Water vapour transmission properties of free polymer films

Abstract

The water vapour transmission properties of selected hydrophilic, lipophilic, and mixed hydrophilic‐lipophilic polymer systems, cast as free films, have been examined as a function of time, film thickness, plasticiser concentration, and film formulation. An inverse linear relationship was established between the logarithm of the water vapour transmission rate (Rwvt) and the logarithm of film thickness in the presence of the various plasticiser concentrations for the three systems studied. The lipophilic n‐butyl methacrylate films were found to be less permeable to moisture than either the hydrophilic hydroxypropyl cellulose or mixed methyl hydroxypropyl cellulose‐ethyl cellulose films. The butyl methacrylate films closely follow Fickian diffusion, whereas the permeability constants of the other two films increased linearly with film thickness over the range of thicknesses studied. These phenomena are discussed with respect to the relative attractions these films have for water vapour.

Monomolecular Film Properties of Protective and Enteric Film Formers II: Evaporation Resistance and Interactions with Plasticizers of Poly (Methyl Vinyl Ether/Maleic Anhydride)

“…Increasing the concentration of plasticizer in the film caused first a decrease, and then an increase in water vapor permeation. Banker et al (36) obtained similar results with films of hydroxypropyl cellulose and poly(buty1 methacrylate). It was postulated by Lachman and Drubulis that plasticizer fills the interstices of the polymer, reducing permeation.…”

Water vapour permeability, thermal and wetting properties of whey protein isolate based edible films

“…Banker, Gore, and Swarbrick (1966) reported a similar slight decrease in the water transfer rate or flux, but an increase in WVP values, with increasing thickness of hydroxycellulose films (range 40-260 mm). McHugh et al (1993) and Gennadios, Weller, Cole, and Gooding (1994) tried to explain the effect of the thickness on the permeability of hydrophilic films by introducing a modification to the calculation of the WVP.…”

Development and application of polysaccharide–lipid edible coating to extend shelf-life of dry bakery products

“…Various hypotheses have been proposed to explain the increase in WVP with increasing film thickness. Barrer (1951) and Banker, Gore, and Swarbrick (1966) attributed the thickness effect to film swelling as a result of water-film interaction. Recently, other Authors McHugh et al, 1993) observed that as film thickness increased, the film offered enhanced resistance to water vapor transfer across it.…”