Cellulose solutions

Other patents (81,82) coveted the preparation of cellulose solutions using NMMO and speculated about their use as dialysis membranes, food casings (sausage skins), fibers, films, paper coatings, and nonwoven binders. NMMO emerged as the best of the amine oxides, and its commercial potential was demonstrated by American Enka (83,84). Others (85) have studied the cellulose-NMMO system in depth one paper indicates that further strength increases can be obtained by adding ammonium chloride or calcium chloride to the dope (86). 

Flammable liquids are widely used in many types of factories, and their misuse is responsible for many outbreaks of fire. The fire risks from the flammable liquids in common use such as petrol, paraffin, white spirit, cellulose solutions and thinners are well known, but these are only a few of the liquids which present hazards in industry. The variety of flammable liquids used in processes as solvents or carriers and for other purposes is constantly extending. 

The relative importance of the hafide anion - HO - Cell interactions can be inferred from application of the Taft-Kamlet-Abboud equation to the UV-Vis absorbance data of solvatochromic probes, dissolved in cellulose solutions in different solvent systems, including LiCl/DMAc and LiCl/N-methyl-2-pyrrolidinone [96]. According to this equation, the microscopic polarity measured by the indicator, Ej (indicator), in kcalmol is correlated with the properties of the solvents by Eq. 1 ... 

Another important aspects of solubilization are the physical state of the dissolved polymer as well as the thermo-chemistry and kinetics of the dissolution reaction. It is known that a clear cellulose solution is a necessary, but not sufficient condition for the success of derivatization. The reason is that the polymer may be present as an aggregate, as will be discussed below. Additionally, dissolution of activated cellulose requires less time at low temperature, e.g., 2 h at 40 °C, and more than 8 h at 70 °C [106]. These aspects will be commented on below. 

As indicated earlier, clear cellulose solutions are not necessarily molec-ularly dispersed they may contain aggregates of still ordered cellulose molecules [107]. The structure of these aggregates has been described in terms of a fringed micellar structure. Figure 2a shows a schematic possi-... 

In summary, although clear, light-colored cellulose solutions are required to start the synthesis, there is no guarantee, a priori, that the targeted DS will be obtained. The reasons are that the state of aggregation of cellulose is dependent on the structural characteristics of the starting material, is sensitive to the pre-treatment employed, and the impurities present. This may result in non-reproducible aggregation states, and may lead to oscillation in cellulose reactivity. Typically, effects of these oscillations may not be readily apparent, because ... 

As discussed above, solvatochromic data for cellulose solutions in liCl-DMAc indicate that Cl - HO - Cell hydrogen bonding is more important for dissolution than li-cellulose interactions. If decrystalUzation is rate Umiting, and considering that the eqiulibria shown in Eqs. 7 and 8 occur prior to decrys-... 

Kim, Y Morris, MD, Pulsed Field Capillary Electrophoresis of Multikilobase Length Nucleic Acids in Dilute Methyl Cellulose Solutions, Analytical Chemistry 66, 3081, 1994. 

No changes in lung histopathology or in lung weights were observed in rabbits exposed by gavage to 0, 100, 320, or 1,000 mg/kg/day hexachloroethane in methyl cellulose solution for 12 days (Weeks et al. 1979). 

There were no histopathological changes in the hearts of rabbits that were exposed by gavage to doses of 0, 100, 320, or 1,000 mg/kg/day hexachloroethane in methyl cellulose solution for 12 days (Weeks et al. 1979). This was also true for rats that were exposed to doses of up to 62 mg/kg/day in the diet for 16 weeks (Gorzinski et al. 1985) or rats exposed to doses of up to 750 mg/kg/day by gavage in com oil for 13 weeks... 

Hexachloroethane is apparently absorbed to a greater extent when administered in com oil than when administered in an aqueous medium, based on the fact that the LD50 values for hexachloroethane dissolved in methyl cellulose solution are higher than those for a com oil solvent in both male and female rats (Weeks et al. 1979). The ratio of LD50 values suggests that about one-third less material is absorbed from an aqueous medium. 

This is the first reported study of the spinning of mesomorphic cellulose solutions, but no fiber properties were given. Quenin et al. (14) used a d -jet, wet spinning system to spin cellulose/MMNO-H20 solutions. Fiber properties equiv dent to the best viscose rayon fiber were obtained. 

Sodium carboxymethylcellulose is formed by the reaction of sodium chloroacetate with basic cellulose solutions. The sodium form of carboxymethylcellulose is known as CMC or as a food grade product as cellulose gum. It is soluble in both hot and cold water. 

Cellulose dissolved in Schweitzer s reagent (cuprammonium) demonstrates strong laevo-rotatory optical activity. The optical activity of cellulose solutions differing in origin and of different morphological structure is the same. 

Detailed experiments on the osmotic pressure of cellulose solutions (Kratky and Musil [31]) have shown that the osmotic pressure of cellulose derivatives is subject to rules which do not differ from the laws for ideal solutions. The equation of osmotic pressure... 

Typical granulating liquids are gelatin or sodium carboxymethyl cellulose solutions. 

Inhibition Studies. A number of compounds were employed to study the amino acid residue(s) that are important for cellulase activity. Samples of enzyme (0.1 mL, 500 units) were pre-incubated with 0.1 mL of inhibitor in semimicroviscometers for 8 min at 35°C. CM-cellulose solution (0.8%, w/v), which had been separately equilibrated at 35°C for 20 min was added to the viscometers and initial viscosity losses were measured after 15 min. Inhibitors were replaced by buffer in control experiments. Compounds that are insoluble in buffer, e.g., N-ethylmalei-mide, diisopropyl fluorophosphate, and succinic anhydride, were dissolved in a small volume of 95% ethanol before assay. p-Chloromercuribenzoate (p-CMB) was first dissolved in 0.2M NaOH and the pH adjusted to eight prior to pre-incubation with cellulases. 

First Rimhock et al. [46] and later Francotte et al. [47-50] developed beads of benzoyl cellulose, which were found to be very effective for chiral resolution at the preparative scale. Benzoyl cellulose was dissolved in a mixture of dichloro-methane and heptanol and added dropwise to an aqueous solution of a surfactant (sodium lauryl sulfate), which is mechanically stirred at a well-defined speed. After addition of the benzoyl cellulose solution, stirring is maintained and the... 

A. Schumpe, W.D. Deckwer, Gas holdups, specific interfacial areas, and mass transfer coefficients of aerated carboxymethyl cellulose solutions in a bubble column, I EC Process Des. Develop. 21 (1982) 706-711. 

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