scholarly journals MECHANISMS OF FORMATION AND STRUCTURE POLYMER SALTS OF DIMETHYLAMINOETHYL METHACRYLATE WITH HETEROCYCLIC COMPOUNDS

2021 ◽  
Vol 07 (04) ◽  
Author(s):  
UBAYDULLA ABIDJANOVICH SAFAEV ◽  
Keyword(s):  
Activation Energy ◽  
Mathematical Model ◽  
Process Parameters ◽  
Heterocyclic Compounds ◽  
Composition Analysis ◽  
Radical Process ◽  
Formal Kinetics ◽  
Mechanisms Of Formation ◽  
Pmr Spectra ◽  
Kinetics Of

The article presents the results of studies of the main regularities of the polymerization of quaternary monomeric salts of dimethylaminoethylmethacrylate with heterocyclic compounds - N-α-chloromethylbenzoxazolone, N-α-bromomethylmercaptobenzthiazolthione and N-α-chloromethylbenztriazole, determined experimentally the values ​​of the kinetic process parameters. The structure and composition of the newly synthesized monomers and polymers were studied using PMR spectra and elemental composition analysis. The processes of polymerization of monomeric salts based on DMA and heterocyclic compounds were studied, the main kinetic regularities of the reactions were established, and it was shown that the system under study obeys the basic laws of the radical process, which is confirmed by the compilation of a mathematical model of the formal kinetics of the reaction. A mathematical model of radical polymerization was compiled, on the basis of which the ordinal values ​​and activation energy of the reaction were determined and the results were obtained that were adequate with the experimental ones.

Vulcanization of Elastomers. 47. Vulcanization of Natural Rubber and Polybutadiene with Benzoyl Peroxide

1966 ◽  
Vol 39 (3) ◽  
pp. 768-784 ◽  
Author(s):  
Walter Scheele ◽  
Ernst Rohde
Keyword(s):  
Activation Energy ◽  
Benzoic Acid ◽  
Natural Rubber ◽  
Benzoyl Peroxide ◽  
Polymer Chains ◽  
Acid Yield ◽  
First Order ◽  
Formal Kinetics ◽  
Peroxide Decomposition ◽  
Kinetics Of

Abstract The present article reports experiments intended to elucidate the kinetics of benzoyl peroxide decompositions in natural rubber and polybutadiene, and of consequent reactions. Both in natural rubber and in polybutadiene and at all temperatures, peroxide decomposition is first order with respect to concentration as well as time. The decomposition rate is substantially higher in natural rubber than in polybutadiene, and independent of the constitution of the polymer chains of the polybutadiene (tacticity, vinyl side groups, and the like). A somewhat higher activation energy of peroxide decomposition was derived for polybutadiene than for natural rubber. Formation of benzoic acid and crosslinking both follow a first order time law; the rates for peroxide decomposition, formation of benzoic acid, and crosslinking are the same in natural rubber and polybutadiene. It seems probable that peroxide decomposition in polybutadiene is purely homolytic. Interaction between peroxide and natural rubber is assumed, resulting in an increase in the rate of decomposition. The benzoic acid yield is considerably higher in natural rubber than in polybutadiene, and diminishes in the latter with the increase in vinyl side groups. In natural rubber this yield is a function of temperature, but in polybutadiene it shows practically no temperature dependence. Benzoyloxy radicals are incorporated into the elastomers as benzoate groups, as confirmed by infrared spectroscopic determinations with cis-1,4 polybutadiene. An interpretation of the formal kinetics of the vulcanization of 1,5-polyenes is proposed, which, together with the experimental results, may be used as a basis for consideration of the reaction mechanism.

scholarly journals Development of a Mathematical Model for Kinetics of Obtaining Isocyanate via a Non-Phosgene Method for Example Benzylisocyanate

2020 ◽  
Vol 8 (4) ◽  
pp. 1491-1497
Keyword(s):  
Activation Energy ◽  
Mathematical Model ◽  
Kinetic Parameters ◽  
Kinetics Of

The paper considers theprocess of developing a mathematicalmodel for kineticsof obtainingisocyanates via a non-phosgene method non-catalytic thermolysis of carbamates. A mathematical model is presented, kinetic parameters such as activation energy and a pre—exponential multiplier are ascertained.

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

Effect of ionizing radiation on the kinetics of hydrogenation on the Ni-MgO mixed catalyst

1982 ◽  
Vol 47 (7) ◽  
pp. 1780-1786 ◽  
Author(s):  
Rostislav Kudláček ◽  
Jan Lokoč
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Liquid Phase ◽  
Ionizing Radiation ◽  
Oxide Catalyst ◽  
Absorbed Dose ◽  
Hydrogenation Rate ◽  
Solution Composition ◽  
Mixed Catalyst ◽  
Kinetics Of

The effect of gamma pre-irradiation of the mixed nickel-magnesium oxide catalyst on the kinetics of hydrogenation of maleic acid in the liquid phase has been studied. The changes of the hydrogenation rate are compared with the changes of the adsorbed amount of the acid and with the changes of the solution composition, activation energy, and absorbed dose of the ionizing radiation. From this comparison and from the interpretation of the experimental data it can be deduced that two types of centers can be distinguished on the surface of the catalyst under study, namely the sorption centres for the acid and hydrogen and the reaction centres.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

scholarly journals Fluoride Leaching of Titanium from Ti-Bearing Electric Furnace Slag in [NH4+]-[F−] Solution

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1176
Author(s):  
Fuqiang Zheng ◽  
Yufeng Guo ◽  
Feng Chen ◽  
Shuai Wang ◽  
Jinlai Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electric Furnace ◽  
Kinetic Equations ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Surface Chemical Reaction ◽  
Mechanism And Kinetics ◽  
Semi Empirical ◽  
Kinetics Of ◽  
Furnace Slag

The effects of F− concentration, leaching temperature, and time on the Ti leaching from Ti-bearing electric furnace slag (TEFS) by [NH4+]-[F−] solution leaching process was investigated to reveal the leaching mechanism and kinetics of titanium. The results indicated that the Ti leaching rate obviously increased with the increase of leaching temperature and F− concentration. The kinetic equation of Ti leaching was obtained, and the activation energy was 52.30 kJ/mol. The fitting results of kinetic equations and calculated values of activation energy both indicated that the leaching rate of TEFS was controlled by surface chemical reaction. The semi-empirical kinetics equation was consistent with the real experimental results, with a correlation coefficient (R2) of 0.996. The Ti leaching rate reached 92.83% after leaching at 90 °C for 20 min with F− concentration of 14 mol/L and [NH4+]/[F−] ratio of 0.4. The leaching rates of Si, Fe, V, Mn, and Cr were 94.03%, 7.24%, 5.36%, 4.54%, and 1.73%, respectively. The Ca, Mg, and Al elements were converted to (NH4)3AlF6 and CaMg2Al2F12 in the residue, which can transform into stable oxides and fluorides after pyro-hydrolyzing and calcinating.

scholarly journals A Study of the Impact of Graphite on the Kinetics of SPS in Nano- and Submicron WC-10%Co Powder Compositions

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 331-363
Author(s):  
Eugeniy Lantcev ◽  
Aleksey Nokhrin ◽  
Nataliya Malekhonova ◽  
Maksim Boldin ◽  
Vladimir Chuvil'deev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Continuous Heating ◽  
Diffusion Creep ◽  
Hard Alloys ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact ◽  
Kinetics Of

This study investigates the impact of carbon on the kinetics of the spark plasma sintering (SPS) of nano- and submicron powders WC-10wt.%Co. Carbon, in the form of graphite, was introduced into powders by mixing. The activation energy of solid-phase sintering was determined for the conditions of isothermal and continuous heating. It has been demonstrated that increasing the carbon content leads to a decrease in the fraction of η-phase particles and a shift of the shrinkage curve towards lower heating temperatures. It has been established that increasing the graphite content in nano- and submicron powders has no significant effect on the SPS activation energy for “mid-range” heating temperatures, QS(I). The value of QS(I) is close to the activation energy of grain-boundary diffusion in cobalt. It has been demonstrated that increasing the content of graphite leads to a significant decrease in the SPS activation energy, QS(II), for “higher-range” heating temperatures due to lower concentration of tungsten atoms in cobalt-based γ-phase. It has been established that the sintering kinetics of fine-grained WC-Co hard alloys is limited by the intensity of diffusion creep of cobalt (Coble creep).

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