Summary: The thermodynamic properties – the temperature dependence of heat capacity and the temperatures and enthalpies of physical transitions – of poly(pentamethylene urethane) and poly(hexamethylene urethane) have been studied over the range 6 to 450 K by precision adiabatic vacuum and dynamic calorimetry. Their energies of combustion, ΔcU, have been measured in a calorimeter with a static bomb and an isothermal shield. The calorimetric data were used to determine the temperature dependences of the heat capacity = f(T) for poly(pentamethylene urethane) and poly(hexamethylene urethane) in crystalline and amorphous states, to calculate the thermodynamic parameters of the glass transition and the glassy state, the thermodynamic quantities of fusion and the thermodynamic functions (T), H0(T) ? H0(0), S0(T) ? S0(0) and G0(T) ? H0(0) of the polymers for the temperature range from 0 to 450 K. The enthalpy of combustion ΔcH0 and the standard thermodynamic characteristics of formation, namely, the enthalpy, ΔfH0, entropy, ΔfS0 and Gibbs function, ΔfG0, of the substances under discussion were estimated at T = 298.15 K. The regions of thermal resistance for the tested compounds were determined calorimetrically.
Temperature dependence of of poly(pentamethylene urethane)(A) and poly(hexamethylene urethane)(A′).
