Self-adhesive is a kind of bonding phenomenon, that is, the same kind of unvulcanized rubber is attached and placed in a fusion phenomenon after being placed for a certain period of time. This is the result of the mutual diffusion of rubber macromolecules on the two bonding surfaces through molecular thermal motion. The fastness of this bond is quite high, reaching several kilograms per centimeter, which means that there is adhesion on the surface to be bonded. This property is unique to unvulcanized rubber, the so-called self-adhesive.
Self-adhesive has advantages and disadvantages for rubber processing. The advantage is that it provides adhesive force for the adhesive type of each product to ensure the joint is firm. The disadvantage is that it does not need to be self-adhesive in some process steps, in order to prevent adhesion, it is also necessary to use a release agent.
The mechanism for forming self-adhesion is that when two unsulphurized rubbers having the same composition are in contact with each other, inter-molecular interdiffusion is generated by permeation at the interface, and after a period of time, the interface gradually disappears, and the two portions are integrated into one. Since the unvulcanized rubber macromolecule is slender and soft, when a certain segment moves due to bending, a segment is formed by the bending of the adjacent molecules, and a state in which the canine teeth are staggered is formed. When the result of the movement of numerous molecular segments at the interface accumulates to a certain stage, self-adhesion is formed.
