Calcium chloride dihydrate saturated

Chitosan has also been used to prepare coated or bicomponent filaments. A chitosan-coated alginate filament was successfully prepared by the addition of a small amount of chitosan to the first coagulation bath containing the calcium chloride dihydrate saturated methanol solution. Touch and feel as well as mechanical properties of the alginate filament were improved by... 

Solvents known to dissolve chitin are a mixture of formic acid and dichloroacetic acid, a mixture of trichloroacetic acid and dichloroethane, a mixture of dimethylacetamide and lithium chloride, methane sulfonic acid, calcium chloride dihydrate saturated methanol, and 10% sodium hydroxide solution [4], Chitosan is much more soluble than chitin. It dissolves in aqueous solutions of many organic and inorganic acids. 

FIGURE 2.14 The first derivative UV/Vis absorption spectrum of a-chitin (100 mg/ 100 mL) dissolved in saturated solution of calcium chloride dihydrate in methanol. 

Chitin sheets are excellent for use in biomedical devices due to their biodegradability and lack of toxicity. These sheets can be prepared by simple procedures. A solution of a-chitin, in saturated calcium chloride dihydrate-methanol solvent system, is dropped into excess of distilled water with gentle mixing to desolubilize the ot-chitin the obtained chitin hydrogel is decanted several times with distilled water and filtered. ot-Chitin sheets are obtained after the evaporation of water. 

These three equations represent saturation with respect to the hexahydrate, tetrahydrate, and dihydrate in the temperature ranges indicated. The phase relationships among calcium chloride, its hydrates, and a saturated solution are illustrated in the diagram in Figure 1. 

From a pure, saturated solution of calcium sulfate the dihydrate CaSO ZHjO crystallizes if the temperature is below 60°G. If the crystaUization occurs at a higher temperature the anhydrous salt GaSO is formed. From common seawater, with its high content of sodium chloride, anhydrous calcium sulfate may also be formed at temperatures down to 30°G [14.3]. During geological periods these processes have occurred in nature and formed the minerals gypsum, the dihydrate, and anhydrite, anhydrous calcium sulfate. 

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