Transport and Solution of Water Vapor in Injection-Molded Polyethylene/Polyamide Sheets

• Published in: KOBUNSHI RONBUNSHU 1990/05/25, Vol.47(5), pp.425-431
• Main Authors: UYEDA, Tadashi, MISE, Kozo, ODANI, Hisashi, TAKAHASHI, Hideroh
• Format: Article
• Language: eng ; jpn
• Subjects: Diffusion Coefficient; Extremely High Shear Rate Processing; Injection Molding; Morphological Structure; Permeability Coefficient; Polyamide Blend; Polyethylene; Solubility Coefficient; Water Vapor
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.47.425

The transport and solution behavior of water vapor in polyethylene/polyamide blend sheets, which were obtained by injection molding under different shearing conditions, was studied at 30°C by the weighing method. The morphological structures of the blend sheets of various compositions were observed by scanning electron microscopy. In sheets prepared under extremely high shear rate conditions, the dispersed phases become shaped like fibers which are oriented in the direction of the flow. On the other hand, in sheets prepared with medium shear rate, sphere-like particles of various sizes disperse in the matrix. The solubility of water in the sheets was not affected much by the difference in morphological structure. The solubility coefficient increased with increasing the content of polyamide component. Apparent integral diffusion coefficients for sheets in which the fibrous domains are oriented in the plane sheet are greater than those for sheets having particle type morphological structure, if a comparison is made at the same composition of the blend. This was interpreted as mostly due to an effect of the preferential orientation of polymer chains. A synergistic effect was observed in the relationship between apparent permeability coefficient and composition in the region where polyamide domains disperse in polyethylene matrix. The effect was more pronounced for the samples which are obtained by extremely high shear rate processing.