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Abstract  

In isoperibol temperature-rise calorimetry, different approaches can lead to the corrected temperature rise. The description of the methodology, as well as an improvement in the approach to the accurate numerical calculation of the corrected temperature rise in isoperibol calorimetry, based on the comparison between the exponential functional description of the initial and final periods and an independent third order polynomial fitting, is presented. The latter is focused on the strategy of minimizing the result dependency on the definition of the main period of the reaction. Furthermore, the dedicated software application Labtermo is introduced.

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Abstract  

In high pressure calorimetry the pressure change is used to obtain the desired phenomenon (i.e. phase change) at constant temperature. Two high pressure calorimeters have been developed to measure the latent heat of fusion of pure water (hexagonal ice-type I) at subzero temperature. Both calorimeters used a constant pressurisation rate produced with a high pressure pump driven by a step motor. The first calorimeter was a single cell calorimeter where mercury acted as the pressurisation fluid, while the second one was differential (two cells) and was pressurised with pentane. Both calorimeters gave high accuracy data of latent heat of fusion of pure water, which were determined taking into account that either the fluid used to pressurise or the pressurisation rate affected the calorimetric signal.

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Abstract  

A new conceptual approach is proposed for evaluation of the most important properties of cement-containing composites on the basis of the rate and degree off completeness of hardening processes and study of the porous structure during material formation, within the limits of the system “composition-structure-process-property”.

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Calorimetry studies of a chemical oscillatory system

The effect of putrescine on KSCN-H2O2-CuSO4-NaOH reactions

Journal of Thermal Analysis and Calorimetry
Authors: S. Jingyan, L. Yuwen, L. Jie, W. Zhiyong, and W. Cunxin

Abstract  

The effect of putrescine (PUT) on KSCN-H2O2-CuSO4-NaOH oscillating system was investigated by calorimetric method. The oscillating reaction was monitored in a closed reactor with stirring, and the result showed that the oscillating period was linearly related with putrescine concentration and the numbers of oscillation decreased with increase in putrescine concentration. When [PUT]=2.83�10−4 M, no oscillation was observed. A possible mechanism is proposed that putrescine is a scavenger of the active-oxygen species. The result of numerical simulation by a simplified mechanism consisting of 18 kinetic steps and 16 variables is consistent with the experimental findings.

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Abstract  

Heats of explosion of non-ideal RDX-based compositions in four various atmospheres (argon, nitrogen, air and argon/oxygen mixture) were measured. Charges of phlegmatized RDX containing 30% of two types of aluminium powders, coarse aluminium oxide, or fine lithium fluoride particles were fired in a calorimetric bomb of 5.6 dm3 in volume. The influence of inert and reactive additives and the atmosphere filling the bomb on the heat outcome was examined. To estimate the degree of afterburning of the detonation products and reactive particles, thermochemical calculations were also performed for the tested explosive compositions.

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. Calorimetry, being a non specific technique, measures all events that occur during the process of seed germination either of physical or chemical nature. Calorimetry has proven to be useful as monitor for many types of physical, chemical or biological systems

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Introduction The European Symposium on Thermal Analysis and Calorimetry (ESTAC) owes it origins to a decision by the UK Thermal Methods Group (TMG) to hold an international meeting on thermal analysis in the UK, following a

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Application of the calorimetry to studies of colloidal phenomena

Enthalpies of micellization and enthalpies of adsorption of zwitterionic surfactants onto silica gel

Journal of Thermal Analysis and Calorimetry
Authors: J. Zajac, M. Chorro, C. Chorro, and S. Partyka

Abstract  

The importance of calorimetric methods in studies of colloidal phenomena is illustrated by the analysis of the experimental enthalpies of dilution and adsorption for aqueous solutions of three zwitterionic surfactants: 1–12 betaine, 3–12 betaine, and 3–12 sulfobetaine. The batch microcalorimeter ‘Montcal 3’, used to obtain these data, is described. The molar enthalpies of micellization and the differential molar enthalpies of adsorption onto silica gel are shown to be functions of the headgroup hydrophilicity, fixed by the type of negatively charged center and the number of methylene groups separating the charged sites.

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Abstract  

The effect of PbO on cement hydration kinetics by calorimetric method was evaluated as a first step in this project. Substantial retardation of reaction with water at early stages with subsequent intensification of the process was found. As the next step, the model systems covering pure cement minerals and their mixtures of various composition as well as soluble Pb salts were taken into account to elucidate the mechanism of delayed, by quite good formation of products in the so-called post-induction period. The precipitation of sulphate, forming very thin impermeable layer seems to be responsible for this delaying effect in case of cement, however the other reactions of Pb compounds in alkaline environment of hydrating calcium silicate are not out of importance. In order to prove this, the studies of chemical composition in small areas were also carried out.

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