A critical evaluation of reaction calorimetry for the study of emulsion polymerization systems: thermodynamic and kinetic aspects

Protocols were examined for the measurement of rates and enthalpies of polymerization (ΔHp) using reaction calorimetry. ΔHp was determined to be 70.2 kJ mol−1 for a series of seeded styrene emulsion polymerizations under typical emulsion conditions, in good agreement with literature values. However, there was a significant deviation from this value for small-particle systems, which is ascribed to surface effects, i.e. environmental effects on ΔHp. Careful comparison between rate data obtained by calorimetry and by dilatometry leads to recommended procedures for obtaining reliable and accurate rate data using the former technique.