Emulsions
Emulsions are systems of two immiscible liquids in which droplets of one liquid are dispersed into another. These liquids are physically distinct phases, consisting of a dispersed phase and continuous phase. The Microfluidizer processor has unparalled results achieving stable emulsions with droplet sizes attainable in the submicron to nanometer range depending on the desired outcome.
Processing pressure and number of passes must be determined for each system. There is a point at which a higher energy input, whether in the form of additional passes or higher pressure, causes an increase, not a decrease, in droplet size. Running a sample in Microfluidics’ in-house laboratory can help determine the perfect combination for your product.
Temperature control is important. Most emulsions should be kept cool. That is the purpose of the cooling coil or heat exchanger. The typical temperature rise of a fluid processed through a Microfluidizer processor is 1.7 degrees centigrade per 1,000 psi per pass. For example, if you run a formulated system for 1 pass at 20,000 psi, the product stream temperature will rise 34 degrees Centigrade.
Cooling may not be desirable when processing a high viscosity liquid. In most cases it is easier to emulsify a liquid with a lower viscosity because the droplets require less energy to achieve separation. Dispersing high viscosity liquid into water, for example, may call for a higher temperature to reduce the viscosity. Many formulations are composed of a resin or wax emulsion in which the dispersed phase was solid or highly viscous at room temperature. The emulsion, prior to being introduced to the Microfluidizer equipment, can be heated to a temperature at which the dispersed phased is a liquid of lower viscosity than at room temperature. This system can be processed for two or three passes without cooling. Then a final pass can be performed with cooling which increases the stability of the product.
Below are before and after microscopic shots of an emulsion that the customer wanted to stay stable for a minimum of 5 days. Their previous mixing method resulted in separation in less than 24 hours. With just one pass through an M-110Y Microfluidizer processor at 18,000 psi, the end product was stable for a minimum of 5 days at either refrigerated or ambient temperatures. Learn more about emulsions in the Pharmaceutical, Chemical, Personal Care, and Food industries.
Before
After (1 pass @ 18,000 psi)
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