THERMODYNAMICS OF DEPOLYMERIZATION OF BIOTECHNOLOGICAL POLY[(R)-3-HYDROXYBUTYRATE] WITH FORMATION OF -4,8,12-TRIMETHYL-1,5,9-TRIOXADODECA-2,6,10-TRIONE AND OF ITS POLYMERIZATION WITH RING-OPENING TO HIGHLY ISOTACTIC POLY[(R)-3-HYDROXYBUTYRATE] FROM 0 TO 500 K AT STANDARD PRESSURE

In adiabatic vacuum and dynamic calorimeters the temperature dependenc e of the heat capacity C-p(0) of -4,8,12-trimethyl-1,5,9-trioxadodeca- 2,6,10-trione (a twelve-membered cyclic trilactone), biotechnological poly[(R)-3-hydroxybutyrate] and highly isotactic poly[(R)-3-hydroxybut yrate] was studied between 5 K and 500 K; temperatures and enthalpies of melting of the above mentioned substances were measured. In a calor imeter with a static bomb and an isothermal shield the energy of combu stion of the same substances was measured. From the results the thermo dynamic functions C-p(0)(T), H-0(T) - H-0(0), S-0(T), G(0)(T) - H-0(0) were calculated in the range of 0 K to 500 K and thermochemical param eters Delta H-comb(0), Delta H-f(0), Delta S-f(0), Delta G(f)(0) were estimated at T = 298,15 K and standard pressure. The thermodynamic par ameters of depolymerization of the biotechnological polymer to the 12- membered trilactone Delta H-depoI(0), Delta S-depol(0), Delta G(depol) (0) and of the polymerization of the monomer formed in the highly isot actic poly[(R)-3-hydroxybutyrate] Delta H-pol(0), Delta S-pol(0), Delt a G(pol)(0) were calculated for 0 K to 500 K.