Calorimetric study of tetramethylene urethane and of poly(tetramethylene urethane) between 0 and 300 K

Abstract

In an adiabatic vacuum calorimeter the temperature dependence of the heat capacity C p 0 of tetramethylene urethane (TMU) (2-oxo-hexahydro-1,3-oxazepine) and poly(tetramethylene urethane) (PTMU) was studied between 4.3 and 300 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield the energies of combustion D U comb of the monomer and the polymer were measured. From the experimental data the thermodynamic functions C p 0 , H 0 (T)-H 0 (0), S 0 (T), G 0 (T)-H 0 (0) were calculated in the range of 0 to 300 K, and enthalpies of combustion D H 0 comb and thermochemical parameters of formation D H 0 f , D S 0 f , D G 0 f of TMU and PTMU were estimated at T = 298.15 K and standard pressure. The results obtained were used to calculate the thermodynamic characteristics of TMU polymerization in bulk (DH 0 pol , D S 0 pol , > PTMU is far on the side of the polymer. The upper (ceiling) limiting temperature of TMU polymerization is T 0 ceil A 1 000 K.