Dresden 2017 – wissenschaftliches Programm
CPP 49.10: Poster
Mittwoch, 22. März 2017, 18:30–21:00, P2-OG1
Sublimation enthalpy and vapor pressure of thermally instable substances from fast scanning calorimetry — •Amir Abdelaziz, Dzmitry Zaitsau, Sergey Verevkin, and Christoph Schick — University of Rostock, Germany
The determination of vapour pressure and corresponding enthalpy of sublimation lay within focus of many scientific fields and industrial applications. These values directly connected to the intermolecular forces in crystal state, provides the lattice energy and change in ordering by going from crystal to gas phase. In the present study the fast scanning calorimetry was successfully applied for determination of vapour pressure and enthalpies of sublimation of low volatile organic substances. In many cases investigation of such systems is accomplished with low thermal stability of them and application of classic techniques often fails by determining the decomposition rate of the system. The technique is based on the determination of the mass loss rate of the sample from the experimental total heat capacity and preliminary determined specific heat capacity of the compound under study. Sublimation of the sample is carried out during repeated isotherms of pre-defined duration and at selected temperatures. Sample is heated to needed temperatures at high heating rates accessible by this technique, what allows reaching the sublimation temperatures without any mass loss during the heating time. From the other side in the proposed technique the sublimation area is so big that sublimation mass loss rate is incomparably higher that decomposition rate. Thus the sample of tenth nano grams sublimes without any thermal degradation.