Development and material characterization of quartz-reinforced UHTR/aerogel composites : morphology, thermal, and flammability properties

Aerogels are a class of highly porous solid materials with nano-sized open pores. It exhibits unique properties, such as extremely low density and thermal conductivity. The highly porous nature of silica aerogel combined with its high thermal stability also makes it an ideal candidate for thermal insulation under extreme environments. Quartz fibers are almost completely composed of silicon dioxide (SiO₂) and have commonly been used as reinforcement material due to its favorable mechanical and thermal properties. Traditionally, SiO₂ nanofillers have been used as reinforcement material; however, using quartz fiber may provide even greater improvements in mechanical properties than nanosilica powders. The solventless polysiloxane resin (UHTR) is a colorless semi-solid resin system that exhibits very high char yields and thermal stability. This grade of UHTR is formulated using proprietary polysiloxane chemistries to tailor it for flame shielding applications. In this study, the objectives are to develop processing methods to disperse aerogels and chopped quartz fibers thoroughly and homogenously into a polysiloxane resin and to investigate the processing conditions on morphology and thermal properties of a quartz fiber-reinforced aerogel composite material. The proposed composite exhibits high char yield, low density, and low thermal conductivity properties. The goal of this study is to create a quartz fiber-reinforced polysiloxane/aerogel composite that possesses low thermal conductivity and high char yield suitable for advanced aerospace and defense applications.