Stability and film properties of tung oil modified soybean alkyd emulsion

A series of tung oil modified soybean alkyd emulsions are prepared by an inversion emulsified technique. In these alkyd resins, the tung oil contents are about 0, 12.5, and 25.0 wt % (based on the total oil). Using IGEPAL, CO-630 as the surfactant, a very stable alkyd emulsion can be obtained. With the increase of the tung oil contents in alkyd emulsions, the initial droplet sizes of the emulsions increase dramatically. Aging under 50 degrees C can eliminate the difference in droplet sizes; the final droplet sizes of the emulsions are about 50 nm. The alkyd resins also have good hydrolytic stability. The tung oil contents in the alkyd resins also strongly influences the film properties; suitable tung oil content improves the film gloss. An atomic force microscopy investigation shows that the film from the alkyd emulsion is more water sensitive; after a 50-h deionized water immersion, the film surface appears to have a lot of dents. This indicates that the film surface may be very rich in surfactant species. (C) 2000 John Wiley & Sons, Inc.