DIN Determination of the water vapour transmission rate of plastic film, rubber sheeting, paper, board and other sheet materials by gravimetry. DIN Testing of plastics and elastomer films, paper, board and other sheet materials – Determination of water vapour transmission. DIN ENG_机械/仪表_工程科技_专业资料。Determination of the water vapour transmission rate of plastic film, rubber sheeting.
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In keeping with current practice in standards published by the International Organization for Standardization ISOa comma has been used throughout as the decimal marker. Two points are important in selecting the size 51322 dish, namely preventing the desiccant from becoming saturated during the test, on the one hand, and minimizing the total mass, on the other, to reduce its effect on the accuracy of weighing.
Water vapor permeability (electrolysis method) DIN / DIN A
Normalization of the water vapour transmission rate to a standard thickness is often required, but is possible only for homogeneous material, not for multilayer or laminated samples, and, of course, only in the case of an unaltered and essentially uniform material matrix.
If these conditions are fulfilled, the water vapour transmission rate, WVTR, of similar samples of different thickness is inversely proportional to the thickness, i. See DIN for other methods of determining water vapour transmission rates e. Amendments This standard differs from the November edition as follows.
Continued on pages 2 to 7. In case of doubt, the German-language original should be consulted as the authoritative text. All dimensions are in millimetres. Under refined test conditions e. These normative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision.
For undated references, the latest edition of the publication referred to applies. Since the water vapour transmission rate depends on factors that include the thickness and matrix of the sample material, it is not a material constant. Samples having a thickness greater than 3 mm shall be tested as specified in ISO The amount of water vapour that passes through the test area of the sample surface and is absorbed by the desiccant is determined by weighing the dish at regular intervals and recording the increase in mass.
They shall not exhibit any surface inhomogeneities e. If the two surfaces of the sample are not the same, the test area, i. If both surfaces of the sample are to be measured, twice the number of samples shall be prepared.
If the samples have been prepared using solvents, residues of the latter left in the sample may affect the test results. Details of any treatment of samples to remove the residual solvent shall be included in the test report.
Water vapor permeability WVTR (electrolysis method) according to DIN 53122-2 / DIN 53122-2-A
If the water vapour transmission rate is low, the thickness of the samples is large or the samples are very hygroscopic, one or two additional samples shall be prepared. Balance, capable of weighing to an accuracy of 0,1 mg.
Dib chamber, with a controlled atmosphere i. If this requirement cannot be satisfied because the samples have a high water vapour transmission rate, this shall be recorded in the test report. A desiccator as shown in figure 1, for example, in a controlled-temperature or air-conditioned room may be used as evaporation chamber.
In the case of highly transmissive samples, the number of dishes in the evaporation chamber may be kept low to ensure a ddin and uniform distribution of djn within the tolerances for the test atmosphere cin see subclause 8. Evaporation chamber without dishes shown in figure 2 or 3 NOTE 2: The relative humidity can be readily established in the desiccator by the solutions containing a large excess of salt specified in table 1. The internal depth of the dish should be between 8 mm and 24 mm, but shall preferably be 15 mm.
Aluminium dish Figure 3: The total water absorption of the agent shall not exceed 1,5 g per 25 cm3 during measurement. It is advantageous to 5312 material with a particle size of 1,5 mm to 2 mm that passes through a 4 mm sieve, has been freed of any fines using a 1,6 mm sieve, and has been dried in the normal manner. Sealant, consisting of a wax mixture that adheres strongly to both the dish and the sample, is not brittle dni the measuring temperature and is neither hygroscopic nor susceptible to oxidation.
It is advantageous to use a light metal lid that covers the dish when dkn is removed from the test atmosphere and weighed so that the sample releases as little water as possible to the dinn air during weighing.
This, however, is generally unnecessary in the case of non-hygroscopic film or sheets dn of those having low water vapour transmission rates. Cover templates of the type shown in figure 4 facilitate the sealing operation. Details of sealing samples 8 8. In the case of products having an outer layer, determine the mass per unit area as described in DIN Use one of the following atmospheres in the evaporation chamber: Use atmosphere B for rubber sheets, atmosphere D for plastic film and laminated paper, and atmospheres D and E for paper and board.
Then cover the dishes with the samples and firmly seal them to the dish wall, ensuring that the temperature of the sealant and any annular template used does not bring about any alteration in the dih. If the wax is spread out on the rims with the aid of a hot spatula, check that the seal is still intact after the sealant has cooled. Weigh the dish and sample and the lid if fitted to an accuracy of 0,1 mg, then place it in the evaporation chamber and remove the lid.
Check that the increase in mass between two consecutive weighings is at least 5 mg.
In blank tests, examine samples having low permeation rate and large thickness e. Make such blank samples in the same way and subject them to the same conditions, but without desiccant in the dishes. Subtract the blank values from the values measured for the ddin dishes having undergone the same treatment. This equation applies if the interval between consecutive weighings is 24 hours see subclause 8.
For other time intervals: Take the arithmetic mean of the individual values and report it to three significant places, but not to more than one decimal place. The same phenomenon will be observed if the humidity of the test atmosphere varies considerably during weighing.
It may also be due to sample defects and to differences in water dun transmission rates in the case of samples with single-side or even double-side lamination.
This can be remedied, for example, by increasing the mass of desiccant and repeating the test.