Thermal stability and kinetics of formation of Mg3(OH)5Cl·4 H2O

2020 ◽  
Author(s):  
Adéla Jiříčková ◽  
Michal Lojka ◽  
Anna-Marie Lauermannová ◽  
Milena Pavlíková ◽  
Zbyšek Pavlík ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Kinetics Of Formation ◽  
Kinetics Of

scholarly journals Thermal Stability and Kinetics of Formation of Magnesium Oxychloride Phase 3Mg(OH)2∙MgCl2∙8H2O

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 767 ◽  
Author(s):  
Michal Lojka ◽  
Ondřej Jankovský ◽  
Adéla Jiříčková ◽  
Anna-Marie Lauermannová ◽  
Filip Antončík ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Construction Materials ◽  
Simultaneous Thermal Analysis ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Sustainable Building ◽  
X Ray ◽  
Kinetics Of Formation ◽  
Magnesium Oxychloride ◽  
Kinetics Of

In this paper, magnesium oxychloride cement with stoichiometry 3Mg(OH)2∙MgCl2∙8H2O (MOC 3-1-8) was prepared and characterized. The phase composition and kinetics of formation were studied by X-ray diffraction (XRD) and Rietveld analysis of obtained diffractograms. The chemical composition was analyzed using X-ray fluorescence (XRF) and energy dispersive spectroscopy (EDS). Furthermore, scanning electron microscopy (SEM) was used to study morphology, and Fourier Transform Infrared (FT-IR) spectroscopy was also used for the analysis of the prepared sample. In addition, thermal stability was tested using simultaneous thermal analysis (STA) combined with mass spectroscopy (MS). The obtained data gave evidence of the fast formation of MOC 3-1-8, which started to precipitate rapidly. As the length of the time of ripening increased, the amount of MgO decreased, while the amount of MOC 3-1-8 increased. The fast formation of the MOC 3-1-8 phase at an ambient temperature is important for its application in the production of low-energy construction materials, which corresponds with the challenges of a sustainable building industry.

Chemical Reactions between Thiocarbamylsulfenamides and Benzothiazylsulfenamides Leading to Cure Synergism

1977 ◽  
Vol 50 (4) ◽  
pp. 671-677 ◽  
Author(s):  
J. F. Krymowski ◽  
R. D. Taylor
Keyword(s):  
Thermal Stability ◽  
Chemical Reactions ◽  
Ionic Species ◽  
High Thermal Stability ◽  
High Cure ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Thermal Stability Of

Abstract A combination of N-oxydiethylenethiocarbamyl-N′-oxydiethylenesulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, and sulfur was found to be synergistic in acceleration of vulcanization. The combination reacts at 142°C to form a number of new covalent compounds, most of which eventually decompose to ionic species. The types of compounds produced and the kinetics of formation of these intermediate compounds explain the good scorch delay, high cure efficiency, and high thermal stability of the vulcanizates when combinations of these two sulfenamides are used as vulcanization accelerators.

Stabilization of lead lithium iron tungstate with adding barium titanate

1997 ◽  
Vol 12 (1) ◽  
pp. 13-16
Author(s):  
Chung-Hsin Lu ◽  
Buh-Kuan Fang
Keyword(s):  
Thermal Stability ◽  
Barium Titanate ◽  
Dielectric Permittivity ◽  
Perovskite Phase ◽  
Dielectric Constants ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Complete Formation ◽  
Thermal Stability Of ◽  
Formation Phase

The kinetics of formation, phase stabilities, and dielectric constants of Pb(Li1/4Fe1/4W1/2)O3 and BaTiO3-added Pb(Li1/4Fe1/4W1/2)O3 have been compared. The addition of 2 mol% BaTiO3 in Pb(Li1/4Fe1/4W1/2)O3 was confirmed to promote the complete formation of the perovskite phase at 700 °C. Also, the thermal stability of the perovskite phase was significantly enhanced, which resulted in an increase of the dielectric permittivity.

scholarly journals Kinetics of formation and thermal stability of Mg2(OH)3Cl·4H2O

2019 ◽  
Author(s):  
Michal Lojka ◽  
Adéla Jiříčková ◽  
Anna-Marie Lauermannová ◽  
Milena Pavlíková ◽  
Zbyšek Pavlík ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Kinetics Of Formation ◽  
Kinetics Of ◽  
Thermal Stability Of

Neutral and Negatively Charged Phosphate Modifications Altering Thermal Stability, Kinetics of Formation and Monovalent Ion Dependence of DNA G‐Quadruplexes

2019 ◽  
Vol 14 (8) ◽  
pp. 1212-1220 ◽  
Author(s):  
Yongdong Su ◽  
Hirofumi Fujii ◽  
Ekaterina A. Burakova ◽  
Boris P. Chelobanov ◽  
Masayuki Fujii ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Kinetics Of Formation ◽  
Monovalent Ion ◽  
Stability Kinetics ◽  
Kinetics Of

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

scholarly journals Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1597
Author(s):  
Iman Jafari ◽  
Mohamadreza Shakiba ◽  
Fatemeh Khosravi ◽  
Seeram Ramakrishna ◽  
Ehsan Abasi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Thermal Degradation ◽  
High Molecular Weight ◽  
Degradation Kinetics ◽  
Graphene Nanosheets ◽  
Thermal Degradation Kinetics ◽  
Graphene Nanocomposites ◽  
Kinetics Of ◽  
Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

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