Emulsion Polymerization of Styrene Using Reaction Calorimeter. II. Importance of Maximum in Rate of Polymerization

摘要

The importance of the maximum in the heat of reaction or rate of polymerization curve (R_(p max)) is defined by describing the main processes that occur around this maximum. The relevance of knowing when it occurs is illustrated by experiments performed in an automated reaction calorimeter. The effect of adding additional emulsifier or monomer after R_(p max) on the evolution of the number of particles and heat of reaction was studied. No new particles were formed once the maximum in the rate of polymerization was reached, whether either monomer or emulsifier was added after this maximum. Therefore, by knowing the conversion or time when the maximum in the rate or polymerization appears, it was possible to either improve the particle stability or increase the particle size and Iatex solids content, without increasing the final number of particles and without significantly affecting the reaction kinetics. This can be an important application of calorimetry. The results showed that R_(p max) defines several important factors in the emulsion polymerization process: the end of nucleation and the disappearance monomer droplets.