title: Flammability and oxidation kinetics of hydrophobic silica aerogels.
abstract: Silica aerogels (SAs) present great application prospects especially on thermal insulation, but their flammability is usually ignored. A combined study on the combustion behaviors and oxidation kinetics of hydrophobic silica aerogels prepared by ambient pressure drying (SA-apd) and supercritical drying (SA-sd) was performed by employing cone calorimeter and thermal analysis. The whole combustion process for SAs could be divided into three stages in which a fire propagation phenomenon was observed with the radial propagation velocity of 6.6-8.3cms-1. Current investigations forcefully demonstrated that hydrophobic SAs were combustible and easy to flashover when exposed to a heat flux higher than 25kWm-2. Compared between the two SAs, the SA-sd owned a less fire risk with presenting a less fire hazard and a lower smoke toxicity than those of SA-apd. The oxidation kinetics by Ozawa-Flynn-Wall method revealed that SA-sd had larger apparent activation energies than those of SA-apd which conformed to the thermal stability analysis by TG-DSC. Furthermore, a two-step combustion mechanism was proposed to explain the combustion behaviors of SAs.
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China.
authors: Zhi
authors: Z
authors: Li
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China. Electronic address: chengxd@ustc.edu.cn.
authors: Xudong
authors: X
authors: Cheng
authors: Civil and Infrastructure Engineering Discipline, School of Engineering, RMIT University, GPO Box 2476, Melbourne VIC 3001, Australia.
authors: Long
authors: L
authors: Shi
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China.
authors: Song
authors: S
authors: He
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China.
authors: Lunlun
authors: L
authors: Gong
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China.
authors: Congcong
authors: C
authors: Li
authors: State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027, P. R. China. Electronic address: zhanghp@ustc.edu.cn.
authors: Heping
authors: H
authors: Zhang
keywords: Fire hazard; Flammability; Hydrophobic silica aerogel; Oxidation kinetics; Thermal decomposition