Permeability of film

When determining the permeability of films to water vapor, we seal a desiccant into a small cup with the polymer covering the opening. We weigh the cup before placing it in an oven at controlled temperature and humidity. After a given period of time we remove it and weigh it a second time. We calculate the film s water vapor transmission rate based on the area of the cup s mouth and the time that it was in the oven. 

Tomasula, P.M., Yee, W.C., Parris, N. Oxygen permeability of films made from CO2-precipitated casein and modified casein. J. Agric. Food Chem. 51, 634—639 (2003)... 

Sustained Releose - Fundamental information concerning membrane transport is likely to find ready application in the development of more effective forms of sustained release medication. The permeability of films composed of poly(methylvinylether)-maleic anhydride copolymer crosslinked with polysorbate 20 can be altered by an adjustment of the polysorbate 20 content, by varying the molecular weight oj the polymer, and by selecting the appropriate humidity pretreatment procedure... 

An additional problem is found in the differing temperature dependencies between the permeability of films to oxygen and carbon dioxide, and that of the respiration rate of the produce (Kader, A.A., personal communication). The effect of temperature on the respiration rate of some typical fresh produce has been tabulated (Inns, 1987 Kader et al., 1989). The effect of temperature on film permeability to oxygen has been plotted for several films (Robertson, 1991). 

Structural Small size of primary monocrystalline particles (-4-5 nm) Availability of variable sizes and narrow size fractions Different forms (i.e., particulate, coating/film, substrate) Large specific surface area (300 00 mVg) Low porosity/permeability of films High specific gravity (3.5 g/cm ... 

Table 97. Hydrogen permeabilities of film-forming materials (after Sager(se))... 

Rothe, W, and Groppenbacher, G., Permeability of film formulated with acrylic... 

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