Modeling and Experimental Studies of Emulsion Copolymerization Systems. III. Acrylics ENRIQUE SALDI ´ VAR, 1 ODAIR ARAUJO, 2 REINALDO GIUDICI, 3 CARLOS GUERRERO-SA ´ NCHEZ 1 1 CID-GIRSA, Av. Sauces 87 Mza.6 Lerma Me ´xico 2 Rhodia S. A., Usina Quı ´mica de Paulı ´nia, 13140-000, SP Brasil 3 Dept. de Engenharia Quı ´mica, Universidade de Sa ˜o Paulo, 05424-970, SP, Brasil Received 27 September 2000; accepted 6 March 2001 Published online 27 February 2002 ABSTRACT: Using a previously published model and continuing the series of papers started with styrenic copolymers, predictions for evolution of conversion and average particle diameter in batch experiments are compared against experimental data for four emulsion copolymerizations involving at least one acrylic monomer: (1) methyl methacrylate/butyl acrylate, (2) methyl methacrylate/butadiene, (3) methyl methacry- late–vinyl acetate, and (4) butyl acrylate/vinyl acetate. For each system a fraction of factorial experiments were run covering simultaneous variations in five variables: initiator [I] and surfactant [E] concentrations, water to monomer ratio (W/M), monomer composition, and temperature. Data fitting is performed to represent the experimental data as several parameters are not available from independent experimental sources. The model is able to explain the effects of simultaneous changes in emulsifier concen- tration, initiator concentration, and water to monomer ratio on conversion and average particle size histories, although in some cases only qualitatively. An assessment of the degree in which a general emulsion copolymerization model is useful for practical applications is made. Physical insight is also gained by observing the trends of adjusted parameters with temperature and copolymer composition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1320 –1338, 2002; DOI 10.1002/app.10003 Key words: emulsion copolymerization; mathematical modeling INTRODUCTION The first part of this series of papers included experimental results for a number of copolymer systems produced by emulsion polymerization. In the second part, more detailed experimental re- sults and comparison with model simulations were presented for the styrenic copolymerization systems studied. In this third part the focus is on experimental data and simulations for the acrylic systems, specifically methyl methacrylate/butyl acrylate, methyl methacrylate/butadiene, methyl methacrylate/vinyl acetate, and butyl acrylate/vi- nyl acetate. This is the first work published in which an extensive set of data for several emulsion copoly- merization systems is used to assess the applica- bility of a general mathematical model in terms of its ability to fit and explain experimental data of conversion, particle size, and copolymer composi- tion. The task of modeling with some generality this type of systems is formidable, due to the complexity of emulsion copolymerization and the peculiarities of each specific pair of monomers. Correspondence to: E. Saldı ´var (esaldiva@mail.girsa. com.mx). Contract grant sponsors: CID-GIRSA, CNPq, and FAPESP. Journal of Applied Polymer Science, Vol. 84, 1320 –1338 (2002) © 2002 Wiley Periodicals, Inc. 1320