The ASTM D 5946 outlines the test method for measuring the water contact angle on corona-treated polymer films. It provides guidance on assessing the wettability of polymer surfaces, a property that affects their ability to retain inks, coatings, adhesives, and other substances.
ASTM D 5946: Application and Use
The wettability of a polymer film can be increased by several surface-treatments, such as the corona-treatment. An increased wettability means a better retention of inks, coatings, adhesives and other substances on the polymer films, which is important in many industrial applications. Contact angle measurements offer insights into the wettability of polymer films, or, in other words, into the effectiveness of different surface treatments.
The water contact angle describes the angle between a plane solid surface (the polymer film) and a liquid drop resting on this surface. ASTM D 5946 categorises the level of treatment into different ranges based on the water contact angle measurements.
ASTM D 5946: Experimentation
Apparatus
According to the ASTM D 5946, a water contact angle measurement can be conducted with a Contact Angle Meter, or Goniometer, which must include the following components:
- a liquid dispenser capable of suspending a droplet of the specified volume from its tip
- optionally, a sample holder
- provisions for bringing the sample in contact with the droplet in a controlled manner, and
- means for projecting an image of the drop contour
All Contact Angle Meters, or Goniometers, of the OCA series from DataPhysics Instruments comply with this standard.
Procedure and Calculation
In practice, the test method of the ASTM D 5946 involves placing droplets of water on the surface of a corona-treated polymer film, and subsequently measuring their contact angles.
The ASTM D 5946 is in use since 1999 and was last updated in 2017. Please note that it is identical to ISO 15989.
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