Emulsification Of Rosin Solution With Magnesium Aluminum Hydroxides Based Emulsifiers

The emulsifying effects of positively charged colloidal magnesium aluminum hydroxides on rosin solution/water system as a microparticle emulsifier either alone or together with modified montmorillonite, cationic polyacrylamide and ethyl cellulose separately were investigated. The morphology of the rosin emulsion, the structure and water resistance of air-dried rosin emulsion, and the conglomeration of the emulsifier on the interface of emulsion were analyzed by scanning electron microscope, contact angle meter, energy spectrum and X-ray photoelectron spectroscopy.Rosin solution/water can be emulsified to form uniform water in oil emulsion by magnesium aluminum hydroxides. The emulsion viscosity reaches its maximum and phase inversion occurs when the oil-water ratio is less than 1:2. The emulsions stabilized by magnesium aluminum hydroxides are delaminated into two phases: coarse emulsion and emulsion. The amount of coarse emulsion increases with the increase of oil phase. The emulsion delaminated into coarse emulsion and water phase when modified montmorillonite was used as an emulsifier alone. The phase version point of the coarse emulsion is situated at a 1:1 oil-water ratio approximately. However, the modified montmorillonite can improve the emulsifying and stabilizing effect of the magnesium aluminum hydroxides and have no effect on the emulsion type. Although magnesium aluminum hydroxides can also improve the emulsifying and stabilizing effect of modified montmorillonite on rosin solution, uniform emulsion will form when considerably large amount of magnesium aluminum hydroxides are introduced.Cationic polyacrylamide with high molecular weight and low charge density can promote the formation of oil in water emulsion when used alone. However, it can neither improve the emulsifying and stabilizing effect of magnesium aluminum hydroxides on rosin solution/water nor and change its emulsion type. In contrast, it promotes the appearance of water phase when its dosage is low. With the increase of cationic polyacrylamide addition level, the emulsion stability is improved, its droplet is enlarged and the amount of coarse emulsion is reduced. Yet, a little amount of magnesium aluminum hydroxides is favorable to improve the system stabilization if it was used together with cationic polyacrylamide.Ethyl cellulose can emulsify rosin solution/water into water in oil emulsion, but coarse emulsion is easy to be separated out. When used with magnesium aluminum hydroxides it can improve the emulsion stabilization drastically and form stable water in oil emulsion. During the emulsifying process, higher shear force leads to lower emulsion viscosity and more stable emulsion. The suitable increase of temperature helps to lower the emulsion viscosity. The emulsion will be destabilized by salts and delaminated to water phase and coarse emulsion. Magnesium aluminum hydroxides and ethyl cellulose may congregate on the interface. The former helps to improve the emulsification of rosin solution by decreasing the emulsion drop size. The latter helps to improve the stability of rosin emulsion by increasing the emulsion viscosity.Rosin film with micropores formed after the water drops in rosin emulsion vaporized when the water in oil rosin emulsion was air-dried. The rosin film with more micropores shows better hydrophobicity. The emulsion changed from water in oil type into oil in water type after it was diluted by ethanol. Rosin microspheres formed after the ethanol diluted emulsion was air-dried, which lowed the hydrophobicity of rosin film.