Flexible Hybrid Silica-Aerogels: Studying the Influences of Different Geometries and Shapes

Kurzfassung

Silica aerogels with their remarkable properties such as low density and thermal conductivity are prime candidates for a wide range of different applications, such as insulation materials in aviation. While pure silica aerogels are very brittle and difficult to handle, adapting the sol-gel process can result in organic-inorganic hybrid-materials with a high mechanical flexibility and a good hydrophobicity while still retaining a remarkable insulation performance. They were first investigated by Hayase et al. [1] and are based on methyltrimethoxysilane (MTMS) and dimethoxydimethylsilane (DMDMS). For aviation applications the properties of this aerogel still have to be improved. Our research is based on a patented recipe of the German Aerospace Center (DLR) [2]. The synthesis was varied towards precursors and their ratios, using different surfactants and catalysts, as well as focusing on shaping the final aerogels into beads and monoliths. Mechanical, thermal, chemical, and morphological properties of the samples were analyzed. With this presentation we will report on a set of experiments focused on synthesizing bead-shaped particles in an emulsion process and comparing their thermal properties to standard monolithic samples. The densities of packed beads and mats is compared, since lightweight is one of the most necessary properties of the final material in aircraft application. Sample sizes vary from lower millimeter (1 - 5 mm) to upper centimeter (> 30 cm) range. Those resulting aerogels can possibly outperform the state-of-the-art compressed fiberglass-mats in aviation applications. The authors gratefully acknowledge funding by the Federal Ministry for Economic Affairs and Climate Action (BMWK) and its Aviation Research Program “LuFo VI-1”. (FKZ: 20Q1908C) [1] G. Hayase, K. Kanamori, K. Nakanishi, J. Mater. Chem. 21, 17077-17079 (2011) [2] R. Fener, P. Niemeyer, European Patent EP3042884A1 (2015)