Permeability refers to a material's ability to allow a substance, such as a gas or vapor, to pass through it. It is an inherent property of the material and plays a crucial role in packaging applications. Materials with low permeability are ideal for preserving the shelf life of products by restricting oxygen and moisture ingress.
Two primary methods are employed for permeability testing, differential pressure method and sensor method.
Differential pressure method is widely used and involves creating a pressure difference across the test material. One side of the sample is exposed to the target gas or vapor at a higher concentration, while the other side is maintained at a lower concentration. Instruments employing this method typically measure the flow rate of the permeating substance across the material under a constant pressure difference.
Labthink C101B, C106H , C130H and VAC-V2 Gas Permeability Testers are developed based on the differential pressure method. These instruments measure the permeability of various gases like oxygen, carbon dioxide, and nitrogen. They are often automated and can analyze several samples simultaneously.
Sensor method utilizes sensors to detect the permeating gas or vapor directly. These sensors can be electrochemical or optical, depending on the specific gas being measured. While less common than the differential pressure method, sensor-based instruments offer advantages like faster testing times and higher sensitivity for certain gases.
Several factors influence the selection of a suitable test method and instrument, such as type of permeate, testing standards, material properties and testing conditions. In addition, temperature, humidity, and pressure conditions during testing significantly impact permeability values.
Permeability testing plays a vital role in material selection for packaging and other applications. Understanding the available test methods and instruments empowers researchers and manufacturers to evaluate the performance of materials in terms of gas and water vapor barrier properties. Careful consideration of permeate type, testing standards, material characteristics, and testing conditions is crucial for obtaining reliable and meaningful permeability data.
As the demand for functional packaging materials grows, testing methods are evolving to ensure a more comprehensive evaluation of packaging films. Labthink encourages collaboration with packaging industry companies for quality control! Visit the website www.labthink.com to learn more!
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