THERMODYNAMICS OF N-DIOXANONE, POLYMERIZA TION REACTION, AND POLY-N-DIOXANONE AT 0-450 K

Temperature dependences of heat capacities of n-dioxanone and poly n-d ioxanone in the temperature interval 5 - 450 K were investigated with the help of adiabatic and dynamic calorimetry. The temperatures and en thalpies of transitions between different physical states were determi ned. Temperature regions corresponding to various physical states of t he monomer and the polymer were found; Combustion energies were measur ed with the help of isothermal calorimeter equipped with a calorimetri c bomb. The results of termine a number of thermodynamic characteristi c of the compounds under investigation. These include parameters of me lting; parameters of glass transition and those of the glass state of the polymer formed; thermodynamic functions over the temperature inter val from 0 to 450 K; standard combustion enthalpies and thermodynamic parameters of formation for both compounds. The experimental data, com bined with the results of theoretical analysis, were used to find othe r thermodynamic parameters of the process of bulk polymerization of n- dioxanone into poly-n-dioxanone at 0 - 450 K: enthalpies, entropies, a nd Gibbs' functions. The effect of physical states of the reagents and polymerization temperature on the thermodynamic properties of the mon omer and polymer and on the parameters of polymerization reaction at s tandard pressure were analyzed. Thermodynamic parameters characterizin g polymerization-depolymerization equilibrium and equilibrium concentr ations of the monomer in monomer reversible arrow polymer reaction mix ture were determined for several different temperatures. It was establ ished that the upper limiting temperature for the polymerization of n- dioxanone is higher than the temperature at which thermal destruction of the reagents begins.