Carboxymethyl Hydroxyethyl Cellulose Research Articles

Determination of carboxymethyl substitution in cellulose ethers by Zeisel reaction and liquid chromatography

A new method has been developed for the determination of the carboxymethyl substitution in cellulose ethers. The carboxymethyl groups are cleaved using hydriodic acid with the formation of acetic acid. The acetic acid is quantitated using A Zorbax C/sub 8/ column with UV detection at 205 nm. Before quantitation, most of the iodide and iodine from the hydriodic acid must be removed due to their interference in the chromatography and detection. With the combination of oxidation and extraction, most of the iodide and iodine is removed. This method is applicable to the determination of carboxymethyl groups in the presence of other cellulose ether substituents. A model compound has shown reaction yields of +97%. The relative precision for 10 determinations at the 95% confidence level for a carboxymethyl cellulose (CMC) and a carboxymethyl hydroxyethyl cellulose (CMHEC) was found to be +/-2.4% and +/-3.0%, respectively. 12 references, 1 figure, 2 tables.

Evaluation of Acid-Gelling Agents for Use in Well Stimulation

Abstract Various polymers and other thickening agents have been evaluated as gelling agents for hydrochloric acid (HCl). These materials were compared on the basis of thickening efficiency, acid stability, and residue formation upon spending of the acid. Thickeners tested include xanthan polymers (XP), guar gum (GG), hydroxyethyl cellulose (HEC), carboxymethylhydroxyethyl cellulose (CMHEC), polyacrylamide (PAM), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), acrylamide/sodium-2-acryl-amido-2-methylpropane sulfonate copolymer (PAM/AMPS), and a cationic surfactant that thickens acid when used at high concentrations. Of the thickening agents tested, XP showed the greatest overall potential for use as an acid gelling agent. This polymer is an efficient viscosity builder and has good stability in 15% HCl at temperatures up to 150°F. Computer model studies, which take into consideration cool-down and gel degradation rate at various stages of acid spending, indicate viscosity is maintained when treating wells that have bottomhole temperatures (BHT's) up to 220°F. Since the gelled acid retains its viscosity during spending, both reaction rate and fluid leakoff are retarded. Laboratory studies simulating downhole spending conditions yield a 3.6-fold increase in spending time for gelled 15% HCl (22-cp) compared with ungelled acid. Well test results are presented that demonstrate the effectiveness of acid fracturing treatments using HCl with XP.

Investigation of a Cellulosic Polymer—Polyhydroxyl Polymer Interacted Polyelectrolyte System II. Polyhydroxyl Compound Binding and Preservative (Paraben Ester) Solubilization in CMHEC 43l–Polyethylene Glycol Systems

A dialysis study of carboxymethylhydroxyethyl cellulose and polyethylene glycol 200 and 400 in aqueous solutions with subsequent assay of the polyethylene glycol, showed substantial binding of the polyethylene glycol to the CMHEC, which increased with increasing concentrations of both components. A large increase in the solubility of the paraben esters determined by a solubility method and spectrophotometric assay was noted with CMHEC and polyethylene glycol 200, 400, and 4000. A bacteriological study of CMHEC and polyethylene glycol 200 and 400 with Aspergillis niger and Rhizopus nigricans showed that the increases in the solubility of the paraben esters affected the bacteriostatic properties of the systems studied. Adequate preservation of these systems with the paraben esters was obtained readily with concentrations of the paraben esters slightly above the total solubility in distilled water at 25° and much below the total solubility in the combination systems.