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31.
Allais C. Keller G. Lesieur P Ollivon M. Artzner F. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):723-728
Polymorphism of trilaurin mixed with 4% of cholesterol was studied with a setup coupling calorimetry and phase characterisation
by in-situ X-ray diffraction (Microcalix). Four polymorphic forms were identified. Monotropic and enantiotropic transitions
were identified from the reconstruction of Gibbs free energy diagram which allows the control of trilaurin polymorphism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
32.
Titration calorimetry was used to construct the solid-liquid equilibrium line in ternary systems containing the solute and an aqueous mixed solvent by measuring the heat of dissolution of the solid solute during successive additions of the liquid solvent. The plot of cumulated heats versus the mole ratio, nsolvent/nsolute, yields two (almost) linear increases of different slopes. These two lines represent successively the enthalpy of dissolution then the enthalpy of dilution of the medium; their intersection gives the solubility and the enthalpy of dissolution of the solute. Phase diagrams have been established over the whole concentration range for o-anisaldehyde, 1,3,5-trimethoxybenzene and vanillin, in water + methanol, +ethanol, or +n-propanol at 303, 313 and 318 K. 相似文献
33.
Grell D. Grell E. Bugnon P. Dietrich B. Lehn J.-M. 《Journal of Thermal Analysis and Calorimetry》2004,77(2):483-495
The coordination of divalent and monovalent inorganic anions to synthetic polyammonium receptors is investigated in aqueous
solution around neutral pH by titration calorimetry and NMR spectroscopy. High-affinity 1:1 complexes are formed by a pyrrole
type cryptand (1) with sulfate and phosphate, characterized by association constants of almost 107 M-1. Affinities close to 105 M-1 are found for polyazacryptands (3 and 4) exhibiting F-/Cl- selectivity. The binding affinities and the anion selectivities are mainly caused by the charges of ligands and anions, which
is discussed on the basis of simple calculations of the electrostatic contribution to the anion/receptor interactions. The
binding of all investigated anions is exothermic at 298.2 K. The contribution of the large negative ΔH values to the free
energy of anion binding of the pyrrole type ligand is partially compensated by marked negative ΔS values. These unfavorable
entropic contributions are attributed to the additional inclusion of water molecules in the anion/receptor complexes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
34.
Thermal behaviour of a polyhedral oligomeric silsesquioxane with epoxy resin cured by diamines 总被引:1,自引:0,他引:1
Ramírez C. Abad M. J. Barral L. Cano J. Díez F. J. López J. Montes R. Polo J. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):421-429
A new material belongs to the family of polyhedral oligomeric silsesquioxanes, the 1-(3-glycidyl) propoxy-3,5,7,9,11,13,15-isobutylpentacyclo-[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane
(glycidylisobutyl-POSS) is characterized by differential scanning calorimetry, thermogravimetric analysis and atomic force
microscopy. Epoxy systems based on diglycidyl ether of bisphenol A (DGEBA) cured with the diamines, 4,4'-diamine-diphenylmethane
(DDM) and 1,4-phenylenediamine (pPDA), were kinetically studied by differential scanning calorimetry in isothermal and dynamic
modes. The thermal behaviour of these systems as the glycidylisobutyl-POSS was added, is discussed later.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
35.
Atsushi Ikeda Masaru Kawaguchi Yoshio Suzuki Tsukasa Hatano Munenori Numata Seiji Shinkai Akio Ohta Makoto Ohta 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):163-170
The calixarene-fullerene interaction,which causes only a slight change in the absorptionspectra, has been substantiated by calorimetricmeasurements: the H° values arecomparable with those obtained from the associationconstants estimated by a spectroscopic method. Furthermore, we determined the association constantbetween homooxacalix[3]arene and [60]fullerenederivatives with a porphyrin moiety by fluorescencespectra. 相似文献
36.
利用精密自动绝热热量计直接测定了配合物Zn(Phe)(NO3)2·H2O(s) (Phe:苯丙氨酸)在78-370 K温区的摩尔热容. 通过热容曲线的解析得到该配合物的起始脱水温度为, T0=(324.27±0.37) K. 将该温区的摩尔热容实验值用最小二乘法拟合得到摩尔热容(Cp, m)对温度(T)的多项式方程, 并且在此基础上计算出了它的舒平热容值和各种热力学函数值. 依据Hess定律, 通过设计热化学循环, 选择体积为100 mL浓度为2 mol·L-1 的盐酸作为量热溶剂, 利用等温环境溶解-反应热量计分别测定混合物{ZnSO4·7H2O(s)+2NaNO3(s)+L-Phe(s)}和{Zn(Phe)(NO3)2·H2O(s)+Na2SO4(s)}的溶解焓为, ⊿dH0m,1 =(69.42±0.05) kJ·mol-1, ⊿dH0 m,2 =(48.14±0.04) kJ·mol-1, 进而计算出该配合物的标准摩尔生成焓为, ⊿fH0m =-(1363.10±3.52) kJ·mol-1. 另外, 利用紫外-可见(UV-Vis)光谱和折光指数(refractiveindex)的测量结果检验了所设计的热化学循环的可靠性. 相似文献
37.
N. A. Yakovleva S. N. Klyamkin O. A. Veremeeva A. A. Tsikhotskaya 《Russian Chemical Bulletin》2005,54(1):135-140
Using heat conducting Tian—Calvet calorimetry and volumetric measurements, the first hydrogen absorption—desorption cycles in the LaNi5-H2 and CeNi5-H2 systems were studied. The pressure—composition isotherms were plotted, the equilibrium pressures of hydrogen along the absorption and desorption branches and in the region of hysteresis for different activation steps were determined, and the enthalpies of phase transitions α → β and β → α were calculated. The profiles of the heat evolution curves were analyzed. It was concluded that the mechanism of the reactions studied changes upon activation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 134–139, January, 2005. 相似文献
38.
The thermodynamic quantities associated with ionization of the N1 and N9 protons of adenine have been calorimetrically determined as a function of temperature. The H values for proton dissociation of these groups, with pK values of 4.19 and 9.92, were found to be 5.1 and 9.1 kcal/mole, respectively, at 25°C, =0.025. The C
p
values for proton dissociation of these groups were estimated to be –11 and –17 cal/mole-deg. These results indicate that the large heat capacity changes observed during conformational transitions of polynucleotides are not the result of ionization of the bases. 相似文献
39.
A.?V.?Kuz’minEmail author V.?P.?Gorelov E.?G.?Vaganov I.?V.?Korzun V.?A.?Kazantsev T.?I.?Aksenova I.?V.?Khromushin 《Russian Journal of Electrochemistry》2005,41(5):544-549
Investigations of phase transitions in barium cerate are carried out by methods of dilatometry and differential scanning calorimetry. Thermal desorption of gases and temperature dependences of electroconduction in dry and humid air are studied. Barium cerate exhibits complex polymorphism, undergoing a number of structural conversions at 300– 1300 K. The peaks in the spectra of thermal desorption of CO2 and H2O correlate with variations in the crystal lattice. Structural changes in BaCeO3 affect activation energies for the carrier transport and the shares of partial conductivities.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 620–626.Original Russian Text Copyright © 2005 by Kuz’min, Gorelov, Vaganov, Korzun, Kazantsev, Aksenova, Khromushin. 相似文献
40.
The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t 1/2 ( the half life of crystallization) and the appropriate temperature variable. The parameters such as the activation energy (Ed) for transport, the equilibrium melting temperature (T_m~0),the nucleation parameter (ψ),themaximum crystallization temperature (T_(e, max)), and the kinetic crystallizability (G) for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed. 相似文献