High solids content miniemulsion polymerization of vinyl acetate in a continuous stirred tank reactor

The dynamics of high solids content miniemulsion polymerization of vinyl ac etate produced in a continuous stirred tank reactor (CSTR), under different emulsification processes and hydrophobes were studied. In order to gain mo re insight into the process, a previous kinetic study in a batch reactor wa s performed. In addition, the rheological behavior of latexes produced by m iniemulsion was compared with those obtained by conventional emulsion. From the experiments made in batch mode, it was observed that poly(vinyl acetat e) or polystyrene as the sole hydrophobes were able to create miniemulsions as far as the time elapsed between sonication and polymerization was small . The same behavior was observed in the CSTR, where the feasibility of thos e systems to eliminate the oscillatory performance of CSTR reactors, also a t high solids content was demonstrated. The sonication itself or the sole p resence of hydrophobe - without sonication - was not enough to avoid the os cillatory behavior. Further, it was shown that the viscosity of miniemulsio ns at the beginning of the CSTR process is notably lower than emulsions, th us preventing the initial mixing and heating problems. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.