Product packaging plays an important role in protecting product quality for the duration of its desired shelf life and providing packaged product stability. For moisture sensitive products, such as crackers, dry milk powers, prescription medicines, etc., moisture barriers materials are needed to control moisture into and out of packaging. It is essential to accurately test the barrier property, also called as water vapor transmission rate (WVTR).
There are two well-known ASTM test methods that described the measurement of WVTR for packaging materials:
ASTM E96 – Water Vapor Transmission of Materials Using Gravimetric Method (adopted in 1941)
ASTM 1249 – Water Vapor Transmission Rate Through Plastic Film Sheeting Using a Modulated Infrared Sensor (adopted in 1990).
ASTM E96 test method is also known as gravimetric or cup test. This method was developed in early 1940’s, when good barrier materials hadn’t developed at the time. For modern high barrier materials, this method is not sensitive enough to measure the results, or efficiently obtain results in a reasonable time period. The lowest detection limit is limited by the balance, usually only measures WVTR above 0.5 g/(m2*day) the best.
E96 is highly labor intensive and generally provides poor in-lab repeatability and reproducibility between labs. Test results from E96 method are also highly operator dependent. Due to the limitation of the sensitivity.
ASTM F1249 test method was Adopted in 1990. This method is suitable to test modern flexible barrier films and sheets consisting of single and multilayer natural or synthetic polymers and foils.
F1249 relies on instrumentation provided by the MOCON Permatran-W® product line, which includes a patented pressure-modulated infrared (PMIR) that can accurately detect down to one part per million (ppm) of water vapor. The lowest detection limit could be as low as 0.005 g/(m2*day). The newly developed PERMATRAN-W® Model 3/34 accurately generates and maintains desired RH.
F1249 has many clear advantages over E96, including precision, repeatability, accuracy and sensitivity.
F1249 can accurately differentiate barrier attributes of materials and packaging below the sensitivity limits of E96.
Testing repeatability is of great importance. F1249 eliminates operator-dependent variables for more accurate test results, and enables more informed packaging decisions.
F1249 test method takes much shorter to measure WVTR to equilibrium than E96 test method. By producing actionable results in less time, F1249 accelerates product and packaging development, and time to market is similarly reduced.
F1249 allows companies of all sizes to accomplish more with fewer labor resources and provides better, more precise results
F1249 provides more precise and repeatable WVTR testing data compared to E96, and provides that information in less time. Greater sensitivity provided by F1249 methodology ensures lab and business managers have the information they need to make packaging decisions that meet requirements in challenging environmental conditions globally.
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