Oxygen permeability test of the hottest thin film

Thin film oxygen permeability test isobaric method (lower)

3. The test process of isobaric method

the test process of isobaric method is simple and clear (as shown in Figure 2, the blue pipeline is the test gas, the red pipeline is the nitrogen gas flow, and the flow direction is shown in the direction of the arrow). The plastic rope used in our life (begging rope in some places) is made of linear polyethylene or polypropylene. The test process can be divided into purging the zero point of the system, introducing oxygen flow into the upper chamber of the test, stabilizing the sensor output value (oxygen permeability) (judging that the penetration has reached equilibrium), and obtaining the test results. During the test, whether the nitrogen flow in the lower chamber is appropriate will directly affect the test result. When the standard tensile sample is in the tensile state, install an extensometer or stick a strain gauge on it. Therefore, with the help of the newly established fund, the isobaric oxygen permeating instrument has high requirements for nitrogen flow regulating devices and detection meters

after the test, first turn off the oxygen source, stop supplying oxygen to the upper chamber of the test, and adjust the system to the purge state (the nitrogen flow in the lower chamber bypasses the sensor). If the instrument needs to be tested in the near future, in order to prevent the reverse osmosis of Shangbu air into the system, the nitrogen flow can be adjusted to about 5ml/min to supply gas to the system for a long time. Of course, the sealing valve can also be closed. If the instrument is troublesome in the near future; For reuse, turn off the nitrogen source after sealing with the sealing valve

4. Isobaric method to detect the oxygen permeability of thin films

the use of isobaric method to detect the oxygen permeability of thin films has been widely used in the world. Some packaging and testing equipment manufacturers have launched their own isobaric oxygen permeability meters. Although they all follow the principle of isobaric method, the specific test steps, the performance of sensors, as well as the size and clamping of samples have their own characteristics

now take Labthink toy-c1 as an example to make a brief introduction: the size of the sample is medium 140mm. If the thickness of the sample is greater than 1mm, corresponding accessories should be added during clamping; Three chamber test can be carried out. In the process of clamping the sample, vacuum grease needs to be used to seal the edge of the sample, and attention should be paid not to allow the vacuum grease to pollute the test area (after the sample is clamped, it is shown in Figure 3); The test process is the same as the test process described previously

5. Outlook

isobaric oxygen permeability testing equipment has been very common in international trade, but China has not yet formulated the corresponding standards. However, with the acceleration of the internationalization of China's packaging industry, the isobaric test in China will also have a new look

from flexible packaging weekly