Barrier properties of packaging materials

The barrier properties of packaging materials are often crucial for their applications. For the packaging of eg. fruit juices, the material has to be impermeable for water and oxygen in order to assure the quality of the product. The optimal gas conditions for a product packed in an equilibrium modified atmosphere packaging are achieved by selecting a packaging material with a suitable O₂ and CO₂ permeability. Paperboard is often coated to prevent diffusion of moisture into the board. In order to assess the performance of a packaging material, it is in general necessary to determine the barrier properties under realistic environmental conditions, like high relative humidities, and/or low temperatures. At EC-Pack, experimental facilities are available in order to study the gas- and water vapour permeability of films, paperboard or coated board under conditions which are encountered in ‘real life’.

O₂ permeability of (barrier) materials

A Mocon Oxtran 2/20 is used in order to measure the oxygen permeability of (barrier) materials ranging from 0.01 to 10,000 ml/m²·day·bar according to the ASTM D3985 norm. Measurements can be carried out between 10° and 40°C and at different relative humidities (0% RH, 30 – 85% RH).

The permeability for environmental gases ranging from 50 – 10⁵ ml/m²·day·bar can be determined with the diffusion measurement system developed by EC-Pack. Measurements can be carried out between 5 – 50°C and between 0% and 30 – 90% RH. Typical samples are packaging films, micro-perforated films, coated paper or paperboard. Experiments can be carried out in co- and counter-diffusion modes. In addition, the equipment can be extended to determine the permeability for other gaseous components.

Water Vapour Transmission (WVT)
WVT rates can be either determined gravimetrically according to ASTM E96 or using the humidity sensors of the diffusion measurement system, which are suited for determining the WVT rate according to the ISO 15106 norm. The latter technique is particularly suited for accurate and efficient measurements of WVT rates between 0.1 – 300 g/m²·day at different moisture gradients.

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