The enthalpies of formation of 13 calcium silicates, aluminates, alumino-silicates and ferro-alumino-silicates were measured
by dissolution calorimetry with the help of a high-temperature Calvet calorimeter. Dissolution experiments were performed
in a lead metaborate (2PbO−B2O3) baths at 1173 K.
The synthesis of the samples was realized by melting together pure silica, alumina, ferric oxide and calcium carbonate in
appropriate ratios. The samples obtained in this way were examined by X-ray diffraction and scanning electronic microscopy.
The free lime content was also determined by chemical analysis.
The enthalpy of formation of silicates and aluminates obeys two different linear relations with respect to the ratio Ca/X
(X=Al or/and Si) except for Ca12Al14O33 which does not exist in its pure form but has to be stabilized by anions as OH− or Cl−. The data corresponding to the two aluminosilicates are located between these lines. The enthalpy of formation of tricalcium
silicate (Ca3SiO5 i.e. C3S according to the Bogue terminology) from dicalcium silicate and lime could be calculated as −6kJ·mol−1. This reaction is the most important one in the industrial process of clinkerization.
The standard molar enthalpy of formation of crystalline di-isobutyldithiocarbamate complexes of P, As, Sb and Bi(III) has
been derived by solution calorimetry at 298.15 K. The corresponding standard molar enthalpies of sublimation were estimated
by means of differential scanning calorimetry. From the standard molar enthalpies of formation of the gaseous chelates the
homolytic and heterolytic mean metal-sulphur bond-dissociation enthalpies were calculated.
Traditionally, the kinetic treatment of adiabatic calorimetry data has been based on the results of one or more experiments, but always with the assumption of the kinetic model that the reaction follows to calculate the kinetic parameters. In this paper a method for the determination of the activation energy that uses a set of adiabatic calorimetry data is developed. To check the method, the thermal decompositions of two peroxides were studied.
Thermodynamic investigations of Ga-GeSb0.855 section in the ternary system Ga-Ge-Sb, which is of a practical importance in electric-industry, are presented in this paper.
Results of a comparative thermodynamic analysis at 1273 K obtained by Oelsen calorimetry and predicting methods - general
solution model and Hajra's method are also given.
Adsorption isotherms of n-butane on a granulated activated carbon were measured by two different but complementary experimental
methods: calorimetry and gravimetry. Adsorption heats were determined in different ways. For the system studied, the experimental
results prove that the adsorbent offers a homogeneous site distribution. Besides, there can be differences between the adsorption
heat values which might come from the way they are obtained (by calculation or direct measurements).
The enthalpies of mixing of liquid Gd-Si (17705 K) and Al-Gd (17605 K) alloys have been measured by high-temperature isoperibolic
calorimetry. The calorimetric study of the gadolinium-based liquid alloys demonstrates the great negative enthalpies of mixing,
which is associated with the contribution of GdSi and GdAl2 intermetallides into the liquid-state thermodynamics. The comparison of obtained results with literature data has been performed.
High-temperature differential scanning calorimetry was used to investigate the thermodynamic parameters of the γ–β and β–α
transitions in calcium pyrophosphate (Ca2P2O7). The measured enthalpy of transition compared well with previous results when higher heating rates (≥20 K min−1) were used. Recommendations for optimal use of HTDSC in high-temperature phase transition measurements are presented.
Differential scanning calorimetry was used to study the stability of omeprazole in two forms: granules and powder. The drug
was subjected to light, elevated temperature (40 and 60�C) and different pH values. The greatest alterations in stability
were caused by pH, followed by light.
The physical aging characteristics of maltose glasses aged at two temperatures below the glass transition temperature, Tg, (Tg-10C and Tg-20C) from 5 to 10 000 min were measured by standard differential scanning calorimetry (SDSC) and modulated differential
scanning calorimetry (MDSC). The experimentally measured instrumental Tg, the calculated Tg, and the excess enthalpy values were obtained for aged glasses using both DSC methods. The development of excess enthalpy
as a function of aging time, as measured by both SDSC and MDSC, was fit using the Cowie and Ferguson and Tool-Narayanswamy-Moynihan
models. The change in the Tg values and the development of the excess enthalpy resulting from physical aging measured by the two DSC methods are discussed.
The mixing enthalpies of blends of polymethylmethacrylate (PMMA) with poly(styrene-co-acrylonitrile) (SAN) were investigated
by analogue calorimetry through the determination of the excess enthalpies of pseudobinary model mixtures corresponding to
the addition of methyl-i-butyrate to a binary mixture of acetonitrile or propionitrile plus toluene or ethylbenzene.
A group contribution procedure, based on UNIQUAC equation, was also devised and the polymeric mixing enthalpies were calculated
from properly defined group contributions. Enthalpies for polymeric interactions were introduced into the Flory-Huggins equation
and the miscibility window of PMMA-SAN mixtures was calculated.
The results show a qualitative agreement with the experimental miscibility data and indicate that both the analogue calorimetry
and the group contribution procedures yield correct results when acetonitrile, and not propionitrile, is chosen as the model
for the polyacrylonitrile repeat unit of the copolymer.