Efflorescent, definition

Polymerization products with internal plasticization have the advantage that there is no migration or efflorescence of the plasticizer on storage. On the other hand, the mechanical properties—above all, flexibility at low temperatures—are decreased in comparison with the products with low molecular plasticizers. This is because mobility in the solvatized molecules is diminished. The same refers to tensile strength, which is often decreased with internally plasticized polymers. In this respect they are inferior to externally plasticized products, which also have an advantage in that type and quantity of plasticizer can be varied widely. Internally plasticized products must have a definite ratio of components. These are reasons why combinations of both types of plasticizers are preferred. 

The dodecahydrate is efflorescent at room temperature in air. At 22° C. it becomes damp and the dampness increases as the temperature rises until finally the salt becomes completely liquid. A definite melting point is not exhibited.3 The liquid becomes clear at 56 2° C. and is then a true solution of the heptahydrate. When this is supercooled to about 40° C. and seeded with a crystal of the salt, crystals of the heptahydrate are deposited and the temperature rises to 56-2° C. A similar evolution of heat, but less marked, occurs at 22° C. The heptahydrate does not effloresce appreciably at room temperature in air. 

Substances that are ordinarily deliquescent are sulfuric add (concentrated), glycerol, calcium chloride crystals, sodium hydroxide (solid), and 100% ethyl alcohol. In an enclosed space, these substances deplete the water vapor present to a definite degree. Other substances are used to accomplish this end by chemical reaction, e.g.. phosphorus pentoxide (forming phosphoric acid), and boron trioxide (forming boric acid). Water is absorbed from nonmiscible liquids by addition of such substances as anhydrous sodium sulfate, potassium carbonate, anhydrous calcium chloride. and solid sodium hydroxide. The converse phenomenon is known as efflorescence. 

This change which is known as efflorescence is caused by loss of water of hydration from the crystal, leaving either the anhydrous salt or a less hydrated salt (of definite composition, however). Every crystal hydrate has a definite vapor pressure at a given temperature. If this vapor pressure is greater than the partial pressure of the water vapor in the air the crystal hydrate will lose water to the air. This will continue until all the water is lost or equilibrium between the water vapor in the air and in the hydrate is reached. 

Hexahydrate, efflorescent, triclinic-rhombohedral prisms, d 1.786. mp 53°. Loses water on storage at Kf, becomes definitely anhydr at 100°. d (anhydr) 2.49. One gram dissolves in 4.5 ml water. Insol in ale. LD orally in mice ... 

C. The syrup immediately solidifies to a slurry of fine, white needles of TlCl 4 H3O on cooling in an ice bath, larger crystals form on slower cooling. The crystals are rapidly filtered and dried 24 hours over HgSO and KOH (virtually no efflorescence). Cushman claims that TICI3 4 H3O crystals can only be dried between filter papers if loss of water is to be avoided. Hecht states that he found no definite tetrahydrates. 

In Ippen s (1978) case of contact eczema, the epicutaneous test, with isoniazid as substance or as pulverized tablets (from several manufacturers), showed in all instances definite eczema reactions which exceeded the test areas and required local treatment with corticosteroids. Wang and Schmeo (1974) report the case of a patient with occupational allergy to isoniazid. Beside the allergic reaction of the immediate type (asthma bronchiale) there was a latent sensitization of the delayed reaction type (eczema reaction). This latent sensitization was manifested in a circumscribed area by the epicutaneous test. Reexposure to the allergen led to an asthmatic spasm of the bronchi and to recrudescence of the eczematous cutaneous efflorescences when it was inhaled. 

Definition Commercial prod. Is the monohydrate Empiricai C2K2O4 C2K2O4 H2O Formuia (COOK)2 H2O Properties M.w. 166.22 Monohydrate Colorless transparent cryst. odorless sol. in water efflorescent in warm dry air dec. when heated m.w. 184.24 dens. 2.13 loses water 160 C Toxicoiogy LDLo (oral, woman) 1 g/kg toxic by inh. and ing. human systemic effects by ing. (cardiac arrhythmias, shock, Gl changes) ... 

Definition Phosphoric acid, disodium salt Empirical HNa204P 7H2O Formula Na2HP04 7H2O Properties Colorless orwh. gran. effloresces in warm dry air sol. in water insol. in alcohol m.w. 268.07... 

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