THERMODYNAMICS OF MIXING IN OLIGOBUTADIEN EURETHANE(METH)ACRYLATE-OLIGOESTERACRYLATE SYSTEMS

The thermodynamics of formation of supermolecular and phase structures in butadieneurethane(meth)acrylate-oligoesteraclylate mixtures has be en studied. The phase equilibrium in this oligomeric system was analyz ed within the framework of a modified Flory theory. The temperature an d concentration dependences of the thermodynamic functions of mixing i n semidulute (left binodal branch) and dilute (right binodal branch) s olutions were determined. There are three temperature regions function ally related to the upper critical solution temperature (UCST), which exhibit different patterns of variation of the thermodynamic parameter s. The invariance of the thermodynamic functions of mixing with respec t to UCST is interpreted in terms of binodal invariance in the systems studied.