The study of 'DSP' binding systems by thermogravimetry and differential thermal analysis

The so-called DSP (Densified Systems containing homogenously arranged Particles) systems represent a high-performance class of inorganic binders. The hydration and hardening processes of some DSP systems, based on calcium silicates (C₃S and C₂S) or Portland cement/clinker with silica fume additions, were assessed, in this paper, using the thermogravimetry (TG) and differential thermal analysis (DTA). These data permit a qualitative and quantitative study of the formed hydrates as well as the estimation of hydration process kinetics. This revised version was published online in August 2006 with corrections to the Cover Date.     

A multi-analytical approach to studying binding media in oil paintings

This article presents a multi-analytical approach to investigating the drying, polymerisation and oxidative degradation of linseed oil, which had undergone various treatments known to be undertaken during the nineteenth century in preparation for painting. The oil was mechanically extracted from the same seed lot then processed by different methods: water washing, heat treatments, and the addition of driers, with and without heat. The oil was prepared in 1999 within the framework of the MOLART project. We compared thermogravimetric analysis (TG), which yields macromolecular information, with gas-chromatography mass-spectrometry (GC/MS) and direct exposure mass spectrometry (DE-MS), which provide molecular information. This comparison enabled us to elucidate the role of pre-treatment on the composition of the oil. TG and oxygen uptake curves registered at a constant temperature helped us to identify the different physical behaviour of the oil samples, thus highlighting the presence of hydrolysed, oxidised and crosslinked fractions, as a consequence of the different pre-treatments. GC/MS was used to characterise the soluble and non-polymeric fraction of the oil, to calculate the ratios of palmitic to stearic acid (P/S), and azelaic to palmitic acid (A/P), and to further evaluate the effects of oil pre-treatments. DE-MS using chemical ionisation with CH₄, enabled us to establish the chemical composition of the oil in different stages of ageing. DE-MS proved to be a useful tool for a simultaneous semi-quantitative characterisation of the free fatty acids, monoglycerids, diglycerides and triglycerides present in each sample. The combination of thermal analysis with GC/MS and DE-MS enabled a model to be developed, which unravelled how oil pre-treatments produce binders with different physical–chemical qualities.     

Attempts to apply differential thermal analysis with thermogravimetry for the investigations of asphalt-polymer systems

Attempts were made to apply DTA together with TG for the investigation of asphalt-poly(methyl methacrylate) systems. Compositions were made by photopolymerization of methyl methacrylate in the presence of asphalt or asphalt components.The value of thermal analysis was demonstrated especially for determining the structures asphalt-polymer systems.

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Zusammenfassung Versuche wurden unternommen, um DTA und TG zur Untersuchung von Asphalt-PMM-Systemen heranzuziehen. Die in dieser Arbeit untersuchten Kompositionen wurden durch Photopolymerisation von in Asphalt oder Asphaltkomponenten eingebrachtem MM hergestellt. Die thermische Analyse ist besonders zur Bestimmung der Struktur von Asphalt-Polymer-Systemen geeignet.

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Purity determinations by differential thermal analysis

Measurement of the melting-point depression of impure samples was compared with a differential method that involved running the impure sample against a pure sample of the same material. Samples of highly purified benzophenone to which had been added known quantities of 4-methylbenzophenone were studied. The area under the curve was proportional to the difference in purity between the sample and reference material over the range studied, 0.3-2.0 mole % with a standard deviation of 0.10 mole %, an uncertainty only half as large as one obtained by the melting-point depression method with the same apparatus.     

Camphor cryoscopy by differential thermal analysis

The determination of the freezing point depression of organic solutions with camphor as solvent was performed by means of DTA. Amounts of 50–100μg substance and 1–2 mg camphor were weighed on a platinum wire, the camphor being pressed to a pellet by a glass press. The temperature difference between the glass tubes with pure camphor and with solution was recorded versus temperature, while the samples were cooled in a previously heated aluminium block. The difference between the recorded deviations from a straight line was found to be a measure of the freezing point depression. Errors less than 5 % were computed for various samples.     

Investigation of imidization by differential thermal analysis

The DTA method has been used to show that, in the imidization of polyamido acid in solution in dimethylformamide, there is not only dehydrocyclization but also interaction of the solvent with reactive groups of the polyamido acid.     

Characterization and analysis of waxes by differential thermal analysis

The characterization of waxes by differential thermal analysis is described. An endothermic peak at 475-480 degrees is characteristic of microcrystalline and polyethylene waxes, and measurement of its area provides a method for the estimation of these waxes in mixtures.     

Investigation of catalytic activities by differential thermal analysis

A calorimetric method is proposed to evaluate the catalytic activity of a solid catalyst with respect to the exothermic oxidation of Volatile Organic Compounds (VOC).This method employs a differential thermal analyzer in which an inert reference and a catalytically active sample are both fluxed at a constant rate with a reactive gaseous mixture composed of an inert gas (N₂ 90% vol.), oxygen and VOC, the last typically 900 to 5000 ppm. While the temperature is varied according to a predefined cycle, the output signal due to the exothermic reaction on the catalyst is continuously recorded. The design of the test chamber, the amount of catalyst, the shape of the holders and finally the flow rate and composition of the gaseous mixture should be carefully selected in order to achieve reproducible results.     

Quantitative estimation of magnesite by differential thermal analysis

A method for quantitative estimation of magnesite in magnesite-rich rocks by differential thermal analysis, using magnesium hydroxide as internal standard, is presented. The effects of variations due to particle size and impurities are discussed.     

Dielectrical differential thermal analysis

Sodium faujasites with different Si/Al ratios were studied by means of thermodielectrical method.     

Dielectric differential thermal analysis

Thermodielectric analysis has been used to test some very well-characterized kaolins from Cuban deposits. The samples were analysed by thermal analysis, X-ray diffraction, infrared spectrometry, electron microscopy and chemical analysis.The dielectrical thermograms show that the most evident effect for the hydrated versions is the water peak. The second dielectric effect, at high temperatures, is related to the cationic conductions. A relation involving the K content of the sample was observed.

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Zusammenfassung Mittels thermodielektrischer Analyse wurden einige gut charakterisierte Kaoline aus kubanischen Lagerstätten untersucht. Die Proben wurden mittels Thermoanalyse (TA), Röntgendiffraktion (XRD), Infrarotspektroskopie (IR), Elektronenmikroskopie (EM) und Elementaranalyse untersucht. Die Dielektrothermogramme zeigen, daß bei den hydratierten Versionen der augenscheinlichste Effekt der Wasserpeak ist. Der zweite dielektrische Effekt bei höheren Temperaturen wird mit der Kationenleitung in Zusammenhang gebracht, wodurch es möglich wird, Informationen über den K-Gehalt der Proben zu erlangen.

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Dielectric differential thermal analysis

Dithionates (CaS₂O₆·4H₂O, SrS₂O₆·4H₂O, BaS₂O₆·2H₂O, MnS₂O₆·4H₂O, MgS₂O₆·6H₂O, CoS₂O₆·6H₂O, NiS₂O₆·6H₂O, ZnS₂O₆·6H₂O and CuS₂O₆·4H₂O) were subjected to thermodielectric analysis. The thermoanalytical curves show low temperature effects from 60 to 350°. These are related with the dehydration and decomposition of the dithionates, which could be fully correlated with the knowledge of the thermal behavior of these compouds obtained with other thermal methods.     

Dielectric differential thermal analysis

The present paper deals with the role of guest molecules in the moleculer sieves systems.     

Use of near infrared spectroscopy in a study of binding media used in paintings

The present study illustrates the use of near infrared spectroscopy in the conservation and restoration field. This application of the technique, widely used in other fields such as the agricultural and food industries, is very interesting due to two of its features: rapidity and non-destructiveness. In this study, three classification algorithms have been used to attempt to correlate the spectra of the samples under study—mixtures of two pigments (one organic and the other inorganic)—with binder recipes found in literature. Some of these recipes have very similar compositions, but they were distinguished into groups, depending on the painting technique associated with them.     

Measurement of the oxidative stability of polyethylene by differential thermal analysis

An evaluation has been made of the experimental features critical to the evaluation of the oxidative stability of polyethylene using constant temperature DTA, with particular reference to the control and measurement of the sample temperature.     

Studies of calcium orthosilicate polymorphism by differential thermal analysis

The polymorphic transitions of calcium orthosilicate have been studied by means of differential thermal analysis. The parameters of-Ca₂SiO₄ synthesis without stabilizers haye been established.

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Zusammenfassung Mittels DTA wurden die Polymorphieübergänge von Kalziumorthosilikat untersucht. Die Parameter zur Synthese von-Ca₂SiO₄ ohne Stabilisatoren wurden bestimmt.

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Thermogravimetric and differential thermal analytical investigations on sewage farm soils

Soil substrates of sewage farms (inflow of sewage areas) and of closed sewage farms were investigated by means of thermogravimetry and differential thermal analysis. The results were compared with those obtained for control samples from outside the sewage farms.The organic matter of actively used sewage areas (inflow) contains a remarkable amount of easily oxidizable compounds brought to the inflows by suspended matter.Beside these compounds, macromolecular organic substances predominate in the composition of the organic matter and are responsible for an immense heat release in the high temperature range of the thermal studies.In the substrates of closed sewage farm inflows or of other sewage farm areas which do not belong to the inflows, the amounts of volatile and easily oxidizable compounds decrease rapidly. The substrates hardly differ in their reaction temperatures from control samples. The influence of single macromolecules on the exothermic oxidation is reduced with increasing humification.