Bond strength is a comprehensive measure of an adhesive's ability to hold two substrates together. It measures the resistance to separation and is affected by various factors, including the type of adhesive used, the bonding surface preparation, and the bonding process.
To fully understand the bond strength of an adhesive, it's necessary to understand the types of stress imparted on adhesive joints. The most common stresses include shear, peel, tensile, compression, and cleavage.
All these terms relate to the integrity of adhesive joints while measuring different strength aspects of the adhesive's performance. Below is a summary of each.
Shear strength measures an adhesive's resistance to forces parallel to the bonded surfaces. It represents the adhesive's ability to withstand pull directed across the adhesive, forcing the substrates to slide over each other. It is commonly tested by subjecting the bonded materials to a force applied parallel to the adhesive joint. A strong adhesive joint should exhibit both high bond and shear strength.