This study explores the behavior of textile fabrics under thermal exposures. The performance of thermal protective textile fabric systems with different structural features was evaluated under laboratory simulated thermal exposures. The study demonstrated that the protective performance of textile fabric systems varies with different types of thermal exposure. To provide effective protection in flame and radiant-heat exposures, the most important fabric properties to address are emissivity, absorptivity and thermal resistance. In hot surface exposures, the compression property of the fabric systems is the primary feature to consider for protection. Hot water and steam exposures produce mass transfer through fabrics. In the presence of water or steam jet pressure, fabric compression is a primary factor in protecting the human body. The findings obtained in this study can be used to engineer fabric systems that provide better protection from various thermal exposures.

Many thermal sensors can simulate and predict the heat flux transmitted through human bodies under hazardous fire exposures. These sensors are usually used to evaluate the thermal protective performance of firefighters’/industrial-workers’ clothing. This paper presents a thorough review on the latest thermal sensors and their applications in evaluating the performance of protective clothing. Several important aspects associated with the sensor development – constructional features, working principles, and characteristics – were discussed and their applications in protective textile materials testing were summarized. The application procedures of sensors both in heat source calibration and heat flux measurement were introduced. Finally, several research cases were explored. This review could help in understanding basics of the current thermal sensors and their nature in testing protective clothing performance.

The molecule pyridine-3,5-bis(1-methyl-benzimidazole-2-yl), L₁, was shown to form metal–organic gels (MOGs) upon reaction with CuCl₂, CuBr₂ or CdBr₂ in alcoholic solutions. The gels were found to exhibit self sustainability with greater firmness, as suggested by rheological studies. Microscopic analysis, such as POM, SEM and TEM studies, on the MOGs revealed the formation of intertwined gel fibers which provide stability to the gel structures through coordination, hydrogen bonding and π–π interactions. Further crystalline complexes of coordination polymers of L₁ with CdBr₂, HgCl₂, HgBr₂, HgI₂, CdI₂ and CuCl₂ were obtained and their single crystal structures have been determined and analyzed in detail. In these structures, the N-atoms of pyridine and benzimidazole were found to coordinate to the metal centers to yield coordination polymers containing one-dimensional helices and one-dimensional chains with M₄L₄ metallamacrocycles. The structural input from the crystal structures was used to provide probable modes of aggregation in the gels. The MOGs were found to exhibit thixotropic behaviour as well as chemo-responsive behavior. The xerogel materials of the MOGs were found to exhibit an N₂ gas sorption property. Furthermore, they were also shown to have potential application for the treatment of waste water containing organic dyes, such as methyl orange and rhodamin B. Furthermore, the obtained results are compared with the non-methylated derivative of L₁.

Standardized test methods are available for measuring the thermal protective as well as thermo-physiological comfort Performance of fabrics used in firefighters' clothing. However, these tests are usually fabric destructive in nature, time consuming, and/or expensive to carry out on a regular basis. Hence, the availability of empirical models could be useful for conveniently predicting the thermal protective and thermo-physiological comfort performances from the fabric properties. The aim of this study is to develop individual models for predicting thermal protective and thermo-physiological comfort performances of fabrics. For this, different single- and multi-layered fabrics that are commercially used to manufacture firefighters' protective clothing were selected, and the fundamental properties of these fabrics (weight, thickness, thermal resistance, air-permeability, evaporative resistance, and water spreading speed) were measured using the standard test methods developed by the International Organization for Standardization (ISO) or the American Association of Textile Chemists and Colorists. The thermal protective performance of these fabrics was measured by the ISO 9151:2016 test method under 80 kW/m² flame exposure. The thermo-physiological comfort performance of fabrics was determined by the ISO 18640-1:2018 test method and a statistical model. Thereafter, the key fabric properties affecting the thermal protective and thermo-physiological comfort performances of fabrics were determined statistically. It has been found that thermal and evaporative resistances are the key fabric properties to affect the thermal protective performance, whereas the fabric weight, evaporative resistance, and water spreading speed are the key properties to affect the thermo-physiological comfort performance. By employing these key fabric properties, Multiple Linear Regression and Artificial Neural Network (ANN) models were developed for predicting the thermal protective and thermo-physiological comfort performances. Through a comparison of the predicting performance parameters of these models, it has been found that ANN models can more accurately predict the performances of fabrics. These models can be implemented in the textile industry and academia for effectively and conveniently predicting the thermal protective and thermo-physiological comfort performances only by utilizing the key fabric properties.

Mass transfer due to perspired moisture in a clothing system is critical for the understanding of thermo-physiology and thermal protection of a clothed body. Previous studies usually investigated moisture transfer without considering the effect of liquid sweating or external heat hazards. To understand the mechanisms of sweat evaporation, accumulation and dripping with continuous sweating under radiant heat, a multi-phase experiment was designed with a sweating Torso. The concept of clothed wettedness was proposed to understand sweat evaporation of the clothed body. Results showed that the evaporation rate of the clothed body increased with increasing perspiration rate and the rate increase can be explained by the material properties (e.g., material composition, hydrophilicity and evaporative resistance ($R_{\mathit{et}}$ )), which affected the sweat accumulation ability. Results also demonstrated a dual relationship of $R_{\mathit{et}}$ with the evaporation rate of the clothed body. Firstly, the evaporation rate was increased for greater $R_{\mathit{et}}$ due to the higher moisture accumulation. Secondly, when $R_{\mathit{et}}$ exceeded a certain value, the evaporation rate decreased with greater $R_{\mathit{et}}$ due to the reduction in the mass transfer coefficient. For radiant heat exposure, evaporated sweat may condense on the skin surface, decreasing the evaporation rate and increasing the dripping rate. The sweat transfer process was also investigated in detail by the combined analysis of the sweat transfer rate and the evaporative cooling efficiency. This study provides insights into how continuous liquid sweat transfers and evaporates in the clothed body and its interaction with clothing material and environment radiant heat, contributing to the understanding of thermo-physiological burden and thermal protection of the clothed body with intensive activities.

This study characterizes the thermal protective fabrics of firefighters’ clothing under the exposure of hot surface contact. For this, thermal protective performance of different fabrics was evaluated using a laboratory-simulated hot surface contact test, and various factors affecting the performance were statistically identified. Additionally, heat transfer mechanisms during testing were analytically and mathematically modeled. It has been found that fabric’s constructional features and properties are the key factors to affect its thermal protective performance. In this study, the presence of a thicker thermal liner in a layered fabric system resulted in higher performance; in contrast, a multi-layered fabric system incorporating a moisture barrier in its outer layer displayed the lowest performance. Furthermore, it was demonstrated that a fabric’s air permeability has a minimal impact on performance, whereas weight, thickness, and thermal resistance have a significant positive impact on performance. Based on the analytical and mathematical models developed, it was apparent that conductive heat transfer mainly occurs through fabric during testing, and this conductive heat transfer depends upon the surface roughness and thermal properties (thermal conductivity, density, and specific heat) of the tested fabric. Here, thermal contact resistance between the hot surface and fabric also plays a crucial role in the heat transfer or thermal protective performance of fabric. Moreover, the heat transfer gradually decreases across fabric thickness, which can substantially affect thermal protective performance. This study can advance the theory of textile/materials science through better understanding of heat transfer in fabrics. This understanding can help in developing an integrated knowledge of fabric properties, heat transfer through fabrics, and thermal protective performance of fabrics. The findings from this study can also assist textile/material engineers with the development of a high performance thermal protective fabric for clothing to provide better occupational safety and health for firefighters.