THERMODYNAMICS OF 2,6-DIMETHYLPHENOL, OF THE REACTION OF ITS OXIDATIVE DEHYDROPOLYCONDENSATION, AND OF THE RESULTANT POLY(2,6-DIMETHYL-P-PHENYLENE OXIDE) AT 0-600 K

The temperature dependences of the heat capacities C-p(0) of 2,6-dimet hylphenol at 5 - 400 K and poly(2,6-dimethyl-p-phenylene oxide) at 6 - 600 K were studied with vacuum adiabatic and scanning calorimeters. T he heat of combustion of the polymer was measured with an isothermal j acketed bomb calorimeter. The results and the corresponding literature data were used to calculate (1) thermochemical parameters (Delta H-f( 0), Delta S-f(0), and Delta G(f)(0)) of formation of 2,6-dimethylpheno l and poly(2,6-dimethyl-p-phenylene oxide) at T = 298.15 K and p = 101 .325 kPa; (2) thermodynamic functions C-p(0), H-0(T) - H-0(O), S-0(T), and G(0)(T) - H-0(O) of the monomer and the polymer at 0 - 600 K, and (3) thermodynamic parameters (at 0 - 600 K and standard pressure) for the reaction of oxidative dehydropolycondensation in bulk 2,6-dimethy lphenol with the formation of poly(2,6-dimethyl-p-phenylene oxide). In the entiro temperature range of physical existence of the monomer and the polymer, the reaction of oxidative dehydropolycondensation of 2,6 -dimethylphenol thermodynamically is allowed, and the produced poly(2, 6-dimethyl-p-phenylene oxide) is thermodynamically stable with respect to depolymerization yielding the starting reactants.