The terms anti-foam (or antifoam) agent and defoamer are often used interchangeably, but they in fact differ. Defoamers eliminate existing foam, while anti-foamers prevent the formation of more foam. Antifoams are typically added to the foaming solution before foam formation and act to avoid excessive foam formation. In contrast, defoamers or foam breakers are substances sprinkled over existing foam, aiming to induce rapid foam collapse. In industrial processes, foams may create serious problems. They can cause defects on surface coatings and stop the efficient filling of containers. Many different chemical formulae are available to avoid the formation of foams. This article will look at how anti-foam and defoaming agents work, the different types of defoamers, and their applications.
How Defoamers and Antifoaming Agents Work
Foam the coarse dispersion of gas in liquid, where the volume fraction of gas is more significant than that of the liquid. The bubbles will migrate to the surface because their density is less than that of the liquid. As the bubbles coalesce and collect at the surface interface, the bubble walls thin and break. Defoamers work by accelerating the process and breaking the smaller bubbles too. Usually, a defoamer is insoluble in the foaming medium and has surface-active properties.
A vital feature of defoamers is the ability to spread rapidly on foamy surfaces. Another feature is partial solubility. A defoamer must not be too dispersible or too soluble. If it goes too far in either direction, it will not break up foam and may even contribute to additional foam build-up.
Furthermore, defoamers must have low surface tension so that they can spread rapidly along the surface interface to achieve maximum interaction with the foam. As an effective defoamer disperses, it must be capable of displacing the foam-stabilizing surface-active components and penetrating the foam's lamellae to allow the entrapped gas to escape and the foam to burst.
How do antifoaming agents work? They also function by entering the interface between the air and foam's lamellae. The antifoam penetrates the bubble wall, which is bridged by the antifoam droplet. This is called "bridging of the film." As the antifoam spreads, the bubble wall is thinned. Once the antifoam has entered the lamella, it forms a lens on the lamella and begins to spread. The progressive spreading process reduces the lens's thickness, which is altered by movements in the foam. Stresses occur until the lens breaks and the foam lamella ruptures. The resultant film is considerably less elastic than the surfactant film, which previously stabilized the lamella. This destabilization facilitates the rupture of the lamella.
ABOUT CEMOTECH
→ Suzhou Cemo New Material Technology Co.,Ltd is a high-tech enterprise specialized in construction additives.
→ Estabilished in 2011 and expanded production scale in 2015.
→ Our production capacity is 10,000 tons of redispersible polymer powder, 5000 tons of polycarboxylic acid superplasticizer, 3000 tons of melamine superplasticizer, 2000 tons of defoamer, gypsum retarder, hydrophobic agent and other additives.