EMULSION COPOLYMERIZATION OF STYRENE AND N-BUTYL ACRYLATE IN PRESENCEOF ACRYLIC AND METHACRYLIC ACIDS - EFFECT OF PH ON KINETICS AND CARBOXYL GROUP DISTRIBUTION

The batch emulsion copolymerization of styrene with n-butyl acrylate i n the presence of acrylic and methacrylic acids was investigated. Valu es of reaction rate and conversion observed at different pH values wer e examined. The effect of pH on the glass transition temperature of th e polymers was also investigated and the results compared with model p redictions. Its effect on the distribution of the carboxyl groups at d ifferent positions within the emulsion system (surface and core of par ticles, and in the aqueous phase) was also analyzed. Three methods wer e used to measure the number of carboxyl groups: conductimetry, organi c phase potentiometry, and titration with a solution of sodium hydroxi de in methanol. (C) 1997 John Wiley & Sons, Inc.