Differential Thermoanalytical Methods (DTA) are a standard tool for the characterization of chemicals and materials. Micro calorimetric Tests with DSC are widely used in material testing and for process safety studies.

For the assessment of process hazards, the knowledge of heat production rates and reaction energies is important in the first place, but the possible evolution of gas and the resulting increase in pressure is relevant as well. Many substances release gases when they are exposed to elevated temperature (peroxides, diazocompounds, azides). In some cases, these decomposition reactions are also most thermo neutral and thus can not be identified in thermoanalytical tests. If pressure and heat production rate are recorded simultaneously, the safety relevant processes can be understood and assessed much better.

Pressure Recording is important, because pressure data allow:

- the identification of the reaction type and the kinetics

- a better description of possible hazardous scenarios

- a realistic assessment of gas releases, which are not identified in the thermal signal

So far such experimental studies were carried out in quite large autoclaves which were connected to pressure sensors, e.g. by capillary tubes. No micro calorimetric methods were available.

SWISSI has developed a special capsule, which can be sealed like the well known DSC high pressure crucibles . The capsules can be used for thermoanalytical tests in the Calvetcalorimeter C80 of SETARAM. The pressure is measured with a membrane on one side of the capsule simultaneously with the recording of the heat flow (patent pending).

Advantages:

- Small sample quantity

- High thermal sensitivity and pressure recording in the same scan.

- High pressure resistivity

- No artifacts from condensation in capillary tubes

- Off-line analysis of decomposition gas is possible

Dr. Pierre Reuse

WRO-1055.5.02

CH - 4002 Basel (Switzerland)

Email: pierre.reuse@swissi.ch

Tel: +41 (0)61 696 40 90

Fax: +41 (0)61 696 70 72