THERMODYNAMICS AND STRUCTURE OF POLYDIMET HYLSILOXANE-METHYLETHYLKETONE SYSTEM

The phase equilibria and structure of polydimethylsiloxane-methylethyl ketone system were studied by light scattering, viscometry, and thermo chemistry, The binodal and spinodal, partial enthalpies and entropies of mixing were determined. The phase diagram is distinguished by an up per critical solution temperature. The dissolution of PDMS in MEK is e ntropic in nature. The dimensions of macromolecules and supermolecular associates were determined. It was shown that macromolecular associat es form close to the binodal. In solutions with the concentration lowe r than the critical, the dimensions of the associates decrease when th e temperature decreases and remain unchanged in more concentrated solu tions. The associates have the smallest dimensions in solutions of cri tical composition.