Differential Thermal Analysis under High Pressure I: Investigation of the Polymerisation of Liquid Sulfur

Abstract

Abstract A DTA apparatus constructed for pressures up to 4000 bar and temperatures to 500°C is described. It was applied to the qualitative and calorimetric investigation of the monomer‐polymer equilibrium in liquid sulfur (commonly called S λ ‐S μ transition). A resulting polymerisation line determined by the connection of the floor temperatures at different pressures shows only a slight negative pressure dependence; it starts at 159°C at normal pressure and intercepts the melting curve at approx. 155°C and 1300 bar the slope of the P ( T )‐curve becoming increasingly steeper. The increase of polymer formation in liquid sulfur at the S λ ‐S μ transition can be deduced quantitatively from the calorimetric measurements.