Isothermal Calorimetric Method Research Articles

The calorimetric study in the 13·8–340°K range of δ-valerolactone, its polymer, and of the δ-valerolactone polymerization

Precision adiabatic and isothermal calorimetric methods have been used for the first time to study the thermodynamic properties of δ-valerolactone (VL), its polymer (PVL) and the thermodynamic parameters of the VL bulk polymerization. The heat contents C° p of the monomer and polymer were determined with ∼0·3% precision, also the temperature and enthalpy of the physical transitions; the functions H° ( T)− H° (0), S° ( T) and G° ( T)− H° ()) have been calculated for the 0–350°K range. The S° g (0), S° er, H° g (0)− H° er (0) values of the PVL have been estimated in the glass-like state. The enthalpy of the VL→PVL process has been determined at 298·15°K and p = 101·325 kPa. The found values have been used to calculate the enthalpy, entropy and Gibbs energy of the VL polymerization and also the equilibrium concentration of the monomer in the reaction mass at normal pressure.

Twin isothermal calorimeter method for the determination of specific heat of soil

Abstract The twin isothermal calorimeter method was proposed for determining the specific heat of soil. A high accuracy of measurement (±3%) was gained in comparison with other methods. The twin isothermal calorimeter consisted of two Dewar flasks of the same size in a constant-temperature bath. Each flask was equipped with a thermometer, a heater, and a stirrer. The most advantageous point in this method is to measure directly the temperature changes of the samples by means of the twin structure of the calorimeter. The specific heat of quartz sand and a few kinds of clay was measured. The results were sufficiently good.