DIN 55660-4:2012-04

This standard specifies a test procedure with optical methods for the determination of the polar and dispersive fractions of the surface tension of liquids. The procedure can be used for characterization of liquid coating materials. There may be limitations with regard to applicability in the case of liquids with non-Newtonian flow behaviour. This part of the standard assumes knowledge of the total surface tension of both the liquid to be tested as well as at least one suitable reference liquid. See in addition to DIN 55660-3, DIN EN 13470, DIN ISO 1409, amongst others, for procedures for determination. Principle: A drop from each fluid to be examined is produced hanging or rising at a cannula inside an optical cell which is nearly completely filled with reference fluid. The drop shall significantly deviate from the spherical shape due to its difference in weight in the reference fluid. The surface tension is calculated from the shape of the hanging or rising drop formed during the process according to the Young-Laplace equation. The determination of the polar and dispersive fractions of the surface tension of the liquid to be determined can be determined from the measured interfacial tension and the known surface tensions. The committee responsible for this standard is NA 002-00-07-15 AK "Kontaktwinkel/Benetzbarkeit" ("Contact angle/Wettability") at DIN.