Solvent drying, cellulose acetate

DEG and TEG are used as solvents for cellulose acetate derivatives and dyestuffs and as drying agents for refinery gases. 

Lui, A. Talbot, F.D.F Sourirajan, S. Fouda, A.E. Matsuura, T. Studies on gas transport through dry cellulose acetate membranes prepared by solvent exchange technique. Sep. Sci. Technol. 1988, 23, 1839. 

Uses Solvent for cellulose acetate fumigant and larvicide for tobacco, dried fruits, cereals, etc. cold-box foundry mold process curing agent intermediate for dimethylformamide, other org. synthesis in prep, of antileukemic agents... 

Sensitivity Towards Chemicals. The polymer may be sensitive to some chemicals (hydrocarbons, dehydration solvents such as glycols) or even water when in excess. For instance, the presence of excess liquid water can lead to the collapse of dried cellulose acetate membranes. That is why a pre-treatment of natural gas, such as a dew-pointing operation, is sometimes required before a membrane-based carbon dioxide removal operation. 

A variety of synthetic polymers, including polycarbonate resins, substituted olefins, and polyelectrolyte complexes, are employed as ultrafiltration membranes. Many of these membranes can be handled dry, have superior organic solvent resistance, and are less sensitive to temperature and pH than cellulose acetate, which is widely used in RO systems. 

In the simpler version of this method, a double based powder of small size is made by conventional solvent methods and thoroughly dried. The required amount of this powder is then placed in a beaker of cellulose acetate or ethyl cellulose and the voids are all filled with desensitised nitroglycerine. The curing process consists of heating to temperatures of the order of 80°C for a prolonged period and on cooling, the mass becomes a gelatinous body similar to cordite or ballistite. 

Uses Dry cleaning solvent for nitrocellulose, cellulose acetate, resins, oil, grease, albumin perfume fixative coating compositions for paper, cloth, leather lacquers. 

Uses Solvent for nitrocellulose and cellulose acetate artificial flavor for lemonades and essences fungicide and larvacide for cereals, tobacco, dried fruits acetone substitute organic synthesis. 

Uses Fumigant and larvacide for tobacco, cereals, dried fruits cellulose acetate solvent military poison gases intermediate in manufacture of pharmaceuticals, hydrocyanic acid, N,N-dimethylformamide organic synthesis. 

Relationship Between Nodular and Rejecting Layers. Nodular formation was conceived by Maler and Scheuerman (14) and was shown to exist in the skin structure of anisotropic cellulose acetate membranes by Schultz and Asunmaa ( ), who ion etched the skin to discover an assembly of close-packed, 188 A in diameter spheres. Resting (15) has identified this kind of micellar structure in dry cellulose ester reverse osmosis membranes, and Panar, et al. (16) has identified their existence in the polyamide derivatives. Our work has shown that nodules exist in most polymeric membranes cast into a nonsolvent bath, where gelation at the interface is caused by initial depletion of solvent, as shown in Case B, which follows restricted Inward contraction of the interfacial zone. This leads to a dispersed phase of micelles within a continuous phase (designated as "polymer-poor phase") composed of a mixture of solvents, coagulant, and a dissolved fraction of the polymer. The formation of such a skin is delineated in the scheme shown in Figure 11. 

All the coated samples listed in the tables were heated in an oven for 2 hours at 115 °C to ensure the removal of all solvent. Drying at room temperature, however, was sufficient for many of the coatings to pass the cellophane tape test. The cellulose acetate butyrate blends with 1% of each of the four carboxylated polyesters in Table II, for instance, passed the adhesion test on steel after the coatings had dried at 23 °C for only 0.5 hour, and the blends with 1% of the polyesters having acid numbers of 39-126 passed the adhesion test on aluminum. 

Most gas separation processes require that the selective membrane layer be extremely thin to achieve economical fluxes. Typical membrane thicknesses are less than 0.5 xm and often less than 0.1 xm. Early gas separation membranes [22] were adapted from the cellulose acetate membranes produced for reverse osmosis by the Loeb-Sourirajan phase separation process. These membranes are produced by precipitation in water the water must be removed before the membranes can be used to separate gases. However, the capillary forces generated as the liquid evaporates cause collapse of the finely microporous substrate of the cellulose acetate membrane, destroying its usefulness. This problem has been overcome by a solvent exchange process in which the water is first exchanged for an alcohol, then for hexane. The surface tension forces generated as liquid hexane is evaporated are much reduced, and a dry membrane is produced. Membranes produced by this method have been widely used by Grace (now GMS, a division of Kvaemer) and Separex (now a division of UOP) to separate carbon dioxide from methane in natural gas. 

Cellulosics cellulose, cellulose acetate, cellulose acetate butyrate, cellulose nitrate, cellulose propionate, ethyl cellulose Methanol, isopropanol 1. Abrasion. Grit or vapor blast or 220-grit emery cloth followed by solvent degreasing. 2. After procedure 1, dry the part at 100°C for 1 h and apply adhesive before the plastic cools to room temperature. For general-purpose bonding... 

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