Adhesion is the bond strength measurement of a coating to a substrate. Many physical, mechanical and chemical forces come into play when an adhesive is bonded to an item or surface and these forces may have an effect on each other. Before a product can be used these effects need to be tested.
The use of structural adhesives has increased as more manufacturers realize their advantages compared to other types of joining techniques. The increased use of these adhesives, particularly where safety is important, necessitates the evaluation of any possible decrease in performance that may occur when glued joints are subjected to impacts.
90 Degree Peel Fixture
90 Degree Peel Fixture
Testing the adhesion properties is often associated with adhesives, tape, sealants, laminates, electronics, cosmetics, medical device packaging, general packaging seal strength and applications.
An example of this would be a 180 degree peel test for plastic film covering where low peel force films are often used to protect LCD screens and other surfaces that are scratch-prone. The force required to remove the film is very important. The bond must be strong enough to remain intact for product security but still easy to remove.
Testing at different temperatures can be done to simulate real world use for the materials.
Some of the more common test measurements include:
180 degree and 90 degree peel tests
Lap shear tests for evaluating the shear strength of adhesives
Coating cohesion - adhesion or bond strength of a coating to a substrate such as paints or varnishes
Seal strength, peel strength and adhesion strength tests to determine adhesion strength of flexible plastic packaging
ASTM D7234 - 12 Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers
ASTM D905 - 08e1 Standard Test Method for Strength Properties of Adhesive Bonds in Shear by Compression Loading
ASTM D3330- Standard Test Method for Peel Adhesion of Pressure Sensitive Tape
ASTM D906 - 98(2011) Standard Test Method for Strength Properties of Adhesives in Plywood Type Construction in Shear by Tension Loading
ASTM D1876 - 08 Standard Test Method for Peel Resistance of Adhesives (T-Peel Test)
ASTM D3807 - 98(2012) Standard Test Method for Strength Properties of Adhesives in Cleavage Peel by Tension Loading
ASTM D5868- Standard Test Method for Lap Shear Adhesion for Fiber Reinforced Plastic Bonding
ASTM D6862- Standard Test Method for 90 Degree Peel Resistance of Adhesives
ASTM D903- Standard Test Method for Peel or Stripping Strength of Adhesive Bonds