Fabric reinforced polyimide aerogel matrix composites with low thermal conductivity, high flexural strength, and high sound absorption coefficient

Polyimide aerogels show low thermal conductivity and excellent mechanical properties despite their low density. Here, we examine the effect of fabric incorporation into a polyimide aerogel matrix during the gelation process. For this purpose, plain weave fabrics based on high-modulus carbon fibers as well as ultra-high-molecular-weight polyethylene fibers (known as Spectra®) were considered. For a minimal density penalty, only one or two fabrics were incorporated into the aerogel materials. The carbon fabric-based composites outperformed the UHMW polyethylene fabric-based counterparts. The out-of-plane thermal conductivity of the aerogel composites was reduced by approximately half at room temperature with the addition of only one carbon fabric. The incorporation of only two carbon fabrics doubled the flexural strength of the composite materials, but one or two layers of fabric were not enough to statistically alter the ballistic impact performance of these materials in terms of energy absorption per areal density. Both types of fabric-reinforced composite samples showed an almost 4-fold increase in the sound absorption coefficient in comparison with the pristine polyimide aerogels for 2–2.5 kHz. This study shows that for a small change in density and almost no change in volume, one or two carbon fabrics can significantly improve multiple material properties of polyimide aerogels simultaneously.