How to detect the breathability of the stretch film
The air permeability of the stretched film is mainly indicated by the Air perm and the gas permeation coefficient. The Air perm refers to the unit volume of gas passing through the unit area of the detected film in unit time under the steady temperature and unit pressure; the gas permeation coefficient refers to the gas flow coefficient at the steady temperature and the unit pressure. At the beginning of the experiment, take the air Out from low pressure chamber result the pressure to near zero; then use a pressure gauge to check the pressure change in the low pressure chamber.
In doing the stretch film permeability test should pay attention to the following matters:
1, the experiment to strictly control the temperature stability.
2, the process of degassing, ventilation are needs a long time, Check the pressure in the low pressure chamber should be recorded after reaching the stabilization.
3, The test procedure was carried out in two high and low pressure chambers, so, in order to ensure the accuracy of the test data, we must pay attention to the sealing of each system from the operating instrument.