SEMIBATCH EMULSION POLYMERIZATION OF BUTYL ACRYLATE - EFFECT OF FUNCTIONAL MONOMERS

The concentration of sodium lauryl sulfate (SLS) in the initial reacto r charge is the most important parameter in determining the latex part icle size during semibatch emulsion polymerization of butyl acrylate i n the presence of acrylic acid (AA), methacrylic acid, or hydroxyethyl methacrylate. The final latex particle size decreases with increasing concentration of SLS, NP-40, or functional monomer. The carboxylic mo nomer AA is the most efficient functional monomer to nucleate and then stabilize the latex particles. The plot of log N-f vs log SLS shows a slope of 0.4-0.8, which is more consistent with Feeney's analysis bas ed on the coagulative nucleation mechanism. Experimental data also sho w that the particle size first decreases to a minimum and then increas es with an increase in the concentration of the neutralizing agent NaH CO3. The optimal concentration NaHCO3 for achieving the smallest latex particle size occurs at a point close to 0.15-0.29%. Experimental dat a of the particle size distribution and molecular weight distribution show that the aqueous phase reaction can play a very important role du ring the particle nucleation period.