BS ISO 19403-5:2015 pdf download – Paints and varnishes — Wettability — Part 5: Determination of the polar and dispersive fractions of the surface tension of liquids from contact angles measurements on a solid with only a disperse contribution to its surface energy

BS ISO 19403-5:2015 pdf download – Paints and varnishes — Wettability — Part 5: Determination of the polar and dispersive fractions of the surface tension of liquids from contact angles measurements on a solid with only a disperse contribution to its surface energy Step 5: The polar fraction of the surface tension of the liquid is calculated from the dispersive fraction of the surface tension and the surface tension measured in step 1. 4 Reference solid Sufficiently chemically and topologically homogenous dispersive solid, e.g. made of paraffin or PTFE. NOTE 1 For the application of this standard surfaces of solids with a polar fraction of < 0,5 mJ/m 2 are sufficiently dispersive. NOTE 2 Sufficiently homogenous PTFE reference surfaces preferably have a surface free energy of (18,5 ± 0,5) mJ/m 2 in accordance with the OWRK method, whereas locally measured surface free energies on the reference surface for the determination of the standard deviation (see 7.1) are measured in accordance with 6.3. For the PTFE surfaces as well as the paraffin surfaces precise reference objects with a mean roughness value R a 2) of less than 0,3 µm are to be preferred. The paraffin reference surfaces preferably have a surface free energy of (25,5 ± 0,5) mJ/m 2 under the same conditions as the PTFE reference surfaces. 5 Sampling Take a representative sample of the liquid to be tested in accordance with ISO 15528. 6 Procedure 6.1 Test conditions Carry out the test at (23 ± 2) °C and a relative humidity of (50 ± 5) % (see ISO 3270) and make sure that all test media have this temperature. 6.2 Determination of the surface tension of the liquid to be tested Measure the surface tension of the liquid to be tested in accordance with ISO 19403-3, EN 14370, or ISO 1409. 6.3 Determination of the surface free energy of the reference solid Measure the contact angle on the reference solid if unknown in accordance with ISO 19403-2. Use at least ten drops of each of at least three test liquids indicated in ISO 19403-2:YYYY-MM, Table 1, for this. Calculate the surface free energy of the reference solid in accordance with ISO 19403-2 in accordance with Owens, Wendt, Rabel and Kaelble or Wu. NOTE Since a reference solid with predominantly dispersive interactions is used it can be assumed that the dispersive fraction of the surface tension of the liquid can...