scholarly journals Quantitative evaluation of the non-thermal effect in microwave induced polymer curing

RSC Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 3740-3750
Author(s):  
Kun Li ◽  
Tuo Ping ◽  
Haobo Zhang ◽  
Junying Zhang ◽  
Jue Cheng ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Effect ◽  
Quantitative Evaluation ◽  
Polymer Curing ◽  
Exponential Factors

The non-thermal effect of microwave was evaluated quantitatively by the calculation of activation energy and pre-exponential factors with an isothermal microwave.

Isotope Exchange of Gaseous Oxygen with Oxide LaMno3+δ Nanograins Boundary

2010 ◽  
Vol 297-301 ◽  
pp. 1301-1305
Author(s):  
Anatoly Yakovlevich Fishman ◽  
Tatiana Eugenievna Kurennykh ◽  
Vladimir Borisovich Vykhodets ◽  
V.B. Vykhodets
Keyword(s):  
Activation Energy ◽  
Exchange Rate ◽  
Isotope Exchange ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Gaseous Oxygen ◽  
Exponential Factor ◽  
Significant Difference ◽  
Exponential Factors ◽  
Arrhenius Expression

Isotope exchange of oxygen 18О2 with the boundary of nanograins of oxide LaMnO3+ obtained by the method of shock-wave loading was investigated in the temperature range of 400 – 500 °C. It was established that the temperature dependence of the isotope exchange rate is described by the Arrhenius expression, the activation energy and the pre-exponential factor being 1.67 eV and 1.8∙102 cm/s, respectively. Comparison with literature data has shown that for oxide LaMnO3+, a significant difference in activation energies and pre-exponential factors is observed for the isotope exchange rate with a ‘defect-free’ surface and the nanograin boundary. In case of the boundary, these parameters were higher: the activation energy about two times, and the pre-exponential factor, by almost 7 orders of magnitude.

scholarly journals Advanced Isoconversional Kinetic Analysis for the Elucidation of Complex Reaction Mechanisms: A New Method for the Identification of Rate-Limiting Steps

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1683 ◽  
Author(s):  
Nicolas Sbirrazzuoli
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Single Step ◽  
Thermoanalytical Techniques ◽  
Diffusion Controlled ◽  
Physical Transformation ◽  
Exponential Factors ◽  
Isoconversional Kinetic Analysis ◽  
The Individual ◽  
Rate Limiting

Two complex cure mechanisms were simulated. Isoconversional kinetic analysis was applied to the resulting data. The study highlighted correlations between the reaction rate, activation energy dependency, rate constants for the chemically controlled part of the reaction and the diffusion-controlled part, activation energy and pre-exponential factors of the individual steps and change in rate-limiting steps. It was shown how some parameters computed using Friedman’s method can help to identify change in the rate-limiting steps of the overall polymerization mechanism as measured by thermoanalytical techniques. It was concluded that the assumption of the validity of a single-step equation when restricted to a given α value holds for complex reactions. The method is not limited to chemical reactions, but can be applied to any complex chemical or physical transformation.

A Kinetic Study of Wetland Plant Suaeda salsa L. Pyrolysis Using Thermogravimetric Analyzer

2013 ◽  
Vol 848 ◽  
pp. 126-130
Author(s):  
Hua Xiao Yan ◽  
Hui Zhao ◽  
Qi Liu ◽  
Yan Xiang Ai ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Three Dimensional ◽  
Nitrogen Atmosphere ◽  
Suaeda Salsa ◽  
Good Prospect ◽  
Heating Rates ◽  
Thermogravimetric Analyzer ◽  
Exponential Factors ◽  
Pyrolysis Feedstock ◽  
Diffusion Function

The Suaeda salsa L. has been discovered to be a great potential as a new kind of renewable energy. The pyrolytic characteristics and kinetics of S. salsa were investigated at heating rates of 5, 10, 20, 30°C/min under nitrogen atmosphere respectively. The most probable mechanism function was deduced using Popescu method, which is a three-dimensional diffusion function (), and n=-2/3. Activation energy and pre-exponential factors were studied through the FWO, KAS and Popescu methods. The results showed that the activation energy increase as the pyrolysis process and three stages were observed in the TG-DTG curves of S.salsa. The results showed that S.salsa as a pyrolysis feedstock has a great potential and a good prospect in bio-oil production.

Calculation of The Diffusion Parameters in an Ordered Ni3Al-Alloy for A Relaxed Lattice

1998 ◽  
Vol 527 ◽  
Author(s):  
C. Schmidt ◽  
J.L. Bocquet
Keyword(s):  
Activation Energy ◽  
Gradient Algorithm ◽  
Al Alloy ◽  
Self Diffusion ◽  
Barrier Heights ◽  
Diffusion Parameters ◽  
Exponential Factors ◽  
Diffusion Mechanisms ◽  
Body Potential ◽  
Semi Empirical

ABSTRACTUsing atomistic computer simulations, we calculate the diffusion parameters of an Ll2-ordered Ni3Al-alloy. A conjugate gradient algorithm under constant zero pressure and a semi-empirical N-body potential are applied to evaluate potential barrier heights and pre-exponential factors. We focus our investigation on those diffusion mechanisms that have been proposed to account for the experimentally observed but theoretically still disputed fast self-diffusion of Al in Ni3Al: antisite bridge mechanisms and correlated six-jump cycles. Our results demonstrate that the most competitive jumps or jump sequences involve AlNJ-antistructure atoms which are shown to play a key role in the diffusion process by either actively or passively lowering the activation energy of migration.

Relationship between the cycloaddition activation energy and thermal effect in solutions

2003 ◽  
Vol 13 (6) ◽  
pp. 259-260 ◽  
Author(s):  
Vladimir G. Uryadov ◽  
Evgenii N. Ofitserov
Keyword(s):  
Activation Energy ◽  
Thermal Effect

Microwave non-thermal effect reduces ELISA timing to less than 5 minutes

RSC Advances ◽  
2016 ◽  
Vol 6 (25) ◽  
pp. 20850-20857 ◽  
Author(s):  
Rajesh Ahirwar ◽  
Swati Tanwar ◽  
Utpal Bora ◽  
Pradip Nahar
Keyword(s):  
Activation Energy ◽  
Thermal Effect ◽  
Catalytic Effect

Microwave-mediated ELISA, which occurs in less than 5 minutes, is due to a microwave non-thermal effect. We postulate that the microwave non-thermal effect is a microwave catalytic effect acting by lowering the activation energy of reactants.

scholarly journals A Kinetic Study on Combustible Coastal Debris Pyrolysis via Thermogravimetric Analysis

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 836 ◽  
Author(s):  
Eunhye Song ◽  
Daegi Kim ◽  
Cheol-Jin Jeong ◽  
Do-Yong Kim
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Initial Temperature ◽  
Reduction Rate ◽  
Fuel Production ◽  
Pyrolysis Characteristics ◽  
Pollution Problem ◽  
Activation Rate ◽  
Environmental Pollution Problem ◽  
Exponential Factors

Coastal debris has recently emerged as a serious environmental pollution problem. Coastal debris can be treated using pyrolysis because it consists mainly of combustible materials like plastics (e.g., polyethylene (PE), polypropylene (PP), nylon) and wood. In this study, the pyrolysis characteristics of coastal debris were fully utilized by applying their basic data to fuel production. The initial temperature increased from 330 °C to 380 °C for the nylon fishing net coastal debris sample, from 405.01 °C to 430.08 °C for the PE fishing net coastal debris sample, from 395.01 °C to 419.96 °C for the PP rope coastal debris sample, and from 114.95 °C to 115.02 °C for the wood (bamboo) coastal debris sample. The activation rate of the global activation energy and the pre-exponential factors rose with the increasing heating rate, complementing the reduction rate constant due to the larger growth of the exponential term due to the kinetic models used.

An Alternative Constitutive Equation for Superplasticity

2007 ◽  
Vol 539-543 ◽  
pp. 2865-2871
Author(s):  
Buddhisagar Naik
Keyword(s):  
Activation Energy ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Model Development ◽  
Grain Boundary Sliding ◽  
Dislocation Slip ◽  
Exponential Factors ◽  
Accommodation Process ◽  
Diffusional Flow ◽  
Predicted Values

Different models have been put forward to explain superplasticity. Most of the models predict the independency of activation energy (Q) on stress. Superplasticity is observed in region II of creep curve (logε Vs σ/E). The most commonly considered mechanism for superplastic flow involves Grain Boundary Sliding (GBS), and it is necessary for an accommodation process to accompany GBS. The accommodation process might be grain boundary migration, recrystalisation, diffusional flow or some dislocation slip process. But the Arrhenius type of equation given by Becker gives the dependency of activation energy on stress. Here in this work we have considered this equation and relation between Q and σ is found out using genetic algorithm. The present model development studies the parameter optimization, where parameters appearing in the stress and energy relationship equation e.g. relationship between Q(σ) and σ for the Q(σ) equation given in present work as well as pre-exponential factors are optimized with the objective function being the error minimization of model predicted values and experimental data of strain are available from open literature.

Interdiffusion Studies in the Co- Mo System

2010 ◽  
Vol 297-301 ◽  
pp. 462-466 ◽  
Author(s):  
V.D. Divya ◽  
U. Ramamurty ◽  
Aloke Paul
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Diffusion Coefficient ◽  
Turbine Blades ◽  
Jet Engine ◽  
Solid Solution Strengthening ◽  
Atomic Mechanism ◽  
Impurity Diffusion Coefficient ◽  
Exponential Factors ◽  
Solution Strengthening

Study of interdiffusion in the Co-Mo system is important to understand the performance of turbine blades in jet engine applications. Mo is added to superalloys to increase the solid solution strengthening and the creep resistance. In this study, the interdiffusion coefficient in the Co(Mo) solid solution and impurity diffusion coefficient of Mo in Co are determined. Further, the activation energy and pre-exponential factors are calculated, which provide an idea about the atomic mechanism of diffusion.

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