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　　The tension around the membrane is characterized by stretching and viscosity, which we are familiar with, but today's introduction is not these two effects. Another thing we ignore is its air permeability. Let's take a look at the common sense about the air permeability around the membrane.

　　The permeability of the surrounding membrane is mainly evaluated by gas permeability and good body permeability coefficient. Gas transmission refers to the volume of gas passing through the tested area around the membrane unit in unit time under the result of constant temperature and unit pressure difference; Gas transmission coefficient refers to the volume of gas passing through the tested membrane unit thickness and unit area in unit time under constant temperature and unit pressure difference

　　We can check the air permeability of the surrounding membrane through experiments, but we should study the methods when conducting experiments. At the same time, we should also pay attention to the following things:

　　1. The constant temperature shall be strictly controlled during the test.

　　2. It takes a long time for degassing and air permeability in the process of membrane test. The inspection of the pressure in the low-pressure chamber shall be recorded after reaching a stable penetration

　　3. The test inspection process is carried out under the premise of the pressure difference between the two high and low pressure chambers. Therefore, in order to ensure the accuracy of the test data around the membrane, it is necessary to pay attention to the tightness of each system in the operating instrument.

　　Article from: winding film manufacturer   http://www.refeel.cn