EPOXY-AMINE SYSTEMS WITH MONODISPERSE MODIFIERS - THERMODYNAMIC ANALYSIS OF THE PHASE-SEPARATION PROCESS TAKING THE POLYMER POLYDISPERSITY INTO ACCOUNT

Phase separation during polymerisation was studied by taking into acco unt in the thermodynamic analysis the generated distribution of polyme r species. A model system consisting of a diepoxide based on diglycidy lether of bisphenol A, a diamine and castor oil as modifier was consid ered. One- and two-step polymerisation processes were simulated (in th e two-step process a first step was carried out with an epoxy excess u p to a particular conversion, stoichiometry was balanced and the react ion continued in a second step). A thermodynamic analysis for a monodi sperse modifier-epoxy/amine system was performed taking the polydisper sity of the polymer into account. It was shown that the cloud point co nversion was decreased when the polymerisation was carried out in two steps. This effect was enhanced for lower stoichiometric ratios (highe r epoxy excesses) and higher epoxy conversions in the first step. The dispersed phase became richer in low molecular weight species than the continuous one. In particular both monomers increased their concentra tion in the dispersed phase.