Simultaneous X-Ray Diffraction and Differential Scanning Calorimetry (XDDSC) in Studies of Molecular and Liquid Crystals

Abstract

The technique of simultaneous X-ray diffraction and differential scanning calorimetry (XDDSC) is introduced into the field of molecular and liquid crystals. The technique allows fast time-resolved X-ray diffractograms to be recorded simultaneously with the recording of heat flow into or out of the specimen during a heating, cooling or isothermal scan. Structural transformations, as revealed by changes in the diffraction pattern, can thereby be unambiguously correlated with thermal events such as endo-or exo-therms or changes in heat capacity. Small and wide angle diffraction can be monitored. Sample pans and cuvettes made of boron nitride or graphite are used, both materials combining high transparency for X-rays with good thermal conductivity. Selected examples of application of the technique are presented.