Methyltrichlorosilane modified hydrophobic silica aerogels and their kinetic and thermodynamic behaviors: Graphical Abstract

Zhang, W, Li, Z, Shi, L, Li, Z, Luo, Y, Liu, Q and Huang, R 2019, 'Methyltrichlorosilane modified hydrophobic silica aerogels and their kinetic and thermodynamic behaviors: Graphical Abstract', Journal of Sol-Gel Science and Technology, vol. 89, no. 2, pp. 448-457.


Document type: Journal Article
Collection: Journal Articles

Title Methyltrichlorosilane modified hydrophobic silica aerogels and their kinetic and thermodynamic behaviors: Graphical Abstract
Author(s) Zhang, W
Li, Z
Shi, L
Li, Z
Luo, Y
Liu, Q
Huang, R
Year 2019
Journal name Journal of Sol-Gel Science and Technology
Volume number 89
Issue number 2
Start page 448
End page 457
Total pages 10
Publisher Springer New York LLC
Abstract To reduce the flammability, hydrophobic silica aerogels (SAs) were modified by replacing commonly used trimethylchlorosilane (TMCS) with methyltrichlorosilane (MTCS). It was observed that the MTCS modified SAs (MSA) showed similar physicochemical properties to those TMCS modified SAs (TSA), including the density, thermal conductivity, hydrophobicity, and even thermal stability. However, the flammability of MSA was observed much lower than that of TSA, which was reflected by the significantly decreased gross calorific value (GCV). Furthermore, it was known from the kinetic and thermodynamic analyses that the pyrolysis of MSA became more difficult with the increasing conversion rate (α), which was evidenced by the fact that the apparent activation energy (E) kept rising to about 194 kJ/mol during the whole pyrolysis. Based on the changed E along the time, the pyrolysis process could be divided into two stages, in which α = 0.4 was considered as the turning point. Those main thermodynamic parameters, including pre-exponential factor (A) and the changes of enthalpy (ΔH) and entropy (ΔS), showed a quite consistent tendency with the E, whereas the change of Gibbs free energy (ΔG) almost kept unchanged. The research outcome of this study can provide a deep understanding of the pyrolysis process of SAs and render the public realize the thermal hazard risk of SAs.
Subject Construction Materials
Keyword(s) Kinetics
Methyltrichlorosilanes
Silica aerogels
Thermal conductivity
Thermodynamics
Thermostability
DOI - identifier 10.1007/s10971-018-4882-9
Copyright notice © Springer Science+Business Media, LLC, part of Springer Nature 2018
ISSN 0928-0707
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