ASTM D2578:09 pdf free download – Standard Test Method for Wetting Tension of Polyethylene and Polypropylene Films.
11.4 Proceeding in the direction indicated by the results of 11 .3, continue repeating 11 . I through 11 .3 until it is possible to select the ethyl Cellosolve-formamide mixture that comes nearest to wetting the film surface for exactly 2 s. The surface tension of this mixture in dynes per centimetre is called the wetting tension of the polyethylene or polypropylene film specimen.
Nom 8—Since the surface tension of the formamide/ethyl cellosolve solutions can change. for example. through evaporation of one or both components, or through contamination, and is dependent UOfl temperature. the actual surface elision of the solution that wet the film for exactly 2 s should be measured. This can be accomplished very simply with a surface ensiorncer.
11.5 Experience with this test has shown that on occasion erroneous wetting tension results can be obtained when the final wetting tension is determined by working progressively to lower surface tension mixtures when practicing 11.1-1 1 .4. It is recommended that the test analyst should check the reported wetting tension of the film by working progressively to higher surface tension mixtures.
12. Report
12.1 Report the average value of the wetting tension of each sample to the nearest 0.5 dynes/cm.
12.2 If the polyethylene or polypropylene film has been unevenly treated, it may not be possible to arrive at a single value of wetting tension. In this case, report the individual values whenever the largest value exceeds the smallest by more than 1 dyne/cm.
13. Precision and Bias
1 3. 1 Precision:
13.1.1 Table 2 is based on an interlaboratory study conducted in 1995 in accordance with Practice E69l involving three materials and thirteen laboratories. Each test result was the average of three individual determinations. Each laboratory obtained three test results for each material on two days.
13.1 .2 The values of the repeatability standard deviation Sr. reproducibility standard deviation SR. the 95 % repeatability and reproducibility limits on the difference between two test. The Fisher Surface Tensiometer. Model 20. has been found satisfactory for this annlicalion.
The results demonstrate that the precision of the results depends on the treatment level (wetting tension) of the film, the higher the treatment level, the higher the variability between single test results obtained in different laboratories, or the lower the precision.
13.1.3 Definitions.
Warning—The following explanations of r and R are only intended to present a meaningful way of considering the approximate precision of this test method. The data in Table 1 should not be rigorously applied to the acceptance or rejection of material, as those data are specific to the interlaboratory study and may not be representative of other lots, conditions, materials, or laboratories. Users of this test method should apply the principles outlined in Practice E691 to generate data specific to their laboratory and materials, or between specific laboratories. The principles 13.1.3-13.2 would then he valid for such data.