This European Standard specifies the determination of the ability
of an adhesive to I1wetfa1 solid surface by- measuring the contact 7 angle and determining the critical surface tension of wettability. it allows the prediction of what adhesive will wet which adherend. It may be used tu characterize surfaces after priming, coating and bonding.
NOTE 1: In general the contact angle takes, in dependence on the proceeding motion of the borderline of the liquid (i.e. on the mode of application), a value between two borderline values,the advancing angle (e.g. after an extension of a drop) and the receding angle ( e.g. after a reduction of a drop) . Only if this differente between both, termed hysteresis- of contact angle, is negligible, the
contact angle expresses the critical surface tension defined in thermodynamics as a substrate-specific characteristic value. Normally, the hysteresis will not be negligible when the rugosities are above 0,5 pm and when the heterogeneous phase is not smaller than 0,1 Pm. The shape of the rugosity is essential for the hysteresis.
NOTE 2: For a comparison of wetting behaviour, the advancing angle should always be measured here.
Diese ÖNORM EN beschreibt ein Verfahren zur Bestimmung der "Benetzungs"-Fähigkeit eines Klebstoffes auf fester Oberfläche mittels Messung des Kontaktwinkels und der kritischen Oberflächenspannung. Es gestattet die Voraussage, welcher Klebstoff welchen Fügewerkstoff benetzt. Diese ÖNORM EN kann nur im Falle glatter und homogener Oberflächen angewandt werden, bei denen der Unterschied zwischen größer und kleiner werdendem Winkel vernachlässigbar ist (keine Kontaktwinkelhysterese).