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1.
We investigated the features of the glass transition relaxation of two room temperature ionic liquids using DSC. An important
observation was that the heat capacity jump, that is the signature of the glass transition relaxation, shows a particularly
strong value in this type of new and promising materials, candidates for a range of applications. This suggests a high degree
of molecular mobility in the supercooled liquid state. The study of the influence of the heating rate on the temperature location
of the glass transition signal, allowed the determination of the activation energy at the glass transition temperature, and
the calculation of the fragility index of these two ionic glass-formers. It was concluded that this kind of materials belong
to the class of relatively strong glass-forming systems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
The
reaction of ilmenite titanium raw material with sulphuric acid was investigated
in ‘hazard’ type calorimetric system. The investigations show
the essential influence of initial temperature, particle size distribution
and concentration of sulphuric acid on rate and heat power of reaction and
determine the limits of safety of the process and also its efficiency. 相似文献
3.
A. Przepiera M. Jablonski M. Wisniewski 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1341-1345
The reaction of ilmenite titanium raw materials with sulphuric acid has been studied in a non-isothermal-non-adiabatic type calorimeter. The influence of different starting conditions, temperature and ilmenite particle-size distribution on the thermo-kinetics of the reaction was investigated. A kinetic model is presented for this heterogeneous system for a specified ilmenite particle-size distribution and starting temperature. On the basis of this model and experimentally determined parameters it it possible to analyse by simulation the autothermic reaction of digestion of different titanium ores with sulphuric acid. 相似文献
4.
H. Ratajska A. Przepiera M. Wišniewski 《Journal of Thermal Analysis and Calorimetry》1990,36(6):2131-2134
During heating hydrous titanium dioxide with a general empirical formula TiO2·xH
2O·ySO
3 prepared by hydrolysis of titanium sulphate solution drying, dehydration, desulphurization and anatase — rutile transformation proceed. The studies applying the DTA, TG, DTG methods have been carried out. To separate the particular effects damp samples, dried up to constant mass samples as well as samples after removing sulphur compounds have been used.
Zusammenfassung Während des Erhitzens von wasserhaltigem Titandioxid der allgemeinen Formel TiO2 ·xH2O ·ySO3, hergestellt durch Hydrolyse von Titansulfatlösung, verlaufen Trocknung, Dehydratation, Desulfurisation und eine Anatas — Rutil Umwandlung. Die Untersuchungen wurden unter Anwendung von DTA, TG und DTG durchgeführt. Zur Unterscheidung der einzelnen Effekte wurden feuchte, bis zur Massekonstantheit getrocknete als auch entschwefelte Proben verwendet.相似文献
5.
K Borowiec A. Przepiera K. Kolbrecka 《Journal of Thermal Analysis and Calorimetry》1991,37(3):637-644
The intrinsic kinetics, unaffected by diffusional and mass transfer effects, of the air oxidation of Na2TiF6 and Na3TiF6 were determined by using a nonisothermal technique. The oxidation of these sodium fluorotitanates proceeds through two-step reactions involving the formation of oxyfluorotitanate, i.e. Na3TiOF5, as the intermediate. The oxidation rate shows a first-order dependence on the amount of the unreacted solids for each of the two-step reactions for both fluorotitanates. The activation energy for the further oxidation of Na3TiOF5 to a mixture of NaF + TiO2 was determined to be 52.4 kJ/mol and 55.3 kJ/raol for Na2TiF6 and Na3TiF6 as reactants, respectively. 相似文献
6.
The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations
were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples
were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of
hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the
best fitting experimental data.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
A. Przepiera M. Jablonski M. Wišniewski 《Journal of Thermal Analysis and Calorimetry》1990,36(6):2135-2138
A direct method of evaluating of kinetic equation parameters based on TG curve is proposed. The method was applied to calculate kinetic parameters of the process of dehydration of hydrous titanium dioxide.
Zusammenfassung Es wird ein direktes Verfahren zur Bestimmung der Parameter der kinetischen Gleichung auf der Basis von TG-Kurven gegeben. Das Verfahren wurde zur Berechnung der kinetischen Parameter des Dehydratationsprozesses von wasserhaltigem Titandioxid benutzt.相似文献
8.
Jolanta Wolska Krystyna Przepiera Hanna Grabowska Aleksander Przepiera Maciej Jabłoński Roman Klimkiewicz 《Research on Chemical Intermediates》2008,34(1):43-51
This paper reports the investigation ofC-alkylation of phenol with methanol over zinc ferrite as a catalyst. The reactions were carried out in gas phase at atmospheric
pressure in dependence of increasing temperature. The total selectivity towardsortho-cresol and 2,6-xylenol over 300°C surpassed 90%. ZnFe2O4 was obtained by oxidative precipitation method from solution of iron (II) sulphate and zinc sulphate at 60°C. Based on the
results, the best equation describing the oxidation reaction rate was found. The obtained products have been investigated
using X-ray fluorescence spectrometry and X-ray diffraction analysis. 相似文献
9.
Titanium raw materials play important role as a source of titanium and titanium dioxide. The investigation of the rate of
oxidation and phase transformation of titanium slag in static air atmosphere by use of thermogravimetry (TG) and X-ray diffractometry
(XRD) were presented. The investigation were carried out for three different particle size fractions to determine influence
of this parameter on rate of reaction. To estimate kinetic parameters was used the kinetic model of contracting volume. The
value of kinetic parameters show that influence of heating rate and particle size on rate of reaction is not so large. The
thermogravimetric investigations of the oxidation of titanium slag in air atmosphere shown that reaction proceeds in two stages.
The XRD investigation shown that titanium slag has the pseudobrookite structure and its diffraction pattern is very close
to the diffractogram of magnesium titanate MgTi2O5 and iron magnesium titanium oxide (Fe-Mg-Ti-O). At elevated temperature the structure of slag transforms to the ferric pseudobrookite
structure and excess titanium dioxide forms the rutile phase.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
The aim of the present study was to determine the kinetic equations for the thermal transformations of precipitated iron oxides
and hydroxides, namely for the process of thermal dehydroxylation of goethite and consecutive of hematite crystal structure
growth as well as for the oxidation of magnetite to maghemite and its thermal transformation into crystalline hematite. The
investigations have been carried out using thermogravimetry (TG/DTG/DTA), X-ray powder diffractometry (XRD) and high temperature
powder diffractometry (HT-XRD). This presentation contains the continuation of our earlier works.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献