Feb
23
2019

Moisture Barrier Property Test of Aluminum Plastic Package for Milk Powder

Powdered milk or dried milk is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content.

In order to guarantee the quality of the milk powder within its shelf life, the barrier property (including oxygen barrier property and water vapor barrier property) should be considered when selecting packaging materials.

Currently there are mainly three categories of milk powder packages on the market. They are cans, bags and boxes. The cans are usually made of metals, which have the best barrier property among all packaging materials. The boxes are usually made of paper board, which have the worst barrier property. Plastic composite materials are usually used in the bags for mill powder, which will be elaborated in this article.

Aluminum or aluminized composite film, featured with ultra-high barrier property, is widely used as the packaging material for milk powder. However, the aluminum layer may be folded during package forming, product filling, heat sealing and transportation processes and as a result the barrier property (both oxygen barrier property and water vapor barrier property) may be compromised. Therefore it is necessary to test the water vapor permeability of aluminum plastic composite film after flex durability tests to guarantee its performance of protecting the milk powder from deliquescing and deterioration.

This article provides simplified testing procedures for moisture barrier property of aluminum plastic composite film for your reference.

Flex durability tests of specimens are performed according to ASTM 392. The specimens of flexible materials are flexed at standard atmospheric conditions (23°C and 50 % relative humidity), unless otherwise specified. Flexing conditions and number and severity of flexing strokes vary with the type of structure being tested. The flexing action consists of a twisting motion followed, in most cases, by a horizontal motion, thus, repeatedly twisting and crushing the film. The frequency is at a rate of 45cpm.

Then the water vapor permeability of the specimens after flex durability tests will be tested. There are two categories of test methods for water vapor transmission rate i.e. gravimetric method (also known as cup method and divided into dry cup method and wet cup method) and sensor method (including electrolytic sensor method, infrared sensor method and humidity sensor method).

Let’s take a look at the detailed testing procedures.

Step 1: Flex Durability Test

Mount the aluminum plastic composite film specimens in Labthink FDT-02 Flex Durability Tester and then perform full flex for 6 minutes i.e. 270 cycles. Condition the specimens after flex durability test (3 of each kind of specimen whose diameter should be 74mm) in the desiccant container at 23℃ for 48 hours.

Step 2: Water Vapor Transmission Rate Test

Add certain amount of distilled water into the test dish of Labthink W3/030 Water Vapor Transmission Rate Tester. Then mount the specimen in the mouth of the test dish. Place the test dish into the test chamber and close the door. Then set test parameters and start test. The test will be performed automatically and the test results will be given after test.

For more details about FDT-02 Flex Durability Tester and W3/030 Water Vapor Transmission Rate Tester, please visit www.labthink.com

About Labthink Instruments Co., Ltd:

Labthink Instruments Co., Ltd is one leading supplier of packaging testing instruments, which is headquartered in Jinan, China and operated in Boston, U.S.A.

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