Epoxy siloxane/ZnO quantum dot nanocomposites: Model-fitting and model-free approaches to kinetic analysis of non-isothermal curing process

2019 ◽  
Vol 135 ◽  
pp. 270-280 ◽  
Author(s):  
Fateme Asadi ◽  
Ali Jannesari ◽  
Amirmasoud Arabi
Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7564
Author(s):  
Haibo Wan ◽  
Zhen Huang

Thermal degradation of nylon-6 tennis string nylon wastes in inert nitrogen and air atmospheres was investigated by means of multiple heating-rate thermogravimetric analyses. The results obtained under the heating rates of 5–20 K/min are compared in terms of degradation feature and specific temperature for two atmospheres. Using nonisothermal data, kinetic analysis was thoroughly conducted using various isoconversional model-free methods, including Starink, Madhusudanan–Krishnan–Ninan, Tang, Coats–Redfern, and Flynn–Wall–Ozawa methods. With these kinetic analysis methods, the activation energy over the entire degradation process was successfully calculated. By means of the model-fitting master-plots method, the first-order chemical reaction model was determined to be the most appropriate mechanism function for describing pyrolysis and oxidative thermal degradation of nylon-6 waste. Using kinetic parameters, satisfactory matching against experimental data resulted using the Coats–Redfern method for both cases. Furthermore, thermodynamic parameters such as changes in entropy, enthalpy, and Gibbs free energy during thermal degradation processes were evaluated.


Fuel ◽  
2018 ◽  
Vol 214 ◽  
pp. 369-380 ◽  
Author(s):  
Imtiaz Ali ◽  
Salman Raza Naqvi ◽  
Ali Bahadar

2011 ◽  
Vol 523 (1-2) ◽  
pp. 63-69 ◽  
Author(s):  
Chao Zhang ◽  
Wieslaw K. Binienda ◽  
Liming Zeng ◽  
Xiaochuan Ye ◽  
Shuwen Chen

2019 ◽  
Vol 38 (2) ◽  
pp. 202-212 ◽  
Author(s):  
Ghulam Ali ◽  
Jan Nisar ◽  
Munawar Iqbal ◽  
Afzal Shah ◽  
Mazhar Abbas ◽  
...  

Due to a huge increase in polymer production, a tremendous increase in municipal solid waste is observed. Every year the existing landfills for disposal of waste polymers decrease and the effective recycling techniques for waste polymers are getting more and more important. In this work pyrolysis of waste polystyrene was performed in the presence of a laboratory synthesized copper oxide. The samples were pyrolyzed at different heating rates that is, 5°Cmin−1, 10°Cmin−1, 15°Cmin−1 and 20°Cmin−1 in a thermogravimetric analyzer in inert atmosphere using nitrogen. Thermogravimetric data were interpreted using various model fitting (Coats–Redfern) and model free methods (Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman). Thermodynamic parameters for the reaction were also determined. The activation energy calculated applying Coats–Redfern, Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman models were found in the ranges 105–148.48 kJmol−1, 99.41–140.52 kJmol−1, 103.67–149.15 kJmol−1 and 99.93–141.25 kJmol−1, respectively. The lowest activation energy for polystyrene degradation in the presence of copper oxide indicates the suitability of catalyst for the decomposition reaction to take place at lower temperature. Moreover, the obtained kinetics and thermodynamic parameters would be very helpful in determining the reaction mechanism of the solid waste in a real system.


CrystEngComm ◽  
2017 ◽  
Vol 19 (34) ◽  
pp. 4992-5000 ◽  
Author(s):  
C. Bartha ◽  
C. E. Secu ◽  
E. Matei ◽  
M. Secu

The crystallization mechanism of sol–gel-derived NaYF4:(Yb,Er) up-converting phosphors has been studied by differential scanning calorimetry analysis using both model-free and model fitting approaches.


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