Fracture patterns in hot-melt adhesives

Different fracture patterns occur with hot-melt adhesives and other adhesives, which indicate different causes and conditions of failure. These fracture patterns are crucial for evaluating the strength and reliability of adhesive bonds.

Basic fracture patterns in their pure forms:

• Adhesive failure
• Cohesive failure
• Component failure

In practice, pure fractures occur less frequently. In many cases mixed fractures occur.

A mixed fracture consists of a combination of adhesive and cohesive failures. Loss of adhesion in some places and cohesive failure in other parts of the adhesive connection occur simultaneously.

Testing of adhesive connections can only be carried out in a destructive manner. When designing the bonds, the acting forces should be taken into account as a tensile movement. However, adhesive bonds are often tested using peeling methods. The various forces can produce different fracture patterns. Tensile movements tend to produce pure fracture patterns and peeling movements tend to create mixed fractures.

These fracture patterns are important indicators of the quality and reliability of adhesive bonds and help to identify weak points and optimise the bonding processes.