VAc/BA核壳乳液聚合乳胶粒形态演化

由两种单体分阶段种子乳液聚合制得的核壳型乳胶粒 ,可能存在着多种多样的形态 .由于不同的形态在使用中具有不同的性能 ,因此 ,核壳型乳胶粒的结构形态的研究一直受到人们的十分重视 .近年来 ,Ｓｕｎｄｂｅｒｇ[1] 等指出 ,正向、反向、两半球、两种孤立粒子等四种形态是热力学平衡形态 ,其他形态则是未达平衡的过渡形态 .并且提出用界面自由能最小的方法判别其中哪一种是最终平衡形态 .显然 ,自不平衡形态到平衡形态需要链迁移 ,Ｃｈｅｎ[2 ] 、Ｊｏｎｓｓｅｎ[3 ] 、Ｇｏｎｚａｌｅｚ[4] 等指出 ,链迁移的阻力是粘性力 .对于聚醋酸乙烯酯…

MORPHOLOGICAL EVOLUTION OF LATEX PARTICLES FOR VAc/BA CORE/SHELL PREPARED BY TWO STAGE EMULSION POLYMERIZATION

The morphological evolution of the latex particles obtained by VAc/BA two stage emulsion polymerization was studied. The designs of two group experiments were as follows:VAc as seed , BA was added in starved or overflown condition. The inverted core shell composite latex particles, with PVAc as shell and PBA as core, were found in overflown condition, however, the core shell composite latex particles, with PVAc as core and PBA as shell were found in starved condition. When the core shell composite latex particles in different time in starved condition was kept to reaction end, the morphology of the latex particles inverted. Comparing with the previous work in literature, this paper can provide better and more complete understanding about the morphological evolution of the latex particles in the process of seeded emulsion polymerization of VAc/BA. The photos of TEM of morphology of the latex particles in the process under two conditions and temperature being kept constant were obtained. From viscosity,the existed paradoxical views about the morphology of the latex particles on VAc/BA can be explained in a better and more complete way.