Study On The Core-Shell Morphology Kinetics Of Emulsion Polymerization Of Vinyl Acetate And Butyl Acrylate

Latex system with well-designed particle morphology are necessary for advancedengineering plastics with high impact strength and improved toughening, for optimumpeel strength of adhesives, and many other highvalue-added productes in otherapplication areas such as membrane separation and biotechnology. Elucidation of themorphology of composite latex particles and their control was the goal of manypublished papers. Sundberg (1986) proposed that the criterion of the ultimate paritclemorphology is the principle of minimum surface free energy change, This theory hasbeen admitted widely in the past decades. Gonzalez (1995) advanced a mathematicalmodel of cluster migration dynamics to simulate the development of particlemorphology in emulsion polymerization, and then the cluster dynamics theory was usedto reacting systems of polystyrene/poly(methyl-methacrylate) in 1996. Thisachievement brought about Delacal's work a step forward. Delacal proposed that theultimate particle morphology is decided by the distribution of free radicals andsimulated the morphology of VAc-BA batch copolymerization. Cluster dynamics is amilestone in the development of Core-Shell morphology kinetics. In this paper thesystem of VAc-BA was choosed as the research object, the arm is to provide a furtherexample for cluster dynamics, and to extend it from two stage seed polymerization tocopolymerization system morphology research. Owing to the fact that the VAc-BAsystem is just the same as Delacal's simulation system while the research starting pointis diffferent, so we can make use of it for investigation .In order to achieve the goal, the design of experiment is as follows: Vac and BA as seed separately, chain transter agent is added or not, two stage small seed polymerization with four group experments. The latex was determined by TEM and DSC. the results showed that , the four group experments got the same core-shell composite latex particles with BA as the core and VAc as the shell. Kinetics data were obtained and a simplified kinetics model was established, by which the development of particle morphology of the four group experiments were simulated by using the method of cluster dynamics. Small seed forms core -shell structure easer than the large seed,...