Moisture Barrier Property Test Method of Aluminized Film

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Aluminized film is one kind of high barrier packaging material, which is widely used in flexible plastic packaging industry. Aluminized film is plastic film coated with a thin layer of aluminum oxide. The common aluminized films include VMPET, VMCPP and VMBOPP, etc. Those aluminized films can be used as packaging material independently or laminated with other films to form aluminum laminated films.

The aluminum oxide coated on the surface of the plastic film is the key factor that determines the barrier property of the aluminized film, which is important to the quality assurance of the products paced with such packaging materials. Meanwhile the cost of aluminized film is low and that’s another reason why such packaging materials are more and more widely used in packages for coffee, milk powder, finger chips, tea, candy and pharmaceuticals, etc.

Generally, the barrier property of aluminized film is related to internal structure and thickness of the layer of aluminum oxide. As well, the manufacturing craft is another factor that may influence the barrier property of aluminized film. Sometimes, the barrier property of aluminized film may be compromised in high humidity environment owing to the destruction of the internal structure of aluminum oxide layer.

This article provides a simplified test method of moisture barrier property of aluminized film for your reference. The testing instrument is Labthink’s W3/330 Water Vapor Transmission Rate Test System.

Figure 1. Aluminized Films

There are mainly 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).

Labthink’s W3/330 Water Vapor Transmission Rate Test System employs electrolytic sensor in determination of water vapor transmission rate of flexible packaging materials. The gas transmission cell is designed in such way that, with the specimen inserted, it is divided into dry chamber and a controlled-humidity chamber. The dry side if swept by a flow of dry carrier gas, and water vapor permeating through the specimen from the controlled-humidity chamber is carried by the carrier gas into the electrolytic cell. Then the water vapor transmission rate can be determined by the electrolytic sensor.

The tests shall be performed according to the following procedures.

(1)    Cut 6 pieces of specimens from the provided sample material with sample cuter.

(2)    Take 3 pieces of specimens and mount them in the test cells with the aluminized surface facing towards high humidity side.

(3)    Set specimen thickness, test temperature, test humidity and other test parameters in the software interface.

(4)    Turn on the gas supply. Adjust the nitrogen gas flow rate and the pressure until the humidity inside the test chamber and the nitrogen flow rate reach specified values.

(5)    Click Test to start the test. The system will calculate and display the test results automatically.

(6)    Mount another 3 pieces of specimens in the test cells with the surface other than aluminized surface facing towards high humidity side. Repeat step 3 to step 5.

For more details about W3/330 Water Vapor Transmission Rate Test System, 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.