This kind of removable adhesive wall hooks is commonly used at home. But how the little adhesive wall hook can hang 1kg or even heavier stuff? The secret is the cohesive force of the adhesive glue.
We have talked about the adhesion force of the glue from the last article.
Besides the adhesion force, the other important factor behind the stickiness of glue is its Cohesive Force.
When talking about cohesive force, it means the strength an adhesive’s inner bond holds tightly together on its own. The attractive force exists only between molecules of the same substance.
A “high” cohesive force is required for some adhesives to maintain a large amount of weight stably; otherwise, the adhesive will rip apart. The molecules of the adhesive must form a tight bond and bind on to one another. For example, sticky rice is pretty sticky, sometimes people will use sticky rice to adhere to stuff at the ancient time. However, things can not be strongly hung and hold on the wall well with sticky rice because the cohesive force of the sticky rice is relatively low to the adhesive.
The efficiency of bonding is determined by the good balance of adhesion and cohesive force. Some adhesives with good balance adhesion and cohesive force will make the paper substrate itself broken when peeling. If the glue stays only on one side of the substrate when peeling, that means the cohesive force is higher than adhesion. If the glue stays on both two sides of the substrate when peeling, that means the cohesive force is lower than adhesion.
As a result, the next time you use glue, you won’t look at it the same way you did before. You’ll be amazed by how an adhesive works in so many different ways.
For more knowledge about cohesive force please click here.