Properties of laminated silica aerogel fibrous matting composites for footwear applications

This paper describes a lamination method of commercially produced silica aerogel composite and investigates its suitability for thermal insulation within protective footwear applications for severe cold and extreme high-altitude environments. A silica aerogel composite was used with a thickness of 2.7 mm and mass per unit area of 500 gm ^–2 . Silica aerogel dust, which is generated during the crushing of brittle silica aerogel, was prevented from spreading into the environment by two-sided lamination of silica aerogel composite. A solid 5 µm thick membrane was used, reinforced with an abrasive resistant polyester knitted fabric. The thermal conductivity of laminated silica aerogel composite was comparable to that of the non-laminated one and amounted to 0.016 Wm ^–1 K ^–1 . Water vapor permeability of the laminated silica aerogel composite was 1.31 mgcm ^–2 h ^–1 . The silica aerogel composite was subjected to 30,000 cycles of flexing in order to study the impact of its irreversible crushed structure on the water vapor permeability and thermal resistances of laminated samples. It was observed that flexing did not damage the membrane of the laminated composite and had no statistically significant effect on its thermal resistance and water vapor permeability. During this study it was confirmed that the newly developed laminate has potential applications within protective footwear for extreme cold temperature environments.