Mechanical testing of cross-linked silica aerogel impregnated silicone for cryogenic tank applications

Cryogenic propellant tanks used for long duration space missions can experience self-pressurization due to solar radiation. Many technologies have been proposed as means of reducing and/or controlling the rate of vaporization to prevent pressure buildup. Room temperature vulcanizing silicones such as Sylgard-184 and RTV-655 are flexible materials that allow them to be molded into many shapes and geometries. While these materials are known for good thermal insulation, this property can be enhanced by adding components of a superior thermal insulator: aerogels at a various ratios. Aerogels are extremely lightweight materials when compared to silicones due to their porous nature. The highly porous nature of this material has been recognized to be the main reason behind its superior thermal insulating properties. The lightweight and unique thermal insulation capabilities of aerogels make this material useful for space applications. In this work a novel compound material is proposed which takes advantage of the flexibility of silicones and the excellent thermal insulation of aerogels. Ratios of aerogel particles to polymer background that were tested were at 25, 50, and 75 wt. % ratios The mechanical properties of the new material are tested using a bench top tensile tester at both room temperature and 77K. Results are presented that will help predict a compound that can be made with the correct proportions of aerogel to silicone to provide the flexibility and strength for cryogenic propellant tank applications in space. Copyright © 2012 by Jeffrey G. Marchetta