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standard electrode reaction, the standard potential of which is the one corresponding to a reversible electrode reaction. In the electrochemical–calorimetry experiments, it is necessary to measure EPH. Vetter has shown in his book [ 25 ], EPH, as
Abstract
European Conference on Calorimetry and Thermal Analysis for Environment September 6–11, 2005 Zakopane, Poland ECCTAE 2005 Selected Papers
Introduction Being a reliable analysis method for the determination of caloric effects, power compensated differential scanning calorimetry (DSC) was applied to determine the heat of reaction of hydrothermal carbonization (HTC
to its complexity. As the oxidation proceeds, several reactions occur simultaneously at different rates. These reactions release heat that can be measured using differential scanning calorimetry (DSC). Recording the heat released from a particular
A new approach for the estimation of the melting enthalpy of metastable crystalline compounds using differential scanning calorimetry
Application to the two crystallographic forms of Etiracetam
with metastable forms [ 2 ]. Differential Scanning Calorimetry (DSC) is commonly used to evaluate most of the thermal properties of solid states, such as melting temperatures and enthalpies or specific heat capacities [ 3 ]. Whilst recent
Abstract
The use of by-product gypsum is an important alternative in concrete design. In present experiment, conduction calorimetry was applied to investigate the early hydration of calcium aluminate cement (CAC)/flue gas desulfurization (FGD) gypsum paste, supplemented with the determination of setting times and analysis of hydrates by X-ray diffraction (XRD). It was found that different profiles of heat evolution rate were presented depending on the CAC/FGD gypsum ratio. Two distinct exothermic peaks, associating with CAC hydration and ettringite formation respectively, appeared when the FGD gypsum content was less than 20%. Hydrate barrier mechanism was introduced to explain the difference in induction periods of the pastes with or without FGD gypsum. It is concluded that the blending of FGD gypsum accelerates the hydration of CAC for the quick formation of ettringite and generates greater hydration heat from per gram of pure CAC for the high exothermic effect of ettringite formation. The dissolution and diffusion of gypsum plays an important role of reacting controller during the hydrations of the pastes with FGD gypsum. The modified hydration process and mechanism in this case is well visualized by means of calorimetry.
Abstract
To use flue gas desulfurization (FGD) gypsum and limestone as supplement of cement, conduction calorimetry was applied to investigate the early hydration of ternary binder of calcium aluminate cement (CAC), Portland-limestone cement (PLC), and FGD gypsum, supplemented with the determination of setting times and X-ray diffraction (XRD) analysis. Different exothermal profiles were presented in two groups of pastes, in which one group (group A) sets the mass ratio of FGD gypsum/CAC at 0.25 and the other group (group B) sets the mass ratio of PLC/CAC at 0.25. Besides the two common exothermal peaks in cement hydration, a third exothermal peak appears in the pastes with 5–15% FGD gypsum after gypsum is depleted. It is found that not PLC but FGD gypsum plays the key role in such ternary binder where the reaction of ettringite formation dominates the hydration process. PLC accelerates the hydration of ternary binder, which mainly attributes to the nucleating effect of fine limestone particles and PC clinker. The modified hydration process and mechanism in this case is well visualized by the means of calorimetry and it helps us to optimize such design of ternary cementitious material.
Abstract
This work reports a non-isothermal kinetics of the melting and the nematic to isotropic (N–I) phase transitions of the pentylcyanobiphenyl (5CB) liquid crystal compared with octylcyanobiphenyl (8CB) liquid crystal using calorimetric technique. Temperature scans and heating rate scans were performed for 5CB and 8CB from 280 to 333 K at various rates using differential scanning calorimetry from 0.5 to 20 K min−1. Double activation was observed for 5CB for two heating rate regimes whereas 8CB indicated single activation only. The 5CB has smaller enthalpy and entropy of the transitions and needs larger activation than 8CB. This kinetic change can be explained in terms of the length scale and mobility of the liquid crystal molecules.
Abstract
The mathematical-physical equation concerning the process of calorimetry of electrode reactions was deduced, and the corresponding solutions were obtained respectively for the period of the electrochemical polarization and that of the natural cooling. The calorimetry of the anodic oxidation of ferrocyanide to ferricyanide under linear sweep-current polarization was carried out, the obtained apparent enthalpy change of the electrode reaction agreed well with that obtained by the calorimetry with constant currents. The developed calorimetry with linear sweep-current and the data processing method are applicable for quick determination of apparent enthalpy changes of electrode reactions.
Abstract
October 2–5, 2005 Congress Center ACADEMIA Star Lesn, Slovak Republic Guest Editor: Peter Šimon Organizers — Slovak Group of Thermal Analysis and Calorimetry Slovak Society of Chemistry Faculty of Technology and Food Technology, Slovak University of Technology Slovak Silicate Society Selected Papers
