Cellulose ethers commercial types

The two major commercial organosoluble cellulose ethers, ethyl-cellulose and ethyl(hydroxyethyl)cellulose (EHEC), are filmforming polymers distinguished by unusual properties and versatility (22). They contribute to the basic film properties of special types of inks, coatings, and adhesives. Their special utility results from the following performance properties (23) ... 

Method 1 (cellulose layers). The cellulose powder is washed twice with isopropanol-ammonium hydroxide-water (6 3 1), washed once in isopropanol and dried at 10S °C for 8 h. The plates (thickness, 0.25 mm) are prepared with a commercial TLC applicator. The slurry consists of 15 g of prepared cellulose in 85 ml of water which has been homogenized in a blender. The plates are dried at room temperature, and then eluted with diethyl ether in order to remove organic impurities. The plates are dried in air immediately before use. The pesticides are spotted and developed with appropriate solvent systems. The chromatoplate is dried in air and sprayed lightly with a 0.05% solution of fisetin in isopropanol. The separated spots are observed visually under a UV light at 365 nm (excitation, 370 nm emission, 533 nm). This method has been examined for several types of pesticides including carbamates, organophosphates, triazines and chlorinated hydrocarbons. 

Hypromellose phthalate is a cellulose in which some of the hydroxyl groups are replaced with methyl ethers, 2-hydro-xypropyl ethers, or phthalyl esters. Several different types of hypromellose phthalate are commercially available with molecular weights in the range 20 000-200 000. Typical average values are 80 000-130 000. ... 

Dialysis involves diffusion of solutes and fluids (e.g., water) through a semipermeable membrane separating out larger molecules and solid particles. Hie membranes employed are generally similar to the reverse osmosis or the nano-/ ultrafiltration type. Historically, dialysis has heen employed for various laboratory separations and commercially employed for NaOH or dilute sulfuric add recovery. The primary com-merdal application involves hemodialysis employed in artifidal kidney machines. Initially, cellulose and cellulose acetate membranes were employed, but polysulfone and poly (ether sulfone) are now in use with biocompatibiUty being a key membrane requirement. 

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