Relationships between lnitiator Amount and Properties of Polymer Emulsion Obtained by Polymerization of Vinyl Acetate in the Presence of Poly(vinyl alcohol) as Emulsifier

Abstract

The experiment dealing with the emulsion polymerization of vinyl acetate has been carried out in the presence of poly(vinyl alcohol) as emulsifier using hydrogen peroxide as initiator, and the effect of the initiator amount on the properties of polymer emulsion has been investigated. The monomer was dropped by means of a continuous addition, process, and the initiater was added just before the start of monomer dropping and then at intervals of 30 min during a period of polymerization. With increasing initiator amotmt, an apparent viscosity of polymer emulsion inereased, reached a maximum, and then decreased. The effect on the viscosity of the initiator amount added just before the start of monomer dropping was significantly higher than that of initiator amount added during a peripd of polymerization. From the variation in the particles of polymer emulsions obtained by the polymerizations and the properties of the polymer firms, it seems that these results are caused by the interaction between poly(vinyl alcohol) and, the hydroxyl and groups of the polymer molecules coming from initiators or poly(vinyl alcohol)parts in graft polymers, which exist on the surface of the poly(vinyl acetate) particles.