What is Peel Strength? Fundamentals Decoded

As a commoner, we have been underestimating the importance of peel strength. When I started interacting with industry specific people, I realise how damaging it could be if the seal of packing fails. And, the common reason behind such failures is poor peel strength. The properties of adhesives largely get affected by environmental conditions, like humidity. Peel adhesion is associated with the properties of the adhesive and its bonding strength to a substrate. Adhesives have many pressure sensitive applications like labels, duct tapes, etc. Their performance is evaluated on the basis how much force is required to detach from the surface. The strength required for peeling can be evaluated in two ways, how much force is required or another way round, it’s resistance to force applied. Some machines like peel strength tester are certainly used for such evaluations. 

Peel Strength - When we say peel strength, we are talking about three other factors altogether. They are, peel adhesion, shear resistance and tensile strength. According to industry standards, this strength is measured across the width of the tape. In this way, the resistance of the adhesion against separating force decreases. The strength varies depending upon the application. Like in temporary sealing, the strength should be balanced, not too high, to make it difficult to remove the tape; not too low, keeping the seal integrity in danger. Similarly, in permanent sealing, the resistance against the force should be maximum. Take the example of window frosting film. Here, we want the film to stick to the glass forever (not literally, but for a longer time).

Shear Resistance – You must have seen labels on the footwear. If we don’t remove this label manually, they would get removed itself due to external forces. First, they would get displaced from its position and then finally get detached. Here, the label experiences a parallel force to the bonding surface. The resistance of adhesion not get displaced from its position is Shear resistance. The Resistance of Adhesion against slipping.

Tensile Strength – Tension is the outward force applied on the adhesive tape is measured by peel strength tester. Sometimes, elongation is also used parallelly in the case of single-sided tapes. This becomes an important factor when both adhesive and substrate are non-flexible. And elongation becomes a considerable factor when either or both of them is flexible. However, the process of measuring both is same but their consideration varies with the application and material.

Presto offers a wide range of testing machines to test different parameters of adhesion under normal conditions and controlled conditions. For more information, contact us.