Wearable Aramid–Ceramic Aerogel Composite for Harsh Environment

Abstract

Nature-based plant fibers with thermal insulation performance have been widely used in wearable textiles such as cloth, gloves, shoes, etc. [1-4] To enhance the thermal insulation of textiles, synthetic fibers with novel structures such as hollow and ultrafine fibers have been developed. [5] Hollow fibers show a higher thermal resistance compared with solid ones while ultrafine fibers perform better than macrofibers. [4,5] However, the fiber textiles usually have a relatively low thermal insulation property in the limited operation temperature range, and weak mechanical properties, which are undesirable in extreme environments. The poly(p-phenylene terephthalamide) or aramid (Kevlar) fibers could meet the harsh requirements of many cutting-edge fields, including aerospace and aviation, electronics, and personal protective clothing, owing to its excellent integrated performances of super fatigue resistance, high specific strength, and thermal resistance. [6-10] Thus, aramid fibers have been widely used as a functional and structural material in protective applications. However, the aramid fibers serving as a thermal barrier in firefighter and first responder protective clothing cannot provide enough thermal protection due to its relatively high thermal conductivity and temperature-sensitive polymeric nature. The longstanding challenge for thermal protection is the inaccessibility of enhanced thermal insulation performance under the harsh environment while maintaining lightweight and robust mechanical performance. On the other hand, the aerogel materials exhibit a highly porous structure, low density, large specific surface area (SSA), and a high thermal insulation performance. [11-13] Ceramic aerogels (e.g., silica aerogels) have a significantly low

The Role and Applications of Aerogels in Textiles

“…e prepared nanocomposites had a low thermal conductivity of 0.026 W/ mK, which is very promising for their use in thermal insulation applications. In another study, An et al [132] prepared ceramic aerogel-aramid fiber textile composite by in situ crosslinking reaction, and it was found that the composite had an excellent thermal insulation conductivity (as low as 0.034 W/mK) with high compressive strength (1.1 MPa).…”

Creation of hollow silica-fiberglass soft ceramics for thermal insulation

“…[16] Blends of hollow silica particles into a polymer matrix to fabricate thermal insulation films can produce robust mechanical properties, [17,41,42] but the intrinsic high thermal conductivity and low melting point of polymers constrain the potential of this class of materials. Recently, some technologies have been developed to reinforce aerogel particles with fibers (polymer fiber or fiberglass), such as electrospinning, [43] hot pressing, [44] and 3D printing, [45] which can produce both excellent thermal insulation and mechanical properties. For example, incorporation of hollow silica nanoshells into a matrix of polymer fibers by electrospinning can yield flexible insulation composite membranes with low thermal conductivities of 0.0236 W m -1 K -1 [46] and 0.016 W m -1 K -1 .…”

Multifunctional Flexible Wearable Kevlar Aerogel Membranes with Breathable and Unidirectional Liquid Penetration Properties for Personal Thermal Management Application

“…In this regard, Yue et al fabricated a laminated fibrous membrane with high solar absorptivity (up to 90%) and infrared reflectance (70%) which improves skin surface temperature by 8.5 °C compared with polyester cloth. Another strategy of thermal management is to reduce the heat convection of wearable materials via controlling air molecule collisions inside the fabric . Aerogel materials have excellent thermal insulation properties due to the pore size of aerogel material being much smaller than the mean free path of the air molecules .…”

“…Another strategy of thermal management is to reduce the heat convection of wearable materials via controlling air molecule collisions inside the fabric. 21 Aerogel materials have excellent thermal insulation properties due to the pore size of aerogel material being much smaller than the mean free path of the air molecules. 22 Following this strategy, Lyuet al 23 fabricated Kevlar nanofiber aerogel/phase-change materials with high thermal management capabilities and infrared emissivities; among them, Kevlar aerogel films have outstanding thermal insulation performances.…”