When the DTA of polystyrene is carried out in air in a platinum sample holder, an anomalously high endothermic effect is observed. This effect was found to be related to gas-phase catalytic styrene oxidation occurring on the surface of both operating and reference platinum sample holders. Methodological recommendations are given concerning the DTA procedure for organic substances, making it possible to avoid this type of anomaly.The thermal degradation of polystyrene (PS) has been fairly well investigated. It is known that this process occurs mainly as depolymerization, as a result of which the initial monomer, styrene, is evolved:to the accompaniment of an endothermic effect [1,2]. In fact, if analysis is carried out in a ceramic crucible in a static atmosphere of air (derivatograph, heating rate 10 deg/min, sample weight 50 mg), the DTA curve of powdered PS exhibits a weak endothermic peak with a maximum at 394 ~ followed by two small exothermic peaks with maxima at 420 and 542 ~ (Fig.
Complexes of bis(N-phenyl)-pyromellitic acid diamide with dimethylformamide were synthetized and studied by thermal mass-spectrometry. It was found that, depending on the precipitating agent applied, the composition of the complexes corresponded to 1 acid amide: 2 dimethylformamide or to 1 acid amide: 1 dimethylformamide. The effects of complex formation on the thermal cyclodehydration of bis(N-phenyl)pyromellitic acid diamide and on the accompanying degradation processes are discussed.
A study was made of the effects of organic carbonyl-containing compounds and inorganic acids on the character of complex formation of the solvent with polyacid amides, and in particular on the frequency of three-dimensional networks formed by hydrogen-bonds in solid polyacid amide films. It was found that the characteristics of the solid-phase cyclodehydration process can be varied within a wide range by means of active additives.
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