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Suggestions for Barrier Property Testing of High Transmission Rate Materials

Suggestions for Barrier Property Testing of High Transmission Rate Materials
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Suggestions for Barrier Property Testing of High Transmission Rate Materials - 1

Suggestions for Barrier Property Testing of High Transmission Rate Materials Abstract: based on experiences and material characteristics indicated in the barrier property testing for high barrier property materials, this article proposes corresponding operation suggestions for different barrier property testing items and methods, so as to better satisfy the testing demands for high transmission rate specimens with the common barrier property testing instruments. Key Words: high transmission rate, low barrier property, flow rate, concentration, testing area In some industries, certain transmission rates are required for specific applications. Handi-wrap and battery separator film are examples of low barrier property materials, which are also called high transmission rate materials. Owing to the special material characteristics, it’s ideal to apply specific testing instruments for transmission rate testing of high transmission rate materials. However, the applications are often new to the industries, and there are often no specific instruments for the new testing demands. Therefore, the already existing barrier property instruments have to be applied. The operators should bear in mind that when testing high transmission rate materials, they would show characteristics differing from medium and high barrier property materials. Moreover, fittings should be used in testing extremely high transmission rate materials for accurate and effective data. 1. Testing Characteristics for High Transmission Rate Materials High transmission rate materials have the following features in barrier property testing: first, the increased gas transmission quantities, which require a sufficient testing gas supply. Second, the larger gas flow rate, which requires the detective sensor to be more sensitive and be with broader measuring range. Third, there is no sufficient time for equilibrium determination. At present, tests for high barrier property specimens are emphasized; and there are still difficulties in testing high transmission rates specimens. It should be especially noted that the above-mentioned transmission equilibrium determination is the key point in barrier property testing. The conditions for determination should be strictly followed to avoid false judgment or even termination before reaching transmission equilibrium. As to medium and high barrier property specimens, several hours are needed for equilibrium. But for low barrier property materials, i.e., high transmission rate materials, such as non-woven and coated textile materials as well as battery separator films, they would achieve transmission equilibrium in a relatively very short period. That’s why the process of spacing sampling equilibrium determination has been deleted in water vapor transmission rate testing standards for textiles. For high transmission rate materials, the testing obstacles are mainly the increased gas transmission quantities and the greater gas flow rates. For example, the equilibrium determination for differential-pressure method gas transmission rate testing depends on gas pressure changing rate of the lower chamber. When purging testing gas into the upper chamber to test high transmission rate specimen, the pressure of the lower chamber would increase rapidly owing to the high transmission property of the specimen. As to equal pressure method gas transmission rate tester, the determination relies on oxygen concentration in the testing chamber, which would be directly measured by the sensor. However, when testing materials with extremely high transmission rates, the oxygen concentration in the testing chamber would go beyond the upper measuring range of the sensor and influence its life span. As to water vapor transmission rate testers, water vapor quantity going through the material would increase during the whole testing process. Therefore, great amount of solution consumption or exhaustion should www.labthinkinternational.com.cn

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Suggestions for Barrier Property Testing of High Transmission Rate Materials - 2

be avoided. At the same time, an effective control of ambient humidity should be emphasized. With a sufficient amount of testing experiences, the author summarizes the following suggestions that can help expand the measuring range and improve data repeatability when testing high transmission rate materials. 2. Gas Transmission Rate Testing for High Transmission Rate Materials 2.1 Differential Pressure Method The accuracy of differential pressure method testing is mainly decided by the data obtained from the pressure sensor in the lower chamber. When testing high transmission rate specimens,...

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Suggestions for Barrier Property Testing of High Transmission Rate Materials - 3

carefully observed. A certain amount of solution inside the cup after testing should be guaranteed, so as to avoid dried cup. If the cup cannot meet the requirement, bigger cups should be applied or customized. On the other hand, the humidity inside testing chamber should be carefully controlled. At present, Labthink PERME W series dish method instruments have the perfect capacity to automatically regulate humidity inside the testing chambers, which is advantageous in testing high transmission rate specimens. In order to enlarge measuring range, using MASK fittings to change testing area is...

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