不完全相反转乳化过程分散相水滴形态发展研究

相反转乳化技术是制备高分子树脂水基分散体系的新方法1～4].相反转指多组分体系(如油/水/乳化剂)中的连续相在一定条件下相互转化的过程,如在油/水/乳化剂体系中,其连续相由水相向油相(或从油相变为水相)的转变.在连续相转变区,体系的界面张力最低,因而分散相的尺寸最小.同理,可利用相反转技术直接将高分子树脂乳化为尺寸很小的水基微粒,即制备高分子树脂的水基分散体系.由于高分子树脂的粘弹性及相反转过程的复杂性,对高分子树脂的相反转乳化过程的机理研究较少.杨振忠5]等通过调节高分子非离子型乳化剂浓度,可以有效地控制相反转完善程…

THE MOPHOLOGICAL EVOLUTION OF WATER DROPLETS DURING INCOMPLETE PHASE INVERSION PROCESS

Phase inversion emulsification technique is an effective physical method to prepare waterborne dispersions of polymeric resins. In this study, a multi\|hollow epoxy resin sphere was obtained by incomplete phase inversion emulsification. The dynamic morphological evolution of water droplets dispersed in bisphenol. A epoxy resin/emulsifier (a multi\|block copolymer) during phase inversion process was investigated with scanning electron microscopy. It is shown that small discrete water droplets are dispersed in the epoxy resin continuous phase at low water content. In this case, the dynamic coalescence among the small water droplets is ignored. With increasing water content, the dynamic coalescence becomes remarkable and larger water drops are formed by the coalescence among the small water droplets. The larger water drops are randomly distributed within the continuous phase. Meanwhile, some necklace like structures with varied length co\|exist with the small water droplets and larger water drops. Incomplete phase inversion is achieved through the coalescence among the larger water drops, and some small water droplets are entrapped therein. In this case, a kind of multi\|hollow sphere is obtained. While, in some local regions, all the nearest small water droplets coalesce simultaneously to be continuous phase to achieve complete phase inversion, and small discrete waterborne particles are obtained. The dynamic coalescence among the small water droplets dispersed in epoxy resin continuous phase could be analyzed in terms of the improved Smoluchowski equation.