Thermal stability and pyrolysis characteristics of MTMS aerogels prepared in pure water
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RESEARCH PAPER
Thermal stability and pyrolysis characteristics of MTMS aerogels prepared in pure water Zhi Li & Yan Zhang & Siqi Huang & Xiaoxu Wu & Long Shi & Qiong Liu
Received: 28 May 2020 / Accepted: 21 October 2020 # Springer Nature B.V. 2020
Abstract Silica aerogel (SA) is a nanoporous material and has attracted increasing attention in the field of thermal insulation in recent years. In this work, the thermal stability and pyrolysis characteristics of the methyltrimethoxysilane (MTMS) silica aerogel (MSA) prepared in pure water were investigated experimentally. The MSA shows a high thermal stability with the onset and peak temperature (Tonset and Tpeak) about 417 °C and 476 °C, respectively, in the pyrolysis process. The oxidation kinetics reveals that the pyrolysis of MSA can be divided into three stages with the average apparent activation energy (E) of each stage being 382.8 kJ/mol, 364.4 kJ/mol, and 328.9 kJ/mol, respectively. The pre-exponential factor (A) has the same tendency with the E. The TG-FTIR analysis demonstrates that the CO2 and H2O are the main volatiles during the pyrolysis process and all of them increase against the temperature. It is further observed that the production of CO2 presents a linear increase, and the H2O shows an obvious two-stage form along with the temperature. Compared with other hydrophobic SAs, Z. Li : Y. Zhang : S. Huang : X. Wu : Q. Liu (*) School of Resource and Safety Engineering, Central South University, Changsha 410083, People’s Republic of China e-mail: [email protected] X. Wu School of Economics and Management, Changsha University, Changsha 410083, People’s Republic of China L. Shi Civil and Infrastructure Engineering Discipline, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
the MSA has a larger Tonset and Tpeak and much larger E, indicating better thermal safety. The research outcomes provide a technical guide to analyze the thermal pyrolysis of hydrophobic SA and put a new insight to reduce their thermal hazards, which is beneficial to the development of higher-performance nanoporous silica aerogels for the thermal insulation field. Keywords MTMS aerogels . Thermal stability . Oxidation kinetic . Thermodynamic . Pyrolysis process . Thermal hazard
Introduction Silica aerogels (SA) as a well-recognized three-dimensional mesoporous (2–50 nm) material usually consist of more than 90% pores and less than 5% solid skeletons (Hüsing and Schubert 1998; Huang et al. 2020), which were initially prepared by Kistler in 1931 (Kistler 1931, 1932). This unique porous structure creates a low density, ultra-low thermal conductivity, and super-high specific surface area (Li et al. 2020), which enable the wide application of SA in thermal insulation areas, such as residential and industrial buildings (Cuce et al. 2014), industrial pipelines (Meador et al. 2009), electronic devices (Zhao et al. 2015), and spacecrafts (Randall et al. 2011). With the development of low-cost preparation technology (Huber et al. 2017; Koebel et al. 2016), the usage of S
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