Difference Between Adhesive and Cohesive

Adhesive Vs Cohesive

Adhesive and cohesive are as confusing as distinguishing cohesion from adhesion. Both words (adhesive and cohesive) are actually adjectives that describe something. Cohesive can describe an organization or group as in the case of a cohesive organization. This would mean that the group is unified and well integrated. Adhesive bandages describe the bandage as sticky.

Another technical difference with adhesive is that it can also be considered as a noun aside from being an adjective. Any substance, which is able to adhere things or two surfaces to each other, like how glue and cement are able to stick certain materials, can be termed as an adhesive.

In the realm of Physics or Chemistry nonetheless, the two may pertain to certain attractive forces as in cohesive force and adhesive force. In either subjects, cohesive forces exist between similar molecules (intermolecular attraction) while adhesive forces exist between unlike molecules or bodies (intramolecular attraction).

Adhesive force may pertain to the attractive strength that binds the adhesive to a substrate. The adhesive is able to adhere to the surface of the substrate because of the adhesive force. This force is a result of a plethora of molecular interactions between two or more materials. In the process, there are the so-called weak and strong bonds. In the former, there is hydrogen sharing (hydrogen bonding) while in the latter there are two probabilities: one being a sharing of atoms (covalent bonding) and the other is when there’s an exchanging of atoms (ionic bonding). On the contrary, cohesive forces are more on the intermolecular interactions within the adhesive or the mechanical adhesion occurring in between the molecules of the adhesive.

These explanations are best exemplified when water is poured in a glass basin. If you pour even a small amount of water into the basin, the adhesive force will be responsible in making the basin wet while the cohesive force is the ones responsible for holding the liquid together so that the total surface area of the water is minimized hence the concept of surface tension. It (cohesive force) therefore holds the individual atoms of a certain body together (in this example it is water). In practical analysis, it is without a doubt, that a diamond has greater cohesive forces within its atoms which keep its form firmly together compared to the cohesive forces between water molecules.

1. Adhesive can both be used as an adjective and as a noun while cohesive is used plainly as an adjective.

2. In Science, cohesive force is the intermolecular attraction between similar molecules or atoms while adhesive force is the intramolecular attraction between dissimilar molecules or atoms.

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