Thermodynamics of depolymerization of biotechnological poly[(R)-3-hydroxybutyrate] with formation of (R,R,R)-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 dependence of the heat capacity C-p(0) of (R,R,R-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-hydroxybutyrate] was studied between 5 K and 500 K; temperatures and enthalpies of melting of the above mentioned substances were measured. In a calorimeter with a static bomb and an isothermal shield the energy of combustion of the same substances was measured. From the results the thermodynamic 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 parameters 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 parameters 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 isotactic poly[(R)-3-hydroxybutyrate] Delta H-pol(0), Delta S-pol(0), Delta G(pol)(0) were calculated for 0 K to 500 K.