultrasound velocity scanning technique. Four different polysaccharides are studied: two microbial polysaccharides, xanthan and succinoglycan, and two carboxy-methylcellulose polymers of ‘medium’ and ‘high’ viscosity. A correlation is found between the relative stabilizing abilities of the polysaccharides and their rheological behaviour in solution at a polymer concentration of 0.25 wt%. A low concentration of each polymer leads to serum separation in emulsions of 10, 15 or 50 wt% oil. Stabilization of emulsions containing xanthan or succinoglycan at polymer concentrations of 0.25 wt% or above is associated with the formation of a gel-like emulsion structure with a significant yield stress. Surface viscosity measurement at a macroscopic oil-water interface provides evidence for weak interfacial interaction between casein and carboxymethylcellulose at the emulsion droplet surface. The implications of this for the mechanism of emulsion destabilization by polysaccharides are discussed.

Gut microflora of vervet and samango monkeys in relation to diet

The microflora in the gastrointestinal tracts of wild vervet and samango monkeys (Cercopithecus aethiops and C. mitis, respectively) were studied, using fermentation acid analysis, electron microscopy, and culturing methods. The diets of the two species of monkey differ considerably, with that of the samango including a greater proportion of cellulose-rich leaf material, and this is reflected in the microflora. Volatile fatty acid measurements along the gut of both species showed that these end products of bacterial metabolism were concentrated in the cecum and colon. Electron microscopy indicated that morphologically similar bacteria were present in the cecum and colon of both species, but the samango possessed a distinct stomach microflora. Bacteria in the lumina of the four main regions of the gut of the monkeys (stomach, small intestine, cecum, and colon) were plated on a number of anaerobic media (Mann, Rogosa, and Sharp; clostridial basal; and complex media). The cecum and colon were found to contain higher numbers of microbes per gram (wet weight) of gut content than the stomach and small intestine. Microbial isolates were able to catabolize carboxymethyl cellulose and other polymers. This may aid the monkeys, particularly samangos, in the digestion of fibrous dietary components such as leaves.

Flocculation of silica particles by adsorbing and non-adsorbing polymers

The stability of silica sols has been studied in the presence of adsorbing (hydroxyethyl cellulose) and non-adsorbing (sodium carboxymethyl cellulose and sodium polystyrene sulphonate) polymers. The state of aggregation has been monitored by turbidity measurements and for the adsorbing polymer, flocculation due to polymer bridging was observed at low polymer additions while at higher polymer concentrations flocculation induced by a depletion mechanism was observed for all samples studied. The critical polymer concentrations required to induce depletion flocculation were 0.2, 0.1 and 0.05% for hydroxyethyl cellulose (HEC), sodium carboxymethyl cellulose (CMC) and sodium polystyrene sulphonate (PSS), respectively. Varying the charge density of the CMC had no apparent effect on the critical polymer concentration required to induce flocculation.The pair potentials of the particles for the various systems have been calculated incorporating contributions from van der Waals, electrostatic, steric (for HEC) and depletion forces and the depth of the secondary minima in the energy curves have been used as an index for the onset of flocculation. A critical value for this minima of 5 kBT for the onset of flocculation was established from stability measurements determined using simple electrolyte. Good correlation was obtained between theory and experiment for HEC and PSS providing that values of osmotic pressure and radius of gyration of the latter were measured at the same solution ionic strength as in the silica dispersion. In the presence of CMC, however, flocculation was predicted to occur at 0.01% polymer which is an order of magnitude lower than the value found experimentally. These discrepancies may be due to the polydisperse nature of the CMC samples.

The Effect of Carboxymethyl Cellulose on the Flotation and Surface Properties of Graphite

The absorption behaviour of carboxymethyl cellulose polymers at the hydrophobic solid/aqueous interface has been studied using graphite as a model solid. The effect of the polymer molecular weight and concentration, the pH and ionic strength of solution on the surface properties of graphite have been established through the adsorption, electro-kinetic, and collectorless flotation measurements. The results have revealed a pronounced influence of surface impurities on the absorption of carboxymethyl cellulose onto graphite.

Isotachophoresis of synthetic ion-containing polymers : Characterization of the carboxymethyl distribution in carboxymethylcellulose

Isotachophoresis is used to evaluate the degree of substitution and the distribution of substitution of carboxymethyl groups in carboxymethylcellulose. Commercial samples ranged from very homogeneous to heterogeneous and included samples that appeared to be mixtures of carboxymethylcellulose polymers with different degrees of substitution. The measurements are made by separating the carboxymethylcellulose into zones inside a small capillary according to electrophoretic mobilities. The isotachophoretic separation mechanism is independent of polymer molecular weight. However, significant binding of counterions with the carboxyl groups is observed, which decreases the effective charge on fully neutralized carboxymethylcellulose. The extent of ion binding is proportionately higher for the polymer with higher degree of substitution, causing both shorter zone lengths and lower electrophoretic mobilities. This behavior conforms to generally accepted theoretical treatments for polyelectrolytes, resulting in isotachophoretic separations of carboxymethylcellulose that can be evaluated both quantitatively and qualitatively.

Drag Reduction in Flow of Coal-Oil Suspensions

Pipe flow characteristics of coal-oil mixtures (C.O.M.) are studied by a pipe flow facility consisting of a Tri-Rotor positive displacement pump, which draws fluid from a reservoir tank and discharges through a pipeline at regulated pressures. Pipe flow tests are carried out to study the drag reduction effect of the polymer carboxymethylcellulose (CMC) on the flow of coal-oil mixtures. Addition of CMC reduces friction drag on the average by 10 percent. Preliminary results are presented covering appropriate ranges of operating parameters (coal concentration and temperature) which influence the drag reduction. A brief discussion will evaluate the significance of these results.

Preface

Superabsorbent polymer (SAP) hydrogels are mainly acrylic based polymer hydrogels which are capable of absorbing water around 100 times of their own weight. Thus these are supposed to be the promising material which can be incorporated as a draw agent in forward osmosis (FO) process. In this paper, superabsorbent polymer hydrogels are used as a draw agent for protein enrichment in FO process so that structure of protein remains intact during dewatering process. Though the free swelling capacity of hydrogels in aqueous medium is high, due to their slow swelling rates water fluxes obtained in FO process are much lower as compared to conventional salts used as a draw solute. Thus in this paper research emphasis was given on increasing swelling rates of hydrogels to improve water fluxes by graft copolymerizing acrylic acid monomer on carboxymethyl cellulose (CMC) polymer. Moreover, for feasible recycling of these draw agents, a thermoresponsive polymer N-isopropyl acrylamide (NIPAM) was copolymerized with superabsorbing acrylic acid monomer and thermal dewatering process was used to regenerate the hydrogels.The synthesized hydrogels were tested as a draw agent in FO for bovine serum albumin (BSA) protein enrichment experiments. As the enrichment is directly related to the absolute weight of water extracted from the feed solution, the performance was presented in terms of enrichment factors. Thermally regenerated hydrogels were again recycled back to the process, and some reduction in enrichment was observed. Further based on the results obtained with different membrane area, mass of hydrogels, swelling ratios and water recovery rates, parameters for hydrogel assisted FO process are predicted for various applications.

Effect of drag-reducing additives on the rate of mass transfer in diffusion-controlled electrochemical processes

Mass transfer between a rotating cylinder and a solution containing sodium carboxymethyl cellulose polymer, was studied using an electrochemical technique involving the reduction of potassium ferricyanide in a large excess of sodium hydroxide. The Reynolds number and polymer concentration were varied over the ranges 4100–41 000 and 10–500 ppm, respectively. Under these conditions, it was found that polymer addition reduces the mass transfer coefficient by 10–22% depending on Reynolds number and polymer concentration. The mass transfer data in polymer-containing solutions were found to fit the equation (St) = 0.07(Re)−0.3(Sc)−0.644.

In Vitro Dissolution of Aceclofenac Loaded Hydrophilic Polymer Based Matrix Tablets and its Release Mechanism

Hydrophilic polymers are widely used to prepare sustained release matrix tablets. These polymers showed their sustained action by forming a barrier of thick gel layer around the matrix. Here swelling of the polymer and erosion of matrix plays a major role to control the release of the drug. In this present study the swelling and erosion properties of some hydrophilic polymers were correlated to their sustaining and rate controlling behavior. Matrix tablets containing hydroxypropyl methylcellulose (HPMC K100cps), carboxymethyl cellulose (CMC 50,000 cps) and methocel K15M CR polymers were prepared. The powder mixture was evaluated for their flow properties and the prepared tablets for their physical parameters. Swelling and erosion index of the tablets were carried out in pH 6.8 phosphate buffer and dissolution in 0.1N HCl (2 hours) followed by pH 6.8 phosphate buffer (8 hours) using USP apparatus II (paddle method) at 50 r.p.m. HPMC K100 cps was found to be not as rate retarding as the other two. From the all results it was observed that F-6 (containing 43.243% methocel K15M CR) showed highest swelling and erosion index (740.589% and 12.017% respectively), slowest release rate (24.491% at 8 hours) and highest MDT value (55.401 hours). Finally it can be concluded that increasing the polymer concentration or polymer's viscosity grade, swelling and erosion index increases, release rate decreases and MDT value increases. Key words: Aceclofenac; Matrix tablets; HPMC; CMC; Physical parameters; Release kinetics. DOI: 10.3329/bjsir.v45i2.5712Bangladesh J. Sci. Ind. Res. 45(2), 141-150, 2010

Effect of Carboxymethyl Cellulose on the Properties of Ordinary Portland Cement

Organic Polymer carboxymethyl cellulose (CMC) (0.25, 0.50 and 1.5% solution) was incorporated in Ordinary Portland Cement (OPC) and its effect on compressive strength, setting time, porosity, corrosive resistance, density and water absorbance have been studied. Organic polymer retards the setting time and a small increase in compressive strength was observed after 90 days for 0.5% CMC. Addition of polymer has been found to be effective in improving the acid resistance of OPC. Interaction of CMC with OPC causes decrease in water absorption, porosity and chemically bound water. X-ray diffraction of OPC-CMC pastes after 4 months and 1 year display some new peaks as well as disappearance of few peaks showing interaction of CMC with hydrated cementitious pastes. Examination of microstructure reveals that fibre types of matters were formed in hardened cement paste. Key words: Ordinary portland cement; Carboxymethyl cellulose (CMC); Compresssive strength; Porosity; XRD; SEM. DOI: 10.3329/bjsir.v45i1.5171 Bangladesh J. Sci. Ind. Res. 45(1), 1-8, 2010

The Surface of Cotton Fibers

Microscopical studies of surface replicas of chemically finished or modified cotton fibers have shown that the characteristic surface of native cotton is often altered by various commercial and experimental treatments. While removal of the wax from the fiber sur face has little effect, scouring usually uncovers the fine cellulose fibrils of the primary or even secondary walls. Mercerization does not eliminate the rugosities of the native fiber surface. Additive finishes, including starch, carboxymethyl cellulose, colloidal silica, and acrylic polymer resins change the original fiber topography to an extent dependent on the amount applied. In general, particulate additives tend to concentrate in the grooves of the fiber surface when applied in dilute formulations, but cover most of the fiber surface at higher concentrations. Chemical modifications which increase the fiber cross sectional area make the fiber surface smoother, hut extensive swelling of the cellulose derivative during its preparation appears to create roughness in some modifications. Crease resistant finishes do not alter the fiber topography significantly.