Thermodynamic properties of small amorphous and crystalline Silica particles at low temperatures

1999 ◽  
Vol 8 (1) ◽  
pp. 19-30 ◽  
Author(s):  
A. Nittke ◽  
P. Esquinazi ◽  
H.-C. Semmelhack ◽  
A.L. Burin ◽  
A.Z. Patashinskii
Keyword(s):  
Thermodynamic Properties ◽  
Low Temperatures ◽  
Silica Particles ◽  
Crystalline Silica

Magnetic and thermodynamic properties of EuS/SrS multilayers at low temperatures

1989 ◽  
Vol 77 (1) ◽  
pp. 25-32 ◽  
Author(s):  
J. Wosnitza ◽  
H. v. L�hneysen ◽  
U. Walz ◽  
W. Zinn
Keyword(s):  
Thermodynamic Properties ◽  
Low Temperatures

scholarly journals Molecular Dynamic Investigations on the Adhesion Behaviors of Asphalt Mastic–Aggregate Interface

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5061
Author(s):  
Wenyi Xu ◽  
Xin Qiu ◽  
Shanglin Xiao ◽  
Ganghua Hu ◽  
Feng Wang ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Molecular Dynamic ◽  
Interfacial Adhesion ◽  
Silica Particles ◽  
Work Of Adhesion ◽  
Electrostatic Energy ◽  
Adsorption Effect ◽  
Asphalt Mastic ◽  
Polar Components ◽  
Molecular Arrangement

The asphalt mastic–aggregate interface plays an essential role in determining the service performance of asphalt mixtures. The objective of this paper was to investigate the adhesion behaviors and mechanism between asphalt mastic and aggregate based on molecular dynamic (MD) simulations. First, the asphalt mastic model considering the actual mass ratio of filler to asphalt (F/A) condition was established and validated in terms of thermodynamic properties. Second, the molecular arrangement characteristics of polar components on the aggregate substrate were analyzed by radial distribution function (RDF), relative concentration (RC), and mean square displacement (MSD). Third, the interfacial adhesion ability between asphalt and aggregate was quantitively evaluated based on the work of adhesion. Finally, the coupling effect of moisture and temperature on interfacial adhesion behaviors was investigated to explore the adhesion failure characteristics of the asphalt–aggregate interface. The results demonstrate that the thermodynamic properties could be employed to validate the reliability of the asphalt mastic model. The self-aggregation degree of polar components in base asphalt could be significantly increased with the addition of silica particles, exhibiting a change of configuration from “parallel arrangement” into “stack distribution” due to the high polarity of silica particles. The polar components in asphalt mastic exhibit a more uniform distribution state and lower mobility capability than base asphalt owing to the adsorption effect of silica particles. Silica particles with amounts of residual charges could significantly increase the electrostatic energy of the asphalt mastic–aggregate interface, contributing to an improvement of the adhesion between asphalt mastic and aggregate. The increase of temperature enhances the work of adhesion of the asphalt mastic–aggregate interface, which is opposite to that of the base asphalt–aggregate interface. The asphalt mastic exhibits a greater sensitivity to interfacial moisture damage than base asphalt. The findings would provide insights into a better understanding on the micro adhesion mechanism of the asphalt mastic–aggregate interface.

Reaction model and thermodynamic properties between sulfur-containing active groups and oxygen during coal self-heating

2021 ◽  
Vol 99 (1) ◽  
pp. 31-42
Author(s):  
Xuyao Qi ◽  
Liangzhou Chen ◽  
Jie Tang ◽  
Haihui Xin ◽  
Zhongqiu Liang
Keyword(s):  
Thermodynamic Properties ◽  
Low Temperatures ◽  
Structural Parameters ◽  
Reaction Model ◽  
Main Reaction ◽  
Chain Reactions ◽  
Self Heating ◽  
Oxidation Stage ◽  
Chemistry Calculation ◽  
Sulfur Containing

To further study the mechanism of coal self-heating, the reaction sequences and thermodynamic properties between sulfur-containing groups and oxygen during coal self-heating were analyzed. The benzyl mercaptan and diphenyl sulfide were selected as typical sulfur-containing structures existing in coal. Their structural parameters, frontier orbital characteristics, and thermodynamic parameters were analyzed through quantum chemistry calculation and their detailed reaction sequences with oxygen were proposed. The results indicate that the thiol structure in coal can easily react with oxygen at low temperatures and release large amounts of heat (146.70 kJ/mol) during coal self-heating, providing active free radicals and energy for subsequent chain reactions of coal spontaneous combustion. The oxidation reaction between the thioether structure and oxygen cannot occur at room temperature. With the accumulation of heat, thioether gradually becomes active and reacts with oxygen to form sulfoxide and release an enormous amount of heat (248.09 kJ/mol), which can be further oxidized to sulfone with an increase in temperature. The reaction models of thiol and thioether groups during coal self-heating were proposed, which involves eight main reaction sequences (R1∼R8). It indicates that the reactions of thiol and thioether groups play crucial roles during the evolution of coal self-heating, with a slow oxidation stage at low temperatures and an accelerated oxidation stage at high temperatures.

Thermodynamic properties of erbium mono-and disilicide at low temperatures

2007 ◽  
Vol 46 (1-2) ◽  
pp. 72-76 ◽  
Author(s):  
N. P. Gorbachuk ◽  
S. N. Kirienko ◽  
V. R. Sidorko ◽  
I. M. Obushenko
Keyword(s):  
Thermodynamic Properties ◽  
Low Temperatures
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