Calorimetry

High-pressure calorimetry is a technique to measure the heat flux of pressurized substances. A special kind of differential scanning calorimetry (DSC) is the transitiometer, which enables a pressure range up to 4000 bar and a temperature range up to 300°C.

In contrast to common DSCs, the transitiometer facilitates simultaneous recording of pressure and volume as well as sensitive measurements of heat flux. Hence pressure, volume and temperature are measured beside the calorimetric signal. Therefore, a common measuring setup is the following: One physical property is kept constant, the second one is selectively varied and the effect on the third one is monitored. In this way various physical properties like density, expansion coefficient, compression modulus or heat capacity are accessible.

With this method, liquids and polymers are researched in using Standard Unit transitiometer and gases are investigated using the Advanced Unit transitiometer. Moreover, the kinetic of peroxide decompositions can also be examined by the Standard Unit, because of the strongly exothermal nature of the reaction causing an intense calorimetrical signal. The kinetic of peroxide decompositions are of interest applying it as initiators for high-pressure LDPE-polymerisation.

The experimental measurements of these physical properties are beneficial because literature data under high-pressure conditions are rarely available but vital as the basis for simulations.