Silicone Antifoams
Gayatri Polychem silicon defoamers and silicon antifoams are high performance silicone based products containing non- ionic surfactants and functional additives. Foam formation is the result of dissolved molecules in a liquid. The dissolved molecules alter the surface tension of the liquid, and can be viewed as surface active agents (surfactants). The surfactants can be non-ionic, cationic, anionic, or amphoteric. The liquid can be either aqueous, non-aqueous, or both (some industrial systems may contain dissolved organics which require special consideration). Different surfactants will generate different types of silicone antifoams, antifoam emulsion, silicone antifoam emulsion and foam stability. When agitated, bubbles will form, which will immediately encounter gravitational effects pulling liquid along the bubble walls back down into the liquid beneath the bubble. A simplified picture of a bubble can be described as spherical, having both an outer wall and inner wall. When the surface tension is high enough, bubble formation becomes more rigid and stable. If a bubble is subjected to mechanical agitation, bubbles caused by entrained air, would form very stable lamellar structures. The Marangoni effect is a major stabilizing factor in foam, and is driven by osmotic pressure. In some cases, the aqueous liquid is being pulled through the bubbles' walls creating regions of low and high surfactant concentrations, which sets up a gradient along the bubbles' surface. The gradient would pump liquid back onto the bubble walls, where this phenomenon is referred to as a surface transport. The bulk viscosity also contributed to foam stability. As the viscosity of liquids increase, entrained air, now a bubble, can be trapped below the liquid’s surface. Increasing viscosity of the system also reduces the coalescence capability of smaller bubbles merging to become larger bubbles. If the bubbles become large enough (increasing the diameter), bubble stability decreases.
