The ability of an adhesive joint to withstand a sudden load is of interest in a wide variety of applications. The automotive and the electronics industries are just two of the major adhesive markets that place a high value on impact resistance. In the auto industry this is called "crash worthiness". As a result, a variety of adhesive formulations have been developed to provide improved toughness and impact resistance, and a range of test methods have been devised for applying rapid loads.
Impact resistance of structural adhesives has been discussed thoroughly in several previous SpecialChem articles.1,2 There are a number of impact tests that are commonly used and widely recommended for adhesives. However, all have shown various limitations, related mainly to the difficulty in setting up the specimen and the need to attach the impact apparatus rigidly to a stiff and heavy base.
This article will discuss a relatively new test to measure the impact resistance of an adhesive - the impact wedge peel test.