Introduction of test methods for gas permeability of gel films

Abstract: Gas permeability is an important index parameter that affects the performance of gel films. This article introduces how to use the pressure difference method to test the gas permeability of the gel film through the test of the oxygen permeability of the gel film and the description of the test process, test principle, equipment parameters and scope of application. Use performance monitoring to provide a reference.

Keywords: gas permeability, oxygen permeability, gas permeability meter, differential pressure method, gel membrane

1. Significance

Gel membrane is a widely used polymer material, which is used in gas separation, biotechnology, medical, electronics, automotive and other industries. Proper permeability and selective permeability are important for the wide application of gel membrane One of the conditions. For example, the gel membrane used for gas separation should have high selectivity and high permeability; the gel membrane used for the microbial carrier should be able to provide the oxygen required to maintain the normal activity of the microorganisms on the basis of ensuring that no microorganisms leak; In therapeutic applications, the gel film reduces the evaporation of microvascular and collagen fiber water vapor and oxygen supply, reducing scar regeneration. Therefore, by detecting the gas permeation of the gel membrane and understanding the gas permeability of the gel membrane in time, it can provide an effective data basis for the control and improvement of the performance of the gel membrane. This article takes the test process of the oxygen permeability of the gel film as an example to introduce the detection method of the gas permeability of this kind of material.

2. Test samples

This experiment tested the oxygen permeability of a certain gel membrane material.

3. Test basis

The testing methods for the oxygen permeability of materials are mainly divided into two principles: differential pressure method and equal pressure method. In view of the fact that the differential pressure method can test many types of gases, such as oxygen, nitrogen, carbon dioxide, air, etc., this test uses the differential pressure method principle Test the oxygen permeability of the gel membrane sample according to the standard GB / T 1038-2000 "Test method for gas permeability of plastic films and sheets with differential pressure method".

4. Test equipment

This test uses the VAC-V2 differential pressure method gas permeameter to test the samples. The equipment is independently developed and produced by Jinan Languang Electromechanical Technology Co., Ltd.

Figure 1 VAC-V2 differential pressure method gas permeameter

4.1 Test principle The differential pressure method is to obtain the gas permeability of the sample according to the change of the infiltration gas pressure with the infiltration time. The clamped sample divides the test chamber of the device into a high-pressure chamber and a low-pressure chamber. The high-pressure chamber is filled with a certain pressure of the gas to be tested, and the low-pressure chamber is vacuumed to form a low-pressure environment. During the test, the gas penetrated from the high-pressure chamber to the low-pressure chamber through the sample under the effect of the pressure difference. The pressure in the low-pressure chamber gradually increased. The penetration time has a linear relationship, and the gas permeation amount of the sample is calculated by measuring the change value of the pressure in the low-pressure chamber per unit time at this time. Because the sensor in this method monitors the pressure of the permeated gas, the type of gas that can be tested is not limited, and it can be used to test a variety of gas permeability.
4.2 The test range of equipment parameters is 0.05 ~ 50000 cm3 / (m2 • 24h • 0.1MPa), the vacuum resolution can reach 0.1 Pa; the temperature control range is 5 ℃ ~ 95 ℃, the temperature control accuracy is ± 0.1 ℃; the humidity control range is 0% RH, 2% RH ~ 98.5% RH, 100% RH, the humidity control accuracy is ± 1% RH, which can meet the testing needs of customers under different test conditions; three completely independent test chambers can test three of the same Or different samples; data fitting at any temperature can be performed to easily obtain test results under extreme test conditions; after restructuring, this device can also support the testing of toxic gases, flammable and explosive gases; provide standard membranes for rapid Calibration to ensure the accuracy and versatility of test data; support LystemTM laboratory data sharing system, unified management of test results and test reports.
4.3 Scope of application It is professionally used for testing the gas permeability, permeability coefficient, solubility coefficient and diffusion coefficient of various film and sheet samples at various temperatures. Films include various plastic films, paper-plastic composite films, coextruded films, aluminized films, aluminum foil, aluminum foil composite films and other film-like materials; sheet materials include various engineering plastics, rubber, building materials and other sheet-like materials, such as PP Sheet, PVC sheet, PVDC sheet. It can be extended to the air permeability test of aerospace materials, paper and paperboard, paint film, fiberglass cloth, fiberglass paper, cosmetic hose sheet, various rubber sheets and other materials.
It is suitable for the transmission test of various gases, such as oxygen, carbon dioxide, nitrogen, helium, air, etc. Can meet a number of national and international standards, such as ISO 15105-1, ISO 2556, GB / T 1038, ASTM D1434, JIS K7126-1, YBB00082003, etc.

5. Test process

(1) From the surface of the sample to be measured, cut three samples with a size greater than 7 cm in diameter.

(2) Apply a layer of vacuum grease on the periphery of the three test chambers of the equipment. Place a piece of filter paper in each test area, paste the cut samples on the three test chambers, and clamp with the clamping device.

(3) Set the sample information such as sample name, material, thickness and other test control parameters such as test mode and vacuum time. Click the "Start Test" option to start the test and turn on the vacuum pump.

(4) The device performs an automatic test according to the set control parameters. After the test, the device calculates and displays the test result based on the measured pressure change of the low-pressure chamber with time.

6. Test results

The test results of the three samples measured in this test are 64.0591 cm3 / (m2 · 24h · 0.1MPa), 69.3381 cm3 / (m2 · 24h · 0.1MPa), 65.8406 cm3 / (m2 · 24h · 0.1MPa), The oxygen permeability of the tested gel film is the average value of the test result 66.4126 cm3 / (m2 · 24h · 0.1MPa).

7. Conclusion

Gas permeability is an important performance index of gel membrane materials. This article uses the differential pressure method to test the oxygen permeability of the gel film samples. The test process is simple, the equipment is easy to operate, the test efficiency is high, and the test results have high precision and accuracy. It can accurately and quickly test the oxygen barrier of the sample. performance. In addition to oxygen, this device can also be used to test the permeability of thin films or sheet materials to various gases such as nitrogen, carbon dioxide, air, helium, sulfur hexafluoride, etc., and has a very high cost performance. Jinan Languang Electromechanical Technology Co., Ltd. is a high-tech enterprise specializing in R & D, production and packaging inspection services of packaging inspection equipment. It is always committed to providing customers with high-end, accurate, intimate and efficient equipment and services. The more you understand, the more you trust! Labthink looks forward to enhancing technical communication and cooperation with enterprises and institutions in the industry.

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