Testing Methods- Adhesion
Adhesion-
The ability of a tape to adhere, or stick to a substrate is called “peel adhesion”, and is a commonly used method. It gives a value of the attraction between the tape and the substrate, and the result is expressed in N/25 mm. The test is carried out by applying a strip of tape to a test panel with a roller of a specified weight. The tape is removed from the substrate at an angle of 90° or 180°. The test panels could be made from different materials such as glass, steel (high surface energy), HDPE (low surface energy), or the material being used in the actual application.
Peel Adhesion-
After the tape has been applied to the substrate, it is left for a specified dwell time, for example 10 minutes or 24 hours. The tape could also be exposed to different conditions to determine the influence on the bond, such as climate ageing (heat, cold, humidity), heat, UV-light and hot water.
After the dwell time, the tape and test panel is put in a Tensile testing machine, and the tape is pulled from the panel at a specified speed, normally 300 mm/minute.
Initial Adhesion or Tack-
The Initial adhesion or Tack is the flowing/wetting speed of the adhesive. The principle of the test is to apply the tape with a very light pressure to the test substrate and then immediately remove it and measure the force. There are two methods: The 90° peel and the “Loop Tack” and the result is expressed in N/25 mm. In the “Loop Tack”, the tape is formed to a loop, the loop lowered to the test substrate until it flattens out onto the surface. The motion is immediately reversed and the loop is separated from the substrate.