Radiant Heat Protective Performance of Clothing Assemblies with Flexible Aerogel-Nomex Nonwoven Composite As Thermal Insulation

In order to achieve a superior level of heat protection, aerogel-Nomex nonwoven composite felts have been prepared and used as middle layer in 3-layered fabric. To study the effect of precursor concentration on the radiant heat protection, methyltrimethoxysilane (MTMS) precursor to methanol molar ratios are varied for making the flexible aerogel-Nomex nonwoven felt. The heat protective performance of three-layered clothing assemblies, with aerogel-Nomex nonwoven felt as the thermal insulating middle layer [outer layer Nomex IIIA woven and inner layer modacrylic-cotton (60:40) woven fabric] has been determined by exposing the clothing combinations to pure radiant heat fluxes by using Stoll's criterion. The use of aerogel-Nomex nonwoven fabric shows more than 100% increase in the heat protection time as compared to the conventional multilayered heat protective clothing assembly. The aerogel-Nomex nonwoven fabric samples produced using MTMS precursor are found to be soft and flexible as compared to the conventionally produced pure silica aerogels, by using tetra-alkoxysilanes, which are normally fragile in nature.