Permeation & Polymers

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66450 Bexbach

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Water vapor permeability WVTR (gravimetric) according to ASTM E-96


Water vapor permeability (gravimetric) ASTM E-96Description:

Testing method applicable to nearly all materials, e.g. plastic and polymer films, paper, cardboard, textiles with or without coating. The test can be run in desiccant or water method.

Result Unit:
WVTR (water vapour transmission rate) in grains/ft2*h (metric unit: g/m2*h = 1,435 grains/ft2*h;
related to the thickness: permeation coefficient P in g*mm/m2*h.

(Related) Standards:

DIN 53122-1 / DIN 53122-A,
DIN 53122-2 / DIN 53122-2-A,
ISO 2528:1995.

Test method:

A testing container's opening is covered by the sample. Using the desiccant method, it is filled with a desiccant that absorbs the water during the permeation time. Following the water method, the container is filled with water that evaporates through the specimen. The permeated amount of water is detected by weighing.

Detection limit:
Approximatively 0.01 g/m2*h. The detection limit also depends on the nature and thickness of the specimen. With a setup differing from the standard it is possible to measure much lower permeation rates. We will be glad to advice you individually. Proposed for a range of 1 - 200 g/m2*h, due to otherwise long enduring test times.

Required specimen:

For testing please send us a sheet of the approximate size of a sheet of paper (DIN A4, 210*297 mm).

For non flat specimens: please send after consulting us.

According to the standard, the testing area should be at least 30 cm2.

The specimens shall be uniform in thickness, representative for the material and free of pinholes and folds. On request we measure your sample thickness according to DIN 53370.

We recommend the measurement of three independent samples per test for samples with two identical sides. Otherwise two samples for each direction should be processed. Our standard is to measure samples of 20 µm - 3 mm, others on request.
Required sample dimension: we perform the preparation of the samples for you. For different test gases and type of samples we use differently sized samples.
If you want to conduct the cutting of the specimens yourself, please contact us for the required dimensions.

For sensistive coating test it sometimes makes sense to prepare first the support followed by the coating. Please inform us, if your samples tend to mechanical failure under applied pressure (of the test gas or the sealings).

Testing medium:

Water or water vapour.

It is possible to test with other substances in a similar way, e.g. with fuels.

Test conditions:

The standard is not restricted to a specific test temperature.

Mecadi's possible testing temperatures:

  • Standard -50 °C up to +150 °C,
  • other temperatures on request (-190°C up to 600 °C possible, requires set-up time)

Temperature tolerance possible with Mecadi equipment: better than +/- 0.1 K (target: +/- 0.01 K) Experience shows that +/- 1 K tolerance leads to permeation rate scattering up to 20 %.

The desiccant method can be carried out under different climate conditions.

Please contact us for information on special effects and requirements for the samples.

Also possible are temperature profiles (nonisothermic measurements) for determining morphology changes and the influence of media and moisture on polymer properties.

Based on this method, Mecadi offers further examination to determine gas solubilities (sorption and desorption), diffusion coefficients and the measurement of break through times through barriers.

Furthermore interactions between media and polymer can be investigated. Thus the predictions according resitance, physical and chemical reactions under process conditions can help in the selection process of materials.

You find this article here as a PDF. We also do the test sample manufacture for you.

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