Application of Silica Aerogel in Composites Protecting Against Thermal Radiation

Sylwia Krzemińska,Irena Kamińska,Alicja Nejman,Małgorzata Cieślak

doi:10.2478/aut-2020-0008

Abstract

Abstract Aerogels are characterized by excellent insulation properties and a good resistance to high and low temperatures. The objective of this study was to investigate the effects of silica aerogel on thermal properties of textile–polymer composites. Aerogel was applied in protective clothing fabric to improve its heat resistance. The composites were produced by coating a fabric made of meta-aramid (polyamide–imide) yarns with a dispersion of polychloroprene latex and synthetic resins or an acrylic–styrene dispersion with aerogel (100–700 μm particle size). The composites were subjected to thermal radiation (20 kW/m2) and their thermal properties were determined by thermogravimetry/derivative thermogravimetry (TG/DTG). Scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/EDS) was used to characterize the microstructure and study the elemental composition of materials. The thermal conductivity and resistance of composites were measured with an Alambeta apparatus. The tests indicated an increase in resistance to thermal radiation by approximately 15–25%. In TG/DTG analysis, the initial temperature for an unmodified fabric was 423.3°C. After modification, it decreased to 361.8° and 365.3°C for composites with 7 and 14% of aerogel, respectively. SEM images revealed a reduction in aerogel particle size.

Highlights

In many industries, workers are exposed to flames and other high-temperature factors, such as convective, radiant, and contact heat, which pose significant risks
This study focused on the thermal properties of composites with aerogel coatings as well as their structure and resistance to degradation on exposure to high temperatures
The presented findings demonstrate the considerable application potential of aerogels in materials designed for the heat protective clothing

Summary

Introduction

Workers are exposed to flames and other high-temperature factors, such as convective, radiant, and contact heat, which pose significant risks. Radiant heat transfer depends on the radiation emitted by hightemperature sources and on properties of protective clothing materials [2, 3]. A gel comprising a microporous solid in which the dispersed phase is the gas, is one of the materials which aroused the interest of researchers [4]. Due to their special structure, aerogels are characterized by very good insulation properties under conditions of both high and low temperatures. Silica aerogels are known to be unique porous materials with highly cross-linked network structures revealing a large specific surface area (500–1000 m2/g), high porosity, low density (0.02– 0.2 g/cm3), and very low thermal conductivity (approximately 0.013 W/mK) [5]

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