ABSTRACT
A sealant is a special type of adhesive which is used in joints undergoing substantial dimensional changes. The sealant accommodates the joint movements and prevents moisture and dirt from entering the joint. In order to fulfil its function, the sealant needs to adhere to the substrate. Wherever two different materials come in contact, an interphase is formed. The strength of this interphase plays a significant role in the overall performance of the joint. Typical sealant adhesion tests require cohesive failure in the sealant as the most important indicator of a strong bond. However, this evaluation criterion only ensures that, under certain test conditions, the cohesive strength of the sealant is weaker than its adhesive strength. It does not evaluate the actual bond strength. On the other hand, a careful study of the interfacial failure can be very useful for understanding the durability of the sealant/substrate bond. This paper discusses some recent adhesion test methods which attempt to measure the strength of the interphase formed in a sealant joint.
