Preparation and flame-retardant properties of Al2O3-SiO2/cellulose composite aerogel
To address the issues such as inadequate thermal insulation performance and the combustible nature of the cellulose aerogel,the liquid nitrogen directional freezing and vacuum freeze-drying technology were utilized.Using microcrystalline cellulose as low-cost and eco-friendly raw material,while Al2O3-SiO2 sol as the chosen flame retardant and deionized water as the solvent,the co-hydrolysis process was modulated by adding boric acid as the catalyst.Al2O3-SiO2/cellulose aerogel was prepared with excellent heat insulation and flame retardant properties.To assess the impact of the solubility of Al2O3-SiO2 on the structure and properties of the composite aerogel,techniques such as scanning electron microscopy,Fourier transform infrared spectroscopy,thermogravimetric analysis,and cone calorimetry were used.Additionally,a comprehensive analysis of the flame retardant mechanism of the composite aerogel was conducted.The results show that with the increase of Al2O3-SiO2 sol content,the Al2O3-SiO2/cellulose composite aerogel changed from honeycomb structure to porous 3D network structure,and the pore size decreased.With volume ratio of 2∶10 between Al2O3-SiO2 sol and microcrystalline cellulose solution,the peak decomposition temperature of 205.21 ℃ and maximum mass retention rate of 35.191％were achieved.The ignition time is 11 seconds and the peak heat release rate is measured at 127.13 kW/m2,demonstrating excellent flame retardant and suppression properties.
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