Microencapsulation of imidazole curing agents by spray-drying method using W/O emulsion

Abstract

Imidazoles were microencapsulated for the latent curing of the epoxy resin imidazole system. Using polycaprolactone as the wall material, the microcapsules were formed by spray-drying method using water/oil (W/O) emulsion. Poly(vinyl alcohol) was used as the emulsion stabilizer. The imidazoles used in this study were imidazole and 2-methylimidazole. The amount of imidazoles in the microcapsule was measured using elemental analysis. The permeability of the microcapsules was measured in ethanol, and the shelf life of the microcapsules was also studied for the epoxy resin. The curing behavior of these microcapsules to epoxy resin was examined using a differential scanning calorimeter. In the curing reaction, the microcapsule of imidazoles exhibited delayed kinetic behaviors compared to pure imidazoles. And the curing times were estimated at 150 and 180 degrees C using an indentation method. These microcapsules of imidazoles exhibited a long shelf life. When comparing the previous method in which simple dichloromethane solution was used for spray-drying, finer microcapsules were formed using the W/O emulsion. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012