Silica Aerogel as Super Thermal and Acoustic Insulation Materials

Yanru Lu,Hai Huang,Xijiang Yin,Xiaodong Li,Neng Fu Tao,Handojo Djati Utomo

doi:10.4236/jep.2018.94020

Abstract

Silica aerogels are light weight, nanostructured, and highly porous materials with an open pore structure. Due to their excellent characteristics, such as extremely low thermal conductivity, low density and high porosity, the silica aerogels become promising potential adsorbents, catalysts, thermal insulation, and acoustic absorption materials for environmental purposes. This paper presents the synthesis of a highly flexible polymer modified silica aerogel with the use of a cellulose-methyltriethoxysilane (MTES) precursor in a two-step acid-base catalyzed sol-gel process. The physical properties of the resulting aerogels were characterized by thermogravimetry, scanning electron microscopy, nitrogen adsorption-desorption, contact angle, thermal conductivity measurements, compression testing and Fourier transform infrared spectroscopy. The fabricated aerogel exhibited high flexibility with a Young’s modulus of compression of 0.33 MPa and the density of 0.132 g/cm3. They were hydrophobic in nature and had low thermal conductivity. Preparation of aerogel with solid waste (fly ash/bottom ash) is also discussed. The preliminary results showed that the materials have great potential for environmental application, i.e. enhancement of solid waste recycling rate by converting waste to high value-added materials, super thermal and acoustic insulation materials in green building and removal of oil spilled into surface drainage.

Highlights

The preliminary results showed that the materials have great potential for environmental application, i.e. enhancement of solid waste recycling rate by converting waste to high value-added materials, super thermal and acoustic insulation materials in green building and removal of oil spilled into surface drainage
As shown by the increment in the density of aerogel sample in Figure 5(b), increasing the cellulose concentration to above 0.9 wt% adversely affects the porosity of the nanostructure of the aerogel
This is consistent with the surface area correlation (Calculated from the nitrogen adsorption isotherms that are shown in appendix) with porosity reported [28] for cellulose whereby higher concentrations of cellulose result in lower porosity and higher density

Summary

Introduction

Aerogels are the world’s lightest solid materials and have the lowest thermal. Silica aerogel is commonly synthesized by either water glass or alkoxides. Samuel Kistler produced the first aerogel by water glass [4], whereas the alkoxides approach is currently more popular because it requires fewer solvent exchanges [5]. The process of aerogel includes two steps: formation of lyogel by water glass or alkoxide and drying (replacement of solvent by air). Shrinkage of the gel caused by capillary force in gel pores will lead to a collapse and thereby a failure of aerogel formation [6]. There are at least four routes to produce aerogels via different gel formations and drying processes

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Conclusion