In our laboratory, the synthesis of new inorganic pigments is followed by thermal analysis using a Derivatograph apparatus.
The first information about the temperature region of the formation of the pigments investigated is provided by thermal analysis.
The main attention is directed to the preparation of high-temperature colour pigments, lightfastness colour pigments, anticorrosive
pigments, new ecological inorganic pigments and luminescent pigments. All inorganic pigments are useful for colouring of ceramic
glazes, enamels, plastics, paints, cements and other building systems. The synthesis of all these pigments is based on temperature
calcination of starting materials. Tens of new inorganic pigments have been prepared thanks to methods of thermal analysis.
These synthesis are described in more than 100 Czech patents.
Derivatograph Q-1500D was completed with a partial vapour pressure control unit in order to study the sorption phenomena. The proposed arrangement allows to perform time consuming experiments at ambient atmospheric pressure in the temperature range 10–200°C.
A Q-derivatograph was used for quantitative studies on low-melting compounds. The apparatus was calibrated with four selected compounds. Their melting temperatures were between 30 and 90°, while their melting enthalpies were known from the literature and were verified by DSC. The calibration curve turned out to be a straight line, and a mean calibration coefficient was determined between 30 and 90°. The Q-derivatograph was then applied for quantitative studies of oligoethyleneadipate (OEA-2000), with a melting temperature between 46 and 55°, depending on its crystal form. The values ofΔHm depended on its morphological form, which was associated with the magnitude of the internal stresses.
The effects of ageing for periods of one month and one year upon chemically preoxidized and radiation-sterilized oxycellulose were investigated. Changes in chemical structure and energetic excitation of atomic groups of the oxycellulose skeleton were evaluated from qualitative and quantitative aspects. Use was made of numerical interpretation of activation energy quantities, weight losses, the quantitative energetic quantity EW, and thermal effects (areas of DTA curve peaks) of individual degradation reactions, when applying the oxidation pyrolysis method with a Derivatograph.
Studies of water adsorption and desorption on silica gel with a modified derivatograph are described. The dynamic gas chromatography step profile method was used to determine isotherms of adsorption and desorption from the TG curve. The obtained isotherms agree with those from other methods. The properties of surface liquid layers can be investigated by this method.
Authors:J. Zsakó, G. Liptay, Cs. Várhelyi, and E. Brandt-Petrik
The thermal decompositions of 8 complexes of the type A · H[Cr(NCS)4(am)2] (A=NH3, pyridine,α-picoline or aniline, andam=NH3 or aniline) and of 14 complexes of the type M[Cr(NCS)4(am)2] (M=K, Ag, Tl, 1/2 Cd, 1/2 Pb or 1/3 Bi, andam=NH3, benzylamine or aniline derivatives) were studied by means of a derivatograph. In the case of the A · H salts the formation of Cr(NCS)3 was observed as a labile intermediate. Characteristic temperatures are discussed in terms of the polarizing effect of the outer sphere cations and of the nucleophilic character of the ligands. The results are compared with those obtained in the thermal decompositions of the analogous salts of the complex acid H3[Cr(NCS)6].