Simulation of molecular fractionation and species distributions in phase separation of polystyrene-modified epoxy/monoamine–diamine blends

Molecular fractionation occurred at the beginning of phase separation in blends based on a polystyrene modifier and an epoxy system undergoing polymerization with a monoamine and a diamine mixed in different proportions was studied thermodynamically. The study was conducted by simulating in each separated phase the species distributions of components of the blend, the stoichiometric ratio, and the proportion of monoamine–diamine at cloud-point conditions. A model based on Flory–Huggins theory described in a previous paper Rico et al. where the interaction parameters were dependent on temperature, composition, and conversion, χ(T,image,p), and where the polydispersity of the components was taken into account, was used for simulation. The effect of modifier proportion, monoamine–diamine ratio and polymerization temperature on molecular fractionation and species distribution was determined and analyzed. Explanations of the estimated trends were given on the basis of the thermodynamic model used.