Angle of wetting is zero, it reflects that attraction between the molecules is:
Correct Answer: Molecules of adhesive are attracted to molecules of adherend as much as or more than they are attracted to themselves
Description: If the force of attraction between molecules of the adhesive and molecules of the substrate is stronger than the attraction between molecules of the adhesive, the liquid adhesive will spread much more broadly over the solid surface and result in a smaller contact angle. Thus, a small contact angle indicates that the adhesive forces at the interface are stronger than the cohesive forces holding the molecules of the adhesive together. If the adhesive beads up, it means that the force of adhesion is weaker than the cohesive force of the adhesive. Because the tendency for the liquid to spread increases as the contact angle decreases, the contact angle is a useful indicator of spreadability or wettability. Complete wetting occurs at a contact angle of 0° and no wetting occurs at an angle of 180°
Thus, the smaller the contact angles between an adhesive and an adherend, the better the ability of the adhesive to flow into and fill in irregularities within the surface of the adherend. The fluidity of the adhesive influences the extent to which these voids or irregularities are filled.
Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 26
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