On-line monitoring of emulsion polymerisation using conductivity measurements

This work investigates the feasibility of implementing conductivity measurements for the purpose of the on-line monitoring of particle generation by following the evolution of free surfactant concentration during SDS/styrene emulsion polymerisations. The conductivity and temperature were measured on-line during the reactant addition and reaction stages of a number of batch emulsion polymerisations. Samples were collected for off-line analysis of particle size and conversion. Observation of the evolution of the conductivity enabled us to measure the effect of surfactant and monomer addition. The maximum size of the monomer droplets was calculated from the decrease in conductivity that represented the adsorption of surfactant molecules onto the droplet surface. The division of SDS between the particle interface and the aqueous phase was also determined giving an indication of the particle stability.