Fibrous solutions

CH rCHCH NHCSNH. Colourless crystalline solid with a faint garlic-like odour m.p. 74 C. Manufactured by treating propenyl isothiocyanate with a solution of ammonia in alcohol. It has been given by injection in the treatment of conditions associated with the formation of excessive fibrous tissue. Toxic side reactions may occur. Propenyl thiourea is a chemical sensitizer for photographic silver halide emulsions. 

The beater additive process starts with a very dilute aqueous slurry of fibrous nitrocellulose, kraft process woodpulp, and a stabilizer such as diphenylamine in a felting tank. A solution of resin such as poly(vinyl acetate) is added to the slurry of these components. The next step, felting, involves use of a fine metal screen in the shape of the inner dimensions of the final molded part. The screen is lowered into the slurry. A vacuum is appHed which causes the fibrous materials to be deposited on the form. The form is pulled out after a required thickness of felt is deposited, and the wet, low density felt removed from the form. The felt is then molded in a matched metal mold by the appHcation of heat and pressure which serves to remove moisture, set the resin, and press the fibers into near final shape (180—182). 

Cellulose Acetate. Almost all cellulose acetate, with the exception of fibrous triacetate, is prepared by a solution process employing sulfuric... 

Solution Process. With the exception of fibrous triacetate, practically all cellulose acetate is manufactured by a solution process using sulfuric acid catalyst with acetic anhydride in an acetic acid solvent. An excellent description of this process is given (85). In the process (Fig. 8), cellulose (ca 400 kg) is treated with ca 1200 kg acetic anhydride in 1600 kg acetic acid solvent and 28—40 kg sulfuric acid (7—10% based on cellulose) as catalyst. During the exothermic reaction, the temperature is controlled at 40—45°C to minimize cellulose degradation. After the reaction solution becomes clear and fiber-free and the desired viscosity has been achieved, sufficient aqueous acetic acid (60—70% acid) is added to destroy the excess anhydride and provide 10—15% free water for hydrolysis. At this point, the sulfuric acid catalyst may be partially neutralized with calcium, magnesium, or sodium salts for better control of product molecular weight. 

We have conducted the comparative study of gold (III), platinum (IV) and palladium (II) acidocomplexes solution on macroporous granular sorbents on the basis of polystyrene with functional groups of methyleneamine, 3-methylpyrasolyl, N,N-dimethylaminomethylene, dimethylmethylene-P-oxyethylamine and with functional 6-(3-methylpyridine) groups on polyvinylpyridine basis as well as fibrous polystyrene sorbent with pyrazolyl groups. 

Brasquet, C., Subrenat, E. and Le Cloirec, P., Selective adsorption on fibrous activated carbon of organics from aqueous solution Correlation between adsorption and moleeular strueture. Water Sci. Technol., 1997, 35(7), 251 259. 

Eisen-alaun, m. iron alum (ferric potassium sulfate), -amiant, m. (Iron) fibrous silica.. ammonaiauQ, m. ammonium ferric alum.. ammonaiaunldsuQg, /. solution of ammonium iron salt, esp. ammonium ferric alum. -antimonerZ) n., -antimonglanz, m. berthier-ite. 

Polymeric binder can be added to the network either as an aqueous latex dispersion or as a solution that should be dried prior to lamination in this process. In either case, the polymer should form a film and join adjacent fibers together and thus improve the stress transfer characteristics of the fibrous network. Provided that the proper film forming conditions are available, the property profile of the bonded network is determined to a significant degree by the properties of the polymeric binder at the temperature of use [20,22]. For example, if a softer type of product is desired, a binder with a relatively low glass transition temperature Tg) is often chosen. 

An effective method of NVF chemical modification is graft copolymerization [34,35]. This reaction is initiated by free radicals of the cellulose molecule. The cellulose is treated with an aqueous solution with selected ions and is exposed to a high-energy radiation. Then, the cellulose molecule cracks and radicals are formed. Afterwards, the radical sites of the cellulose are treated with a suitable solution (compatible with the polymer matrix), for example vinyl monomer [35] acrylonitrile [34], methyl methacrylate [47], polystyrene [41]. The resulting copolymer possesses properties characteristic of both fibrous cellulose and grafted polymer. 

Conventionally fillers are divided into reinforcing, active, and inert ones. The reinforcing class includes mainly fibrous materials. Disperse fillers may also perform the reinforcing function, and then they are called active. For the criterion of activity of a filler it has been proposed to employ, for example, the extent of variation of the relative viscosity of the melt or solution caused by introduction of a filler [23] — the greater the variation the better the affinity between the polymer and the filler. 

A characteristic feature of the structure of samples obtained under the conditions of molecular orientation is the presence of folded-chain crystals in addition to ECC. Kawai22 has emphasized that the process of crystallization from the melt under the conditions of molecular orientation can be regarded as a bicomponent crystallization in which, just as in the case of fibrous structures in the crystallization from solutions, the formation of crystals of the packet type (ECC) occurs in the initial stage followed by the crystallization with folding . 

Phillips, RJ Deen, WM Brady, JF, Hindered Transport in Fibrous Membranes and Gels Effect of Solute Size and Fiber Configuration, Journal of Colloid and Interface Science 139,363, 1990. 

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