Abstract: The morphological evolution with phase inversion process in emulsifying bisphenol Aepoxy resin was observed by SEM. It is revealed that the phase inversion process is completely achieved at the phase inversion point(PIP) when the concentration of the emulsifier is high, and a kind of sub micro waterborne particles of narrow size distribution is prepared. When the concentration of the emulsifier is low, the phase inversion process is incompletely achieved at PIP, and a kind of porous complex big waterborne particles of wide size distribution is obtained. In the former case, the interfacial layer of W/O structure is strong enough to impede the coalescence among water droplets before PIP. When the content of water reaches a critical value, the attraction between water droplets exceeds the repulsion, the nearest water droplets coalesce simultaneously to be continuous phase, which causes the complete phase inversion. In the latter case, the coalescence among the water droplets is noticeable due to the weak interfacial layer of W/O structure. Thus, the water droplets become larger after the coalescence and randomly dispersed in the continuous phase. The larger water drops coalesce furtherly to be continuous phase promoted by strong shear field and the W/O/W structure is formed. This is the feature of incomplete phase inversion.

Key words: Bisphenol A epoxy resin, Phase inversion, SEM, Morphological evolution, Waterborne polymer particles