Breathable polymer material is spread by the dissolution and expansion caused two processes. Gas is first dissolved in the plastic material, the gaseous material then diffuses into the low concentration side and evaporated out. Factors will affect the amount of gas the molecular structure of the material, the thickness, the chemical nature and concentration diffusion media, as well as the ambient temperature, etc. permeable. Comparison of PE and permeability of certain plastics, PE of permeability decreases with increasing density, HDPE permeability much lower than LDPE. Compared with other varieties of plastic, PE of O2, N2, C02 and other air permeability larger, but low permeability to water vapor. Thus, PE film is not suitable for a long time the need to maintain the flavor of packaged goods, but the packaging is suitable for the need to prevent moisture or water vapor loss of items.
Various media on the permeability of PE to its solubility in the PE great relationship. Transmittance nonpolar media is greater than the polarity of the medium transmittance, the transmittance of the organic medium is greater than the transmittance of the inorganic medium, LDPE plastic bottles filled with different liquids will be different degrees of loss, therefore, LDPE plastic container not suitable for long-term storage of liquid, especially chemicals and oils, not only easy loss, but may also cause deformation of the container due to the swelling.
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