Hygroscopic properties

It is, therefore, required that all initial compounds be dried properly prior to performing the reduction. This procedure is not at all trivial and refers, first of all, to the diluent salts, and especially to potassium fluoride, KF, which is characterized by a strong hygroscopic property and a tendency to form stable crystal hydrates. The problem of contamination due to hydrolytic processes can usually be resolved in two manners. The first is to apply another tantalum-containing complex fluoride compound that does not undergo hydrolysis. The second involves the adjustment of the reduction process parameters and use of some additives that will "collect" the oxygen present, in the form of water, hydroxyl groups or other compounds. 

The surface wettability of heat-treated wood decreases due to a reduction in the hydroxyl content of the modified wood (Pdtrissans etal., 2003). There is a reduction in the water-sorption capacity, which is related to a reduction in the number of primary sorption sites (OH groups) within the wood cell wall, largely as a result of the removal/degradation of the hemicellulosic component. As remarked upon earlier, hygroscopic properties are strongly influenced by the treatment method employed. Podgorski etal. (2000) heated... 

Keith, C.T. and Chang, C.I. (1978). Properties of heat-darkened wood. I. Hygroscopic properties. Report, Eastern Forest Products Laboratory, Canada, No. OPX213E. 

Yano, H. and Minato, K. (1992). Improvement of the acoustic and hygroscopic properties of wood by a chemical treatment and application to the violin parts. Journal of the Acoustical Society of America, 92(3), 1222-1227. 

Together, antifreeze, PET, and polyester polymers account for about 98% of the ethylene glycol produced in the United States. It is also used sometimes as a deicer for aircraft surfaces. The two hydroxyl groups in the EG molecule also make EG suitable for the manufacture of surfactants and in latex paints. Other applications include hydraulic brake fluid, the manufacture of alkyd resins for surface coatings, and stabilizers for water dispersions of urea-formaldehyde and melamine-formaldehyde The hygroscopic properties (absorbs moisture from the air) make EG useful as a humectant for textile fibers, paper, leather, and adhesives treatment. 

Hameri, K., M. J. Rood, and H.-C. Hansson, Hygroscopic Properties of NaCl Aerosol Coated with Organic Compounds, . /. Aerosol Sci., 23, Suppl. 1, S437-S440 (1992). 

Hansson, H.-C., A. Wiedensohler, M. J. Rood, and D. S. Covert, Experimental Determination of the Hygroscopic Properties of Organically Coated Aerosol Particles, J. Aerosol Sci., 21, S241-S244 (1990). 

Weingartner, E., H. Burtscher, and U. Baltensperger, Hygroscopic Properties of Carbon and Diesel Soot Particles, Atmos. Environ, 31, 2311-2327 (1997). 

Urea is used in cream or ointment to make it less greasy, it increases the water content of stratum corneum which may be because of its hygroscopic property. It also possesses keratolytic property. 

TBAF has been modified structurally around the anion to reduce its hygroscopic property. Several such reagents have been reported and their reaction with organic halides and sulfonate esters have been described. Tetrabutylammonium difluoride is ascribed to be a stable reagent and easily displaces halides and sulfonate esters.215 1-Dodecyl tosylate (18) is thus converted into 1-fluorododecane (19) in 96% yield. 

Chan, M. N., and Chan, C. K. (2003). Hygroscopic properties of two model humic-like substances and their mixtures with inorganics of atmospheric importance. Environ. Sci. Technol. 37, 5109-5115. 

G. (2004). Hygroscopic properties of water-soluble matter and humic-like organics in atmospheric fine aerosol. Atmos. Chem. Phys. 4, 35-50. 

MUNITIONS - Unsuitable due to sensitive nature and hygroscopic properties... 

Noroin Ohlsson s Patent Dynamite consists of a mixture of ammonium nitrate, with 8 to 10 per cent, of pulverized charcoal or coal, and 10 to 30 per cent, of nitro-glycerine. The compound, which, on account of the hygroscopic property of the ammonium nitrate, must be kept in metallic cases or glass vessels, is exploded by means of a percussion cap. 

The hygroscopic properties of sulfate aerosols largely determine their specific weight. Depending on size, it varies from 1 to 2 g/cm . So, for instance, the mean bulk density of submicron particles substance is estimated in [41] at 1.37 g/cm and in [17] at (1.82-1.93) g/cm . 

Quantitative analysis, which is often difficult, requires reducing the size of the diffusing particles and diluting the sample in a matrix such as KCl. KCl is the most often used, in spite of its hygroscopic properties and its affinity for organic matter, because of the considerable penetration length of the beam in this matrix. 

Stratum corneum, the nonliving layer of skin, is refractory as a substrate for chemical reactions, hut it has a strong physical affinity for water. The chemical stability of stratum corneum is evident in its mechanical barriers which include insoluble cell membranes, matrix-embedded fibers, specialized junctions between cells, and intercellular cement. The hygroscopic properties of stratum corneum appear to reside in an 80 A-thick mixture of surface-active proteins and lipids that forms concentric hydrophilic interfaces about each fiber. This combination of structural features and surface-active properties can explain how stratum corneum retains body fluids and prevents disruption of living cells by environmental water or chemicals. 

Hygroscopic Substance. Perhaps the most distinctive and vitally important surface property of SC is its capacity to absorb up to six times its own weight in water (16, 89, 90). Attempts have been made to associate this property with protein surfaces (20, 91), protein-lipid interfaces (38, 63, 66), or with lipids alone (66, 92). Recently, investigators have emphasized the joint importance of lipids and proteins, or proteoglycan complexes, in hygroscopic properties (16, 66, 92). 

Figure 16. Demonstration of hygroscopic properties of cornified tissue and loss of such properties after extraction with pyridine and water. Adapted from Refs. 90 and 91.

---