Modelling the influence of nanoparticles in the phase behaviour of an epoxy/polystyrene mixture

The cloud point temperatures of four series of epoxy/polystyrene blends have been experimentally determined as a function of polymer mass and system composition. The phase diagrams show an UCST behaviour, increasing incompatibility as the molar mass increases. The Flory–Huggins theory with a concentration-dependent interaction parameter has been developed to study the compatibility of two polymers in presence of spherical nanoparticles. This theory has been first compared with the experimental cloud point curve in absence of nanoparticles, and secondly it has been used to predict the thermodynamic behaviour in presence of different volume fraction of nanoparticles. Nanoparticles coated with two types of functional groups have been tested. It can be concluded that the inclusion of nanoparticles increases compatibility. Moreover concentration-dependent interaction parameters have been obtained in these systems for the first time.