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Testing the permeability of stretch film

Source:Testing the permeability of stretch filmTime:2019-03-04Visitors:

The gas permeability of the stretched film is mainly expressed by the amount of gas permeation and the gas permeability coefficient. The gas permeation amount refers to the volume of gas per unit area of ​​the film to be tested per unit time when it is stably transmitted under constant temperature and unit pressure difference; the gas permeability coefficient refers to the constant temperature and unit pressure difference. When the transmission is stable, the unit thickness of the film to be tested and the volume of gas per unit area per unit time.

The gas permeability test of the stretched film is carried out on a special instrument by separating the high pressure chamber and the low pressure chamber in the instrument with the film to be tested and sealing. There is about 105 Pa of test gas in the high pressure chamber. The volume of the low pressure chamber is known. At the beginning of the test, the low pressure indoor air is first evacuated by a vacuum pump, and the pressure is close to zero. Then, the pressure riser of the low pressure chamber is detected by a manometer.

The following should be noted when detecting the gas permeability of the stretched film:

1. The temperature should be strictly controlled during the test.

2. Degassing and venting during the test process take a long time. The detection of the pressure in the low pressure chamber should be recorded after stable penetration.

3. The test inspection process is carried out under the condition of the pressure difference between the two high and low pressure chambers. Therefore, in order to ensure the accuracy of the test test data, it is necessary to pay attention to the sealing performance of each system in the work instrument.


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