scholarly journals Differential Scanning Calorimetry of Metamict Pu-Substituted Zirconolite

1982 ◽  
Vol 15 ◽  
Author(s):  
Dean E. Peterson ◽  
Frank W. Clinard
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Total Energy ◽  
Temperature Dependence ◽  
Radiation Damage ◽  
Rate Constant ◽  
Stored Energy ◽  
Scanning Calorimetry ◽  
No Release

ABSTRACTSamples of CaPuTi2O7 were prepared by cold pressing and sintering. Plutonium was substituted for zirconium in order to characterize radiation damage effects. The energy stored in a sample which had reached saturation in swelling after storage at ambient temperature was measured with a differential scanning calorimeter. The total energy of 6.6±0.1 cal/g is released over the range 485–715° C. The activation energy of annealing of the damage is 1.22±0.05 eV. The temperature dependence of the rate constant is described by kT= 5.96E4 exp(−1.22/kBT) s−1 where kB and T are the Boltzmann's constant and temperature(K) respectively. A sample stored at 600°C was similarly evaluated and showed no release of stored energy to the precision of the apparatus (±0.1 cal/g). These results are applied to analysis of waste incorporation in Synroc and are correlated with analogous parameters for other materials.

Equal channel angular pressing processing routes and associated structure modification: a differential scanning calorimetry and X-ray line profile analysis

2012 ◽  
Vol 27 (3) ◽  
pp. 194-199 ◽  
Author(s):  
A. Sarkar ◽  
Satyam Suwas ◽  
D. Goran ◽  
J.-J. Fundenberger ◽  
L.S. Toth ◽  
...  
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Equal Channel Angular Pressing ◽  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Stored Energy ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Angular Pressing

The effectiveness of different routes of equal channel angular pressing (A, Bc, and C) is studied for commercially pure copper. The stored energy and the activation energy of recrystallization for the deformed samples were quantified using differential scanning calorimetry and X-ray diffraction line profile analysis. Results of the study revealed that the dislocation density and the stored energy are higher in the case of route Bc deformed sample. The activation energy for recrystallization is lower for route Bc.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

scholarly journals Brazilian gutta-percha points. Part II: thermal properties

2007 ◽  
Vol 21 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Cláudio Maniglia-Ferreira ◽  
Eduardo Diogo Gurgel-Filho ◽  
João Batista Araújo Silva Jr ◽  
Regina Célia Monteiro de Paula ◽  
Judith Pessoa Andrade Feitosa ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Physical Properties ◽  
Ambient Temperature ◽  
Amorphous Phase ◽  
Thermal Behaviour ◽  
Chemical Structure ◽  
Scanning Calorimetry ◽  
Gutta Percha ◽  
Thermal Manipulation

This study was undertaken to explore the effect of heating on gutta-percha, analyzing the occurrence of endothermic peaks corresponding to the transformation that occurs in the crystalline structure of the polymer during thermal manipulation. This study also seeked to determine the temperature at which these peaks occur, causing a transformation from the beta- to the alpha-form, and from the alpha- to the amorphous phase. Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP, Dentsply FM) and pure gutta-percha (control) were analysed using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The transition temperatures were determined and analysed. With the exception of Dentsply 0.04 and Dentsply 0.06, the majority of the products showed thermal behaviour typical of beta-gutta-percha, with two endothermic peaks, exhibiting two crystalline transformations upon heating from ambient temperature to 130°. Upon cooling and reheating, few samples presented two endothermic peaks. It was concluded that heating dental gutta-percha to 130°C causes changes to its chemical structure which permanently alter its physical properties.

Study on Curing Kinetics of MEP-15/593/660 System

2014 ◽  
Vol 988 ◽  
pp. 31-35
Author(s):  
Jia Le Song ◽  
Chan Chan Li ◽  
Zhi Mi Zhou ◽  
Chao Qiang Ye ◽  
Wei Guang Li
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Kinetic Parameters ◽  
Curing Kinetics ◽  
Conversion Ratio ◽  
Scanning Calorimetry ◽  
Degree Of Cure ◽  
Curing Kinetic ◽  
The Relationship ◽  
Kinetics Of

Curing kinetics of MEP-15/593 system and MEP-15/593/660 system is studied by means of differential scanning calorimetry (DSC). Curing kinetic parameters are evaluated and the relationship between diluent 660 and the curing properties is investigated. The results show that the diluent 660 can not only reduce viscosity and activation energy, but also improve the degree of cure and conversion ratio.

Study on the Melting Mechanism of Maleic Anhydride

2020 ◽  
Vol 10 (1) ◽  
pp. 65-78
Author(s):  
Bratati Das ◽  
Ashis Bhattacharjee
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Maleic Anhydride ◽  
Temperature Dependence ◽  
Growth Models ◽  
Melting Process ◽  
Nucleation And Growth ◽  
Crystalline Solid ◽  
Scanning Calorimetry ◽  
Melting Mechanism

Background: Melting of a pure crystalline material is generally treated thermodynamically which disregards the dynamic aspects of the melting process. According to the kinetic phenomenon, any process should be characterized by activation energy and preexponential factor where these kinetic parameters are derivable from the temperature dependence of the process rate. Study on such dependence in case of melting of a pure crystalline solid gives rise to a challenge as such melting occurs at a particular temperature only. The temperature region of melting of pure crystalline solid cannot be extended beyond this temperature making it difficult to explore the temperature dependence of the melting rate and consequently the derivation of the related kinetic parameters. Objective: The present study aims to explore the mechanism of the melting process of maleic anhydride in the framework of phase transition models. Taking this process as just another first-order phase transition, occurring through the formation of nuclei of new phase and their growth, particular focus is on the nucleation and growth models. Methods: Non-isothermal thermogravimetry, as well as differential scanning calorimetry studies, has been performed. Using isoconversional kinetic analysis, temperature dependence of the activation energy of melting has been obtained. Nucleation and growth models have been utilized to obtain the theoretical temperature dependencies for the activation energy of melting and these dependencies are then compared with the experimentally estimated ones. Conclusion: The thermogravimetry study indicates that melting is followed by concomitant evaporation, whereas the differential scanning calorimetry study shows that the two processes appear in two different temperature regions, and these differences observed may be due to the applied experimental conditions. From the statistical analysis, the growth model seems more suitable than the nucleation model for the interpretation of the melting mechanism of the maleic anhydride crystals.

DEA and DSC study of cubic silsesquioxane epoxy resin nanocomposites

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Newton Luiz Dias Filho ◽  
Hermes Adolfo de Aquino
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Fracture Toughness ◽  
Differential Scanning Calorimetry ◽  
Epoxy Resin ◽  
Loss Factor ◽  
Tensile Modulus ◽  
Dielectric Analysis ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry

AbstractNon-isothermal dielectric analysis (DEA) and differential scanning calorimetry (DSC) techniques were used to study the epoxy nanocomposites prepared by reacting 1,3,5,7,9,11,13,15-octa[dimethylsiloxypropylglycidylether] pentaciclo [9.5.1.13,9.15,15 .17,13] octasilsesquioxane (ODPG) with methylenedianiline (MDA). Loss factor (ε”) and activation energy were calculated by DEA. The relationships between the loss factor, the activation energy, the structure of the network, and the mechanical properties were investigated. Activation energies determined by DEA and DSC, heat of polymerization, fracture toughness and tensile modulus show the same profile for mechanical properties with respect to ODPG content.

Thermal annealing of natural, radiation-damaged pyrochlore

2017 ◽  
Vol 232 (1-3) ◽  
Author(s):  
Peter Zietlow ◽  
Tobias Beirau ◽  
Boriana Mihailova ◽  
Lee A. Groat ◽  
Thomas Chudy ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Scattering ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Powder Diffraction ◽  
Scanning Calorimetry ◽  
Natural Radiation ◽  
Α Decay ◽  
X Ray ◽  
Decay Products

AbstractRadiation damage in minerals is caused by the α-decay of incorporated radionuclides, such as U and Th and their decay products. The effect of thermal annealing (400–1000 K) on radiation-damaged pyrochlores has been investigated by Raman scattering, X-ray powder diffraction (XRD), and combined differential scanning calorimetry/thermogravimetry (DSC/TG). The analysis of three natural radiation-damaged pyrochlore samples from Miass/Russia [6.4 wt% Th, 23.1·10

Heat Capacity and Thermodynamic Properties of LaBr3 at 300 – 1100 K

2004 ◽  
Vol 59 (11) ◽  
pp. 825-828
Author(s):  
L. Rycerz ◽  
E. Ingier-Stocka ◽  
B. Ziolek ◽  
S. Gadzuric ◽  
M. Gaune-Escard
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Temperature Dependence ◽  
Enthalpy Of Formation ◽  
Thermodynamic Functions ◽  
Molar Enthalpy ◽  
Standard Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Temperature Range

The heat capacity of solid and liquid LaBr3 was measured by Differential Scanning Calorimetry (DSC) in the temperature range 300 - 1100 K. The obtained results were fitted by a polynomial temperature dependence. The enthalpy of fusion of LaBr3 was also measured. By combination of these results with the literature data on the entropy, S0m (LaBr3, s, 298.15 K) and the standard molar enthalpy of formation, ΔformH0m (LaBr3, s, 298.15 K), the thermodynamic functions of lanthanum tribromide were calculated up to 1300 K

Study on the β1→α+β2 Transformation Kinetics of Ti-6Al-4V Alloy by DSC

2014 ◽  
Vol 508 ◽  
pp. 110-113
Author(s):  
Rong Hua Zhang ◽  
Biao Wu ◽  
Xiao Ping Zheng
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Phase Transformation ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Avrami Exponent ◽  
Transformation Kinetics ◽  
Cooling Process ◽  
Scanning Calorimetry ◽  
Kinetics Of

The temperature and duration of β1→α+β2 transformation of Ti-6Al-4V alloy in cooling process were measured by differential scanning calorimetry, and transformation activation energy and Avrami exponent of β1→α+β2 were also calculated. The results show that the cooling rate is in the range of 在5～20°C/min, the transformation temperature and the transformation duration β1→α+β2 transformation of Ti-6Al-4V alloy decreased with the increasing cooling rate, its transformation activation energy decreased with the increasing phase transformation volume fraction, and Avrami exponent was between 1 and 2 at 660°C.

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