Thermal decompositions of NaClO4 and KClO4 were followed by simultaneous TS-DTA and thermomicroscopy. For NaClO4 TS curves corresponding to melting/decomposition and solidification of molten NaCl were found to consist of six peaks. During
decomposition of KClO4, three TS peaks appeared. The origin of these TS peaks is discussed on the basis of thermomicroscopic observations during
which melting of the particles, evolution of bubbles of different sizes, formation of solid products of varied morphologies,
vigorous vibration of these solids, and precipitation of NaCl or KCl were observed.
Sample controlled thermal analysis techniques such as constant rate transformation analysis or stepwise isothermal analysis,
where the transformation rate of the sample itself is used to control the experiment, are becoming increasingly important
. The measurements are normally carried out using changes in the sample mass, sample dimensions or in the evolved gas,
as the property used to control the experiment, and enable reactions to be studied in greater detail than is possible using
linear heating techniques. A new approach is described here where a thermomicroscopy system has been developed to enable the
intensity of the light reflected or transmitted by the sample to be used as the controlling signal .
The correlation between morphological changes and DSC recordings gives valuable information on the mechanism of phase transformations. The present paper describes a new instrument for simultaneous DSC and thermomicroscopy in transmitted light, where a DSC device is placed in a commercially available hot-stage. The application of this DSC/thermomicroscopy is exemplified by study of the phase diagrams for KNO3-NaNO3, diphenylamine-benzophenone and a liquid crystal system.
Thermal characteristics of eight crude oils and their treatment with additives were studied by differential scanning calorimetry
(DSC), thermomicroscopy, viscometer and pour point tester. Different additives were found as more effective for different
type of crude oils depending on the wax content. Crude oils showed a reduced pour point after treatment with additives. Effects
of different additives were also discussed by analysing the DSC curves and thermomicroscopy result.
The physicochemical characterization of the solid-state enantiomers and racemate of efaroxan hydrochloride (C13H17N2O+Cl-,
M=252.5 g mol-1) was performed by thermoanalytical methods (differential scanning calorimetry, thermogravimetry and thermomicroscopy)
and spectral methods (infrared spectrometry and X-ray diffractometry).
The efaroxan enantiomers and racemate were shown to be unstable near the melting point. At the beginning of the decomposition,
a loss of hydrogen chloride was observed. However when sealed pans were used, the compounds decomposed at higher temperature,
allowing a precise evaluation of the melting enthalpies by means of differential scanning calorimetry. The nature of the racemate
and its thermal stability were assessed by evaluating its free formation enthalpy. An enantiotropic solid-solid transformation
(II→I) was noted for the racemate; the reverse process (I→II) follows zero-order kinetics.
The binary systems of cholesteryl nonanoate with 4,4′-bis(hexyloxy)azoxybenzene (1) and with 4,4′-bis(heptyloxy)azoxybenzene (2) show induced smecticA phases with transition point maximum. Whereas in (1) the smecticA phase is transformed into the cholesteric phase on heating within the whole range of its existence, in (2) the maximum of the smectic phase is stabilized compared with the cholesteric phase and clears into the isotropic melt directly. The molecular ratio of the maximum is 1∶1 in both cases. Moreover in system (2) a smecticC phase was observed.
It has been shown that simultaneous measurements of reflected light intensity (RLI) with DSC can give additional and valuable
information for the thermal analysis of materials including pure organic and inorganic chemicals, natural and synthetic polymers
This paper extends the range of polymers studied and examines the possibility of improving the reproducibility and quantitative
nature of RLI measurements. Polymer crystallisation, the curing of epoxy resins, the action of fire retardant additives and
the degradation of polymers and proteins are among the systems studied.
The binary systems of urea with polyethylene glycols 6000 and 4000 show inclusion compounds with higher melting points than
the two components (m.p. 143 and 142.5°C resp.). From the melt unstable forms crystallize beside the stable crystal modifications. These have also
been identified by FTIR microscopy and X-ray powder diffractometry. The phase diagrams are uncommon in so far as the inclusion
compounds do not form eutectics but monotectics with both components. The inclusion compounds of the two polyethylene glycols
with urea are isomorphous and form a series of mixed crystals following the Roozeboom I type of diagram.
include IR spectroscopy, X-ray diffraction, thermomicroscopy, and thermal methods, including differential scanning calorimetry [ 13 , 14 ].
The potential drugs studied in this article correspond to organosulfur and organoselenium compounds with