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Di-Isocyanate Cross-Linked Silica Aerogels with Btmsh Incorporation

Renee N. Perry, Stephanie L. Vivod, and Mary Ann B. Meador. Structures and Materials Division, NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135

Silica aerogels have potential to be used for numerous applications, including thermal and acoustic insulation for launch vehicles, space suits and aircraft. The low-weight, highly porous structure of an aerogel creates a tortuous pathway that greatly reduces thermal conductivity resulting in a lightweight, insulative material. The underlying silica matrix of the aerogel tends to be very rigid and brittle, which restricts the current applications. Aerogels have been cross-linked with various polymers to enhance structural integrity showing promising results. Previous studies have shown an increase in strength of two orders of magnitude, while only doubling the density. It is also desirable for the aerogels to be flexible. For that purpose, organic linking groups have been added to the underlying silica structure. It is expected that this will help the aerogel recover after compression and exhibit more flexibility. In this study, the effect of cross-linking aerogels with di-isocyanate after adding the organic linking group, 1,6-Bis(trimethoxysilyl) hexane (BTMSH), is being investigated. A design of experiments approach was used to vary the total silicon concentration, the percent organic linker, the percent amine modified silane, and the concentration of di-isocyanate in the polymer solution to determine the effect that each parameter has on the aerogel's properties.