Evaluation of realistic 95% confidence intervals for the activation energy calculated by the iterative linear integral isoconversional method

2011 ◽  
Vol 66 (12) ◽  
pp. 2879-2882 ◽  
Author(s):  
Junmeng Cai ◽  
Dong Han ◽  
Yong Chen ◽  
Siyu Chen
Keyword(s):  
Activation Energy ◽  
Confidence Intervals ◽  
Isoconversional Method ◽  
Linear Integral

Evaluation of activation energy of epoxy resin grafted with polyurethane using modified non-linear integral isoconversional method

2014 ◽  
Vol 18 (sup4) ◽  
pp. S4-466-S4-472
Author(s):  
Z. J. Song ◽  
J. L. Xie ◽  
Q. Lin ◽  
Z. H. Cao ◽  
X. L. Weng ◽  
...  
Keyword(s):  
Activation Energy ◽  
Epoxy Resin ◽  
Isoconversional Method ◽  
Non Linear ◽  
Linear Integral

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

Confidence intervals for the activation energy estimated by few experiments

1997 ◽  
Vol 355 (2-3) ◽  
pp. 175-180 ◽  
Author(s):  
Sergey Vyazovkin ◽  
Nicolas Sbirrazzuoli
Keyword(s):  
Activation Energy ◽  
Confidence Intervals

Influence of carbon nanofillers on the curing kinetics of epoxy-amine resin

RSC Advances ◽  
2015 ◽  
Vol 5 (110) ◽  
pp. 90437-90450 ◽  
Author(s):  
L. Vertuccio ◽  
S. Russo ◽  
M. Raimondo ◽  
K. Lafdi ◽  
L. Guadagno
Keyword(s):  
Activation Energy ◽  
Curing Kinetics ◽  
Isoconversional Method ◽  
Epoxy Amine ◽  
Carbon Nanofillers ◽  
Advanced Isoconversional Method ◽  
Kinetics Of

Variation of the activation energy with conversion obtained by “advanced isoconversional method”.

scholarly journals Effect of components on the curing of glycidyl azide polymer spherical propellant through rheological method

2018 ◽  
Vol 5 (10) ◽  
pp. 181282 ◽  
Author(s):  
Liming He ◽  
Wei He ◽  
Zhongliang Ma
Keyword(s):  
Activation Energy ◽  
Model Fitting ◽  
Curing Kinetics ◽  
Isoconversional Method ◽  
Mechanical Analysis ◽  
Glycidyl Azide Polymer ◽  
Rheological Method ◽  
Cross Links ◽  
Gap Spherical Propellant ◽  
Glycidyl Azide

We have conducted a novel study of the influence of energy components (RDX, AP and CL-20) on curing kinetics of glycidyl azide polymer (GAP) spherical propellant based on rheological method. The autocatalytic model was used to describe curing kinetics and the parameters were determined by the model-fitting method. It was found that the incorporation of components hinders the cross-linking reaction of GAP spherical propellant. Integral isoconversional method was used on rheological kinetics to investigate the changes of the activation energy and we confirmed that the incorporation of components increased the activation energy. It was also found that such components had no effect on the trend of activation energy curves but shrank the peak value at a = 0.2. Dynamic mechanical analysis (DMA) showed the differences between pure curing system and its components. These findings are potentially helpful to control the curing effectively and optimize the processing schedules. The addition of components decreased α translation temperature which means the reduction in cross-links. The differences in the values of loss factor tan δ and β translation showed that pure curing system has lower resistance for side chain to motion.

A new diagnostic when determining the activation energy by the advanced isoconversional method

2016 ◽  
Vol 636 ◽  
pp. 85-93 ◽  
Author(s):  
James S. Campbell ◽  
John R. Grace ◽  
C. Jim Lim ◽  
David W. Mochulski
Keyword(s):  
Activation Energy ◽  
Isoconversional Method ◽  
Advanced Isoconversional Method

scholarly journals Thermal Decomposition of Brominated Butyl Rubber

2021 ◽  
Author(s):  
Wei Zhang ◽  
Jinping Xiong ◽  
Yang Zang ◽  
Yanli Lu ◽  
Weisheng Lin ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Isoconversional Method ◽  
Butyl Rubber ◽  
Heating Rates ◽  
Excellent Thermal Stability ◽  
Small Peak ◽  
Air Atmosphere ◽  
Brominated Butyl Rubber ◽  
Derivative Thermogravimetry

The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31–228.13 kJ·mol-1 at various heating rates. The non-isothermal degradation was found to be a first order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggested that brominated butyl rubber had excellent thermal stability. This study will indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.

Sign in / Sign up

Export Citation Format

Share Document