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Source: Link Testing Instruments Co.,Ltd.

When the army is marching, fighting, or performing special tasks, food is an indispensable and important supply to maintain the vitality of the troops and improve their combat effectiveness. Considering military strategy and material reserves, the shelf life of military food is generally more than 2 years, which requires its packaging materials to have excellent performance to ensure the quality of food during storage. In addition, the uncertainty of material supply methods and environmental conditions has put forward higher requirements for packaging materials. Among them, moisture resistance is one of the important properties of military food packaging and is a key factor affecting the amount of water vapor in the environment that penetrates into the packaging. Moisture is a necessary condition for the growth and reproduction of microorganisms. Therefore, when there is more moisture in contact with food, it is not only easy to absorb moisture, agglomerate, and soften the skin, but also increases the risk of mildew. The use of packaging materials with high barrier properties to water vapor (i.e. excellent moisture resistance) can significantly reduce the amount of water vapor that penetrates into the packaging, which plays an important role in preventing food from spoiling.

Reducing volume and weight are the basic characteristics of military food. With the advancement of packaging technology and the development of polymer materials, military food packaging has gradually transitioned from tinplate cans to soft plastic composite bags and tubes. The water vapor permeability of soft plastic packaging materials of different materials is not the same. In order to ensure the quality of military food during storage, it is necessary to strengthen the detection and monitoring of the moisture-proof performance of such materials.

 

Test philosophy  and Test Instruments

The test adopts the principle of infrared to test the moisture-proof performance of the sample. The test basis is ASTM F1249 "Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor". The LTWTC-303H water vapor transmission rate test system produced by Link Testing Instruments Co.,Ltd. is used as the test equipment to test the water vapor transmission rate of the sample.

LTWTC-303H Water Vapor Transmission Rate Tester

 

The LTWTC-303H water vapor transmission rate test system is based on the test principle of infrared moisture analysis sensor, and is designed and manufactured in accordance with ASTM F1249 and ISO 15106-2 standards. It provides a wide range and high-efficiency water vapor transmission rate test for medium and high water vapor barrier materials. It is suitable for water vapor transmission performance testing of films, sheets, paper, packaging and related materials in the fields of food, medicine, medical equipment, daily chemicals, photovoltaic electronics, etc.

 

Test sample and test process Test sample: Take a certain aluminum-plastic composite film for military food packaging as the test sample to test its water vapor transmission rate.

Test process:

1. Sample cutting - Use a special sampler to cut 3 samples from the sample to be tested.
2. Sample loading - Apply vacuum grease on the surface of the three test chambers of the equipment, install the 3 samples on the three test chambers respectively, and clamp them with clamping devices respectively to ensure that the seal between the sample and the test chamber is good.
3. Test - Set the sample name, sample thickness, test mode, test temperature, humidity and other parameter information, turn on the gas source, adjust the nitrogen pressure, make the humidity in the test chamber reach the set value, and rotate the carrier gas flow adjustment switchto make the nitrogen flow in the upper and lower chambers meet the standard requirements. Click the test option and the test starts. The equipment performs the test according to the set parameters and displays the test results after the test.

 

Test results and analysis:

The water vapor permeability of the three samples tested in this experiment were 0.079 g/(m2·24h), 0.083 g/(m2·24h), and 0.088 g/(m2·24h), respectively. The water vapor permeability of the aluminum-plastic composite film sample was the average of the test results of the three samples, which was 0.083 g/(m2·24h).

 

Water vapor transmission rate is an important parameter indicator for measuring the moisture-proof performance of military food packaging, which directly affects the quality of food during its shelf life.

For more details please visit www.linktesting.org