Calcium thiocyanate system

In the study of Hannon and Wissbrun (10), which forms another point of departure for this work, a range of properties was investigated for the phenoxy-calcium thiocyanate system. The glass transition was observed to increase at a rate of 1.8°/mol % salt this, and the absence of negative deviations from additivity of specific volume, suggests that the interactions here are weaker than those in the systems studied by Moacanin and Cuddihy. The viscosity behavior reflected exclusively the increase in Tg. A strong shear-rate dependence of the viscosity was observed over the entire 40° range (170°-210°C) studied, and even at the lowest shear rates (3 X lO sec"1) the curves did not approach zero shear behavior. The samples could not be studied above 210 °C because of incipient decomposition. 

Aqueous salt solutions such as saturated 2inc chloride [7646-85-7] or calcium thiocyanate [2092-16-2] can dissolve limited amounts of cellulose (87). Two non-aqueous salt solutions are ammonium thiocyanate [1762-95-4]— uoamonia. and lithium chloride /744Z-4/A/—dimethyl acetamide [127-19-5]. Solutions up to about 15% can be made with these solvents. Trifluoroacetic acid [76-05-17—methylene chloride [75-09-2] and /V-methy1morpho1ine N-oxide [7529-22-8]—(92—94) are two other solvent systems that have been studied (95). 

Dubose found that mixtures of calcium thiocyanate and water would dissolve the cellulose [13]. This was the first solvent system for cellulose. Little work has been done on this solvent system because of its high propensity for thermal degradation of cellulose. Despite this problem, the solvent demonstrates many properties common to other direct solvent systems. 

The most important methods for the preparation of polyacrylonitrile are solution polymerization and suspension polymerization. The former method is particularly convenient, since when a solvent for the polymer is used, the resulting solution may be utilized directly for fibre spinning. Concentrated aqueous solutions of inorganic salts such as calcium thiocyanate, sodium perchlorate and zinc chloride make suitable solvents suitable organic solvents include dimethylacet amide, dime thy Iformamide and dimethylsulphoxide. Emulsion polymerization suffers from the disadvantage that the monomer has appreciable water-solubility and the formation of polymer in the aqueous phase can lead to coagulation of the latex. This tendency is reduced by the addition of ethylene dichloride to the system. 

Lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) was employed as a solvent for cellulose by McCormick et al. [83]. Turbak and coworkers were the first to spin cellulose fibers from this solvent system and studied the process extensively [84]. Patel and Gilbert were the first to report the lyotropic mesophase of cellulose in mixtures of trifluoroacetie acid (TFA) and chlorinated alkanes, such as 1,2-dichloroethane and methylene chloride [85]. Other solvents proposed for cellulose include ammonia (NH3)/ammonium thiocyanate (NH4SCN), calcium thiocyanate (Ca(SCN)2)/water, zinc chloride (ZnCl)/water, sodium hydroxide (NaOH)/urea [86], NaOH/thiourea [87, 88], and phosphorie aeid [89, 90]. 

Ammonium dimolybdate corrosion inhibitor, vapor-phase Dicyclohexylamine nitrite 2-Dimethylamino-2-methyl-1-propanol corrosion inhibitor, waterfloods Cocodiamine acetate Etidronic acid corrosion inhibitor, water systems Acrylic resin Hydrazine corrosion inhibitor, water treatment Ammonium dimolybdate Calcium oxide Etidronic acid Lauramine 2-Mercaptobenzothiazole Myristamine Myristamine acetate PEG-8 dioleate PEG-3 tallow aminopropylamine PEG-8 tallow aminopropylamine Potassium phosphate Potassium thiocyanate Potassium tripolyphosphate Sodium chromate Sodium molybdate dihydrate... 

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