Use of Water Contact Angle Measurements for Corona-Treated Polymer Films is done by ASTM D5946. The surface characteristics of a polymer film decide how well the polymer films can retain the surface coatings. The contact angle of a water droplet on the polymer film surface indicates its ability to accept and retain surface coatings.
Water Contact Angle Measurements by ASTM D5946 for surface-treated polymers. Surface coating substances like inks, paints, adhesives, and clear coats are applied on polymers films to make decorative inscriptions and graphics on automobiles and electronic items.The capability of polymer films to retain these surface coating substances is primarily dependent on the surface characteristics of the polymer films. Some surface-treating techniques can improve surface characteristics. One of such techniques is Corona treatment, an electrical discharge treatment, able to increase the wetting tension of a polymer film. The contact angle of a water droplet on the polymer film surface gives a fair idea about its ability to accept and retain surface coatings.
In contact angle measurements by ASTM D5946, a strip of the polymer test material is placed on the Goniometer testing platform. A syringe on top puts on a single drop of deionized water over the polymer specimen. The goniometer gauge displays an enlarged projection of the water drop. This gauge is adjusted to measure the angle between the material and the edge of the water drop.
Specimen strips of 15 mm (0.5 inches) length and breadth with a thickness of a maximum of 2.5 mm are used for contact angle measurements test by ASTM D5946.
The test result is provided as an angular measurement in degrees. This angle in degrees is then converted into the surface energy for purified DI water with the help of the table provided in ASTM D5946.