Mechanism analysis of defoamers and defoamers

Action principle of defoamer: defoamer emulsified into small droplets must enter the foam double-layer film to produce defoaming effect. Due to the lower surface tension of the active component of the defoamer compared to the system, the permeability coefficient is positive. On the surface of the bubble, defoamer droplets can penetrate the surfactant film on the stable shell layer and enter the double membrane layer of the bubble.

Since the active component of defoamer has lower surface tension than the system, so the distribution coefficient is positive, the defoamer droplet has a high distribution tendency, which makes it expand the liquid/air interface. Further distribution of defoamer will reduce the thickness of foam layer, and the change of stress will eventually lead to the rupture of foam shell, thus achieving the defoaming effect. Due to the incompatibility between the defoamer and the system, the defoamer penetrating into the foam film and spreading on the interface can push away the surfactant and the liquid in the double film layer. When the thickness of the double film is lower than the critical film thickness, the foam will burst.

The principle of action of defoamers: Defoamers replace surfactants, causing microbubbles to lose stability and rise to the surface. Defoamers promote the formation of larger bubbles. Because the rising speed of microbubbles is directly proportional to the square of the bubble radius and inversely proportional to the viscosity of the system.

The composition of defoamers and defoamers generally includes silicon-based and non silicon-based materials, usually containing well dispersed solid particles. Defoamers are generally supplied in the form of concentrated solution and lotion, and the concentrated solution is generally applicable to the grinding stage; Defoamer lotion is generally applicable to thinning stage or varnish. The concentrated solution can also be pre diluted for easy addition.