The flexibility of the internal structures of solids, both crystalline and amorphous, is a result of the freedom of the displacement
of their elements, without disturbance of the continuity of the structure as a whole. This article discusses peculiarities
of solids with flexible structures. The effects of flexibility in the thermal reactions of the creation of new compounds in
the internal structure of solids, and the phase transitions, are considered. Flexibility is indispensable for random amorphous
structure formation. The glass transition effect is a consequence of the high flexibility of the structure of glasses.
Authors:Y. Xu-Wu, Z. Hang-Guo, S. Wu-Juan, W. Xiao-Yan, and G. Sheng-Li
The copper(II) complex of 6-benzylaminopurine (6-BAP) has been prepared with dihydrated cupric chloride and 6-benzylaminopurine.
Infrared spectrum and thermal stabilities of the solid complex have been discussed. The constant-volume combustion energy,
ΔcU, has been determined as −12566.92±6.44 kJ mol−1 by a precise rotating-bomb calorimeter at 298.15 K. From the results and other auxiliary quantities, the standard molar enthalpy
of combustion, ΔcHmθ, and the standard molar of formation of the complex, ΔfHmθ, were calculated as −12558.24±6.44 and −842.50±6.47 kJ mol−1, respectively.
The hydrated rare earth orthophosphates LnPO4 ·xH2O (Ln=La-Dy) contain zeolitic water in the structural channels, which is released reversibly up to 300°. The thermal stabilities of the hydrates depend upon the nature of the Ln atom. The dehydration temperature decreases with decreasing ionic radiusr of Ln3+, according to the general equationθ=(r−a)/b (whereθ is the DSC and/or DTG dehydration peak temperature, anda andb are empirical constants depending on the experimental conditions).
Authors:V. Ovchinnikov, E. Sagadeev, L. Lapteva, L. Khasieva, M. Alikberov, E. Sitnikova, I. Antipin, I. Stoikov, and A. Konovalov
The enthalpies of vaporization of different classes of phosphorylated alcohols and amines were determined from their enthalpies
of solution in hexane and carbon tetrachloride. The enthalpies of specific (hydrogen-bond) interaction with the solvents (chloroform
and pyridine) of derivatives containing X-H groups (X=O or N) in the α-position to the P=O group were determined. The results
were explained in terms of the spatial structure of such compounds.
Authors:M. R. Bissengaliyeva, L. P. Ogorodova, L. V. Mel'chakova, and M. F. Vigasina
Thermal and thermochemical investigations of natural hydroxyl-bearing copper sulfate Cu3SO4(OH)4—antlerite have been carried out. The stages of its thermal decomposition have been studied employing the Fourier-transform IR spectroscopy. The enthalpy of formation of antlerite from the elements ΔfHmo (298.15 K) = (−1750 ± 10) kJ mol−1 has been determined by the method of oxide melt solution calorimetry. Using value of Smo (298.15 K), equal to (263.46 ± 0.47) J K−1mol−1, obtained earlier by the method of adiabatic calorimetry, the Gibbs energy value of ΔfGmo (298.15 K) = (−1467 ± 10) kJ mol−1 has been calculated.
The mixing and melting enthalpy of the binary system nitrocellulose+2,6-dinitrotoluene was determined using the DSC method.
The mixing enthalpy of the components was calculated. At the melting temperature the maximum value of the mixing enthalpy
for the mole fractionxw26DNT=0.607 is equal HMmax= −3.41 kJ mol−1. Measurements of the melting process (second measurement) were conducted after a storage period of several days at room temperature.
Analysis of the melting peaks shows that the melting process of 26DNT takes place in pores of the micro-fiber and bulk outside
the fibers. In the case of a mass fraction of xw26DNT>0.9 the melting process takes place in the bulk, which suggests that in the case of such concentrations separation of the
A method of gelation enthalpy determination of nitrocellulose (NC)+s-diethyldiphenylurea (Centralite 1, C1) binary system
was elaborated using the change of Centralite 1 melting enthalpy in the mixture. The heats of C1 melting together with gelation
and dissolution of NC fibres were determined by DSC calorimetric methods. A sharp maximum of the gelation enthalpy for C1
mole fraction xC1max
=0.555 suggests that the complex is very stable and one partly nitrated anhydroglucose ring is interacting with about 1.25
C1 molecules. The gelatinization enthalpy maximum equals