Study On The Emulsifying System Of Emulsion Polymerization Of Vinyl Acetate

In this paper, the semi-continuous emulsion polymerization of vinyl acetate stabilized by mixed surfactant of SDS/OP-10, polymeric surfactant P(AA/BA), polymerizable surfactant AMPS-Na, respectively and soap-free emulsion polymerization of vinyl acetate were carried out to gain poly vinyl acetate of emulsion of theoretical solid content of40%. The effect of type of surfactant and concentration of surfactant on the emulsion properties were studied.In the emulsion polymerization of VAc using the mixed surfactant of SDS and OP-10as stabilizer, the polymerization process went smoothly when the weight ration of SDS:OP-10in the rang of2:1～3:land the amount of the surfactant≥3%. The chemical stability and the freeze-thaw stability increased with increasing the concentration of surfactant. However, no significant difference in the dilution stability was observed. The vicosity of colloidal increased and the film of PVAc get more poor water resistance.The polymerization of VAc went smoothly in the prensence of1%～3%polymeric surfactant P(AA/BA). PVAc emulsion showed good dilution stability and chemical stability.The freeze-thaw stability increased with increasing the level of surfactant. Latex particle size distribution became narroe with increasing the concentration of surfactant.When the PVAc used as the wood adhesive, the compression shear strength first decreased and then increased with increasing the amount of surfactant.We also investigated the surfactant-free emulsion copolymerization of VAc and acrylic acid. Experimental results showed that the chemical stability, dilution stability and freeze-thraw stability increased with increasing the level of AA.On the other hand, the emulsion viscosity, water adsorbpting and Tg of the PVAc film increased with increasing the amount of AA. In the copolymerization of VAc, AA and BA, with the increasing of BA, the polymerization stability, dilution stability and chemical stability get improved.In the polymerization of VAc stabilized by AMPS-Na, the pre-emulsified of VAc and AMPS-Na could help the polymerization process go smoothly before inducing the polymerization. Experimental results showed that the amount of AMPS-Na have a little effects on the dilution stability of PVAc emulsion,the chemical stability and freeze-thraw stability increased with increasing the level of AMPS-Na.