Thermodynamics of 2,2‐dimethyltrimethylene carbonate, of its bulk polymerization process and of poly(2,2‐dimethyltrimethylene carbonate) from 0 to 470 K at standard pressure

Abstract

In the present work the thermodynamic properties of 2,2-dimethyltrimethylene carbonate (DTC) and poly-2,2-dimethyltrimethylene carbonate (PIYE) were studied by precise calorimetry. In adiabatic and dynamic vacuum calorimeters the temperature dependence of the heat capacity of DTC and PDTC was studied between 5 and 470 K. Temperature and enthalpies of physical transitions were determined, and in an isothermal calorimeter energies of combustion of the above compounds were measured. From the results the thermodynamic functions C,"( T), W ( T ) -Ho (0), So (T), Go ( T ) -Ho (0) were calculated for various physical states of the monomer and the polymer from 0 to 470 K. The standard enthalpies of combustion and thermochemical parameters of formation AH,", AS;, AG," of the objects studied were estimated at T = 298,15 K andp = 101,325 kPa. The zero entropy Sil(0) and configurational entropy SEonf of PDTC in the glassy state and the difference in zero enthalpies of the polymer in the glassy and crystalline states Hs(0)-HEr(O) were estimated. The results were used to calculate the thermodynamic parameters of the bulk polymerization of DTC (AH;ol, Miol, AG&) in the range of 0 to 420 K. It was established that for the process DTC + PDTC, AGhl < 0 if the polymer is crystalline and AG;,, > 0 in the case of amorphous PDTC (glassy or liquid). The ceiling temperature is = 500 K.