Water vapor, sorption

WA Strickland, Jr., M Moss. Water vapor sorption and diffusion through hard gelatin capsules. J Pharm Sci 51 1002-1005, 1962. 

The effect of physical aging on the crystallization state and water vapor sorption behavior of amorphous non-solvated trehalose was studied [91]. It was found that annealing the amorphous substance at temperatures below the glass transition temperature caused nucleation in the sample that served to decrease the onset temperature of crystallization upon subsequent heating. Physical aging caused a decrease in the rate and extent of water vapor adsorption at low relative humidities, but water sorption could serve to remove the effects of physical aging due to a volume expansion that took place in conjunction with the adsorption process. 

Fig. 2 Water vapor sorption for recrystallized ( ) and ground ( ) sodium chloride at 20°C. (From Ref. 37.)...

Fig. 3 Water vapor sorption and desorption isotherms for ipratropium bromide at 20°C ( ), 2 month sorption (A), 5 month sorption ( ), 2 and 5 month desorption [Note All 2 month sorption results, except at 53% and 63% relative humidity, were verified at 5 months.]...

Fig. 4 Water vapor sorption ( ) and desorption (A) isotherms for microcrystalline cellulose at 20°C.-----, GAB fit to sorption data ------, GAB fit to desorption data.

Fig. 6 Water vapor sorption isotherms for poly(vinylpyrrolidone) at 60°C(+) 30°C (x) -20°C ( ) and -40°C (A). Data were taken from Oksanen and Zografi [71,75]. A 0 represents the calculated water contents necessary to depress Tg to the temperature of the isotherms.

M. J. Kontny, in Water Vapor Sorption Studies on Solid Surfaces, Ph.D. Thesis, University of Wisconsin—Madison, 1985. 

Spalt, H.A. (1958). The fundamentals of water vapor sorption by wood. Forest Products Journal, 8(10), 288-295. 

Mitrevej, A., and Hollenbeck, R.G., Photomicrographic analysis of water vapor sorption and swelling of selected super disintegrants, P/zarra. Tech., 6 48-50 (1982). 

In addition to providing a direct visualization of ionic clusters, the discovery of the thin fluorine-rich layer may have important implications with regard to the liquid/vapor sorption of these materials. To be sure, the nature of this layer would depend on the specific liquid or vapor environment contacting the membrane surface. In particular, the molecular polarity of the environment and its influence on surface tension would be involved. The difference between the liquid water versus saturated water vapor sorption was mentioned in this report. Also, the contact angle experiments of Zawodzinski et al. 

Mauritz and Rogers constructed a water vapor sorption isotherm model for ionomers with inherently clustered morphologies, as applied to Nafion mono-... 

Vishnyakov, A. Niemark, A. V. U. S. Army NSC Report Modeling of Microstructure and Water Vapor Sorption and Transfer in Permselective Membranes, 2000. 

Tsiapouris, A., Dresden, L. L. (2000). Water vapor sorption determination of starch based porous packaging materials. Starch, 52, 53-57. 

Berlin, E., Anderson, B. A. and Pallansch, M. J. 1968. Comparison of water vapor sorption by milk powder components. J. Dairy Sci. 51, 1912-1915. 

Vadas, E.B., Toma, P, and Zogra, G. (1991). Solid-state phase transitions initiated by water vapor sorption of crystalline L-660,711, a leukotriene PeceptorantagonislJharm. Res., 8 148-155. 

FIG. 1.—Water-vapor sorption-desorption hysteresis for maize starch at 40°C (from Ref. 19). 

Water activity may affect the properties of powdered dried product. Berlin et al. (1968) studied the effect of water vapor sorption on the porosity of milk powders. When the powders were equilibrated at 50 percent relative humidity (RH), the microporous structure was destroyed. The free fat content was considerably increased, which also indicates structural changes. 

Berlin, E., B.A. Anderson, and M.J. Pallansch. 1968. Effect of water vapor sorption on porosity of dehydrated dairy products. J. Dairy Sci. 51 668-672. 

Water vapor adsorption isotherms have been obtained on cotton from room temperature up to 150°C [303,304]. Theoretical models for explaining the water vapor sorption isotherms of cellulose have been reviewed [303]. Only adsorption theories will be discussed here at ambient temperatures. The shape of the isotherm indicates that multilayer adsorption occurs and thus the Brunauer, Emmett and Teller (BET) or the Guggenheim, Anderson and deBoer (GAB) theory can be applied. In fact, the BET equation can only be applied at relative vapor pressures (RVPs) below 0.5 and after modification up to a RVP of 0.8 [305]. The GAB equation, which was not discussed in the chapter in the book Cellulose Chemistry and Its Applications [303], can be applied up to RVPs above 0.9 [306]. Initially as the RVP... 

Water Vapor Sorption, Desorption, and Diffusion in Excised Skin Part I. Technique... 

Before describing the details of the new technique, we shall present a concise review of the most popular methods used to study water vapor sorption and permeability of the stratum comeum. 

Figure 6. Equilibrium water vapor sorption isotherms obtained on female stratum corneum (age 29) using salt solutions ( ) and the dynamic method (O) at 23.3 0.5°C...

Fig. 6 Water vapor sorption isotherm for crystalline and amorphous samples of indomethacin. ( ) Amorphous ( ) crystalline. (From Ref. " l)...

Hancock, B.C. Zografi, G. Effects of solid-state processing on water vapor sorption by aspirin. J. Pharm. Sci. 1996, 85 (2), 246-248. 

Chemisorption Solvation Curing of resins Water vapor sorption by excipients Curing of polymeric packaging materials... 

The three natural CDs form crystalline structures in the solid state that decompose above 200°C with no definite melting points. They are not considered hygroscopic, but they do form various stable hydrates. The water vapor sorption isotherms (Fig. 9) show two phases for the p- and y-CDs, and one phase for a-CD. At 11% RH, ot-CD absorbs 4 water molecules and upon long-term storage, forms a stable hydrate with 6 water molecules. The water content gradually increases with increasing humidity to a constant value of 6.6 water molecules per CD molecrJe at and above 79 /o Four different... 

Fig. 9 Water vapor sorption isotherms for a-, P-, and y-CD at 40 C. (Dashed line adsorption, solid line desorption). (Adapted from Ref...

Sadeghnejad, G.R. York, P. Stanley-Wood, N.G. Water vapour interaction with pharmaceutical cellulose powders. In Pharmaceutical Technology Drug Stability Rubenstein, M.H., Ed. Ellis Horwood Limited West Sussex, UK, 1989. Mitrevej, A. A Comprehensive Study of Water Vapor Sorption by Aspirin-Disintegrant Blends and its Relationship to Aspirin Stability. Ph.D. thesis, 1982. 

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