Permeability properties

Furthermore, Hildebrand and Scott [32] found a relationship between the solubility parameter, 5, and surface tension, as, for polar and non-polar liquids. Their relationship can be written as [66] 

Because of their low density, polymers are relatively permeable by gases and liquids. A more in-depth knowledge of permeability is necessary when dealing with packaging applications 

With polymeric materials these processes can occur only if the following rules are fulfilled  

In practical cases, such conditions are often not present. Nevertheless, this chapter shall start with these ideal cases, since they allow for useful estimates and serve as learning tools for these processes. 

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Permeability Different plastics provide different permeability properties. As an example polyethylene will pass wintergreen, hydrocarbons, and many other chemicals. It is used in certain cases for the separation of gases since it will pass one and block another. Chlorotrifluoroethylene and vinyli-dene fluoride, vinylidene chloride, polypropylene, EVA, and phenoxy merit evaluation (Chapter 4, PACKAGING, Permeability). 

Crowe, L.M. Crowe, J.H. (1986). Hydration-dependent phase transitions and permeability properties of biological membranes. In Membranes, Metabolism and Dry Organisms, ed. A.C. Leopold, pp. 210-30. Ithaca, N.Y. Comstock Publishing Associates. 

Papahadjopoulos, D., and Watkins, J. C. (1967). Phospholipid model membranes. II. Permeability properties of hydrated liquid crystals, Biochim. Biophys. Acta. 135. 639-652. 

Avdeef, A., Strafford, M., Block, E., Balogh, M. P., Chambliss, W., Khan, I. Drug absorption in vitro model filter-immobilized artifidal membranes 2. Studies of the permeability properties of lactones in Piper methysticum Forst. Eur.J. Pharm. Sci. 2001, 14, 271-280. 

G Wilson, IF Hassan, CJ Dix, I Williamson, R Shah, M Mackay. Transport and permeability properties of human Caco-2 cells An in vitro model of the intestinal epithelial cell barrier. J Controlled Release 11 25-40, 1990. 

I. Khan. Drug absorption in vitro model filter-immobilized artificial membranes. 2. Studies of the permeability properties of lactones in Piper methysticum Forst, Eur. 

F. Liu, M.J. Soares, and K.L. Audus. Permeability properties of monolayers of the human trophoblast cell line BeWo. Am I Physiol. 273 C1596-C1604 (1997). 

Papahadjopoulos D, Nir S, Oki S. Permeability properties of phospholipid membranes effect of cholesterol and temperature. Biochim Biophys Acta 1972 ... 

Permeability Properties of Cellulose Triacetate Hollow-Fiber Membranes for One-Pass Seawater Desalination... 

Heat Treated PVA Membranes. The concept of independent water and salt transport through PVA Is further supported by the permeability properties of heat treated PVA membranes. It was found that by subjecting the PVA membranes to heat treatment, a sharp decrease of the water and salt permeabilities Is caused. The... 

Strength, brittleness, and solvent permeability properties are limited because of lack of control of the ceramic composition on a macro- and microlevel. Even small particle sizes are large compared with the molecular level. There have been a number of attempts to produce uniform ceramic powders including the sol-gel synthesis in which processing involves a stable liquid medium, coprecipitation in which two or more ions are precipitated simultaneously. More recently, Carraher and Xu have used the thermal degradation of metal containing polymers to deposit metal atoms and oxides on a molecular level. 

In addition to these effects, there is much evidence to suggest that ozone significantly alters the permeability properties of cell membranes. In fact. Rich (JB) proposed that a primary... 

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