| Abstract: | The design of a continuous, stirred emulsion polymerisation reactor requires a detailed characterisation of the particle nucleation rate. Here, consideration is given to systems which use micelle-forming surfactants and water-insoluble monomers. The surfactant micelles will be considered to participate in two competing rate processes; the nucleation of polymer particles and dissolution into the aqueous phase. When the reactor operates in a steady state it is possible to obtain a size distribution function for the particles. This distribution function is used in the development of a number of diffusion equations and conservation equations. By making various sets of assumptions concerning the nucleation process, these equations are then used to obtain expressions for the particle number. By comparing the different models with experimental results it can be seen that satisfactory predictions for the particle number can be obtained without assuming that the polymer particles are always saturated with surfactant. The models also show that the radical absorption processes are not controlled by diffusion in the aqueous phase. In some cases the particle number does not reach a steady state but oscillates with time. The nature of these oscillations is described by the solution of nonlinear differential equations. Boundary conditions for these equations depend on the reaction conditions. |
