Non-isothermal oxidation kinetics of single- and multi-walled carbon nanotubes up to 1273 K in ambient

Non-isothermal oxidation kinetics of single- and multi-walled carbon nanotubes (CNTs) have been studied using thermogravimetry up to 1273 K in ambient using multiple heating rates. One single heating rate based model-fitting technique and four multiple heating rates based model-free isoconversional...

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Bibliographic Details
Published in:Journal of thermal analysis and calorimetry 2012-03, Vol.107 (3), p.1093-1103
Main Authors: Sarkar, Soumya, Das, Probal Kr
Format: Article
Language:English
Subjects:
Analytical Chemistry
Chemistry
Chemistry and Materials Science
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Inorganic Chemistry
Materials science
Measurement Science and Instrumentation
Nanoscale materials and structures: fabrication and characterization
Nanotubes
Oxidation-reduction reaction
Physical Chemistry
Physics
Polymer Sciences
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Summary:Non-isothermal oxidation kinetics of single- and multi-walled carbon nanotubes (CNTs) have been studied using thermogravimetry up to 1273 K in ambient using multiple heating rates. One single heating rate based model-fitting technique and four multiple heating rates based model-free isoconversional methods were used for this purpose. Depending on nanotube structure and impurity content, average activation energy ( E a ), pre-exponential factor ( A ), reaction order ( n ), and degradation mechanism changed considerably. For multi-walled CNTs, E a and A evaluated using model-fitting technique were ranged from 142.31 to 178.19 kJ mol −1 , respectively, and from 1.71 × 10 5 to 5.81 × 10 7  s −1 , respectively, whereas, E a for single-walled CNTs ranged from 83.84 to 148.68 kJ mol −1 and A from 2.55 × 10 2 to 1.18 × 10 7  s −1 . Although, irrespective of CNT type, the model-fitting method resulted in a single kinetic triplet i.e., E a , A , and reaction mechanism, model-free isoconversional methods suggested that thermal oxidation of these nanotubes could be either a simple single-step mechanism with almost constant activation energy throughout the reaction span or a complex process involving multiple mechanisms that offered varying E a with extent of conversion. Criado method was employed to predict degradation mechanism(s) of these CNTs.
ISSN:1388-6150
1588-2926
1572-8943
DOI:10.1007/s10973-011-1797-x