The barrier property of plastic film refers to the performance of the film on the permeability coefficient of small molecule liquid, gas, water vapor, odor and the like.
The barrier property of the plastic film is expressed by the transmission coefficient, and its unit is ml(g)·mm/m2·d·MPa, which means a plastic film product having a thickness of 1 mm, at a temperature of 23 ° C, a humidity of 60% RH, and a pressure of 1 MPa. The volume of cm 3 (ml) or mass g permeated through the small molecular substance per m2 area. It is usually based on three small molecules of O2, CO2 and water vapor.
The smaller the permeability coefficient of a material, the better its barrier properties. Generally, the permeability coefficient of the high barrier plastic film is less than 10 ml (g)·mm/m 2 ·d·MPa.
“High barrier” is undoubtedly an ideal property and one of the characteristics required for many polymer packaging materials. High barrier in technical terms means very low permeability to low molecular weight chemicals such as gases and organic compounds. High barrier packaging materials can effectively maintain the original properties of the product and extend the life of the product.
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