How to Test The Breathability of Stretch Film?
2022-07-13
The air permeability of Stretch Film is mainly expressed by air permeability and air permeability coefficient. Gas permeability refers to the volume of gas passing through the unit area of the tested membrane per unit time during stable permeation under the action of constant temperature and unit pressure difference; in the process of stable permeation, the unit thickness and unit area of the detected membrane per unit time volume of gas is penetrated. The air permeability test of the stretch film is carried out on a special instrument. The method is to separate the high pressure chamber and the low pressure chamber in the instrument with the measured film and seal it well. There is a test gas of about 105Pa in the high pressure chamber, and the volume of the low pressure chamber is known. At the beginning of the test, the air in the low-pressure chamber is evacuated with a vacuum pump, and the pressure is close to zero; The air permeability test of film stretch film should pay attention to the following points: 1. The temperature should be strictly controlled during the test. 2. The degassing and ventilation time is long during the tensile film test. Measurements of the pressure in the low pressure chamber should be recorded after stable penetration has been achieved. 3. The test and inspection process is carried out under the pressure difference between the high and low pressure chambers. Therefore, in order to ensure the accuracy of the test data, we must pay attention to the tightness of each system in the working instrument.
