Thermal Resistance Of Fabrics Research Articles

Design and properties of shape memory sports bras for comfortable pressure based on ergonomics

To improve the difficulty in wearing and uncomfortable pressure of the sports bra, shape memory polyurethane filaments (SMPUFs) were used to prepare seamless sports bras in this study. Five fabric samples with different stitch structures and yarn were prepared. Then shape memory sports bras were designed based on the properties of the different fabric samples and female body characteristics. SMPUFs were characterized by differential scanning calorimetry for the thermal properties. Shape memory properties and mechanical properties of the SMPUFs, covered yarn and fabric samples were measured. Besides this, the moisture absorbency, permeability and thermal resistance of fabrics were tested. A pressure test system was set up and the pressure of the sports bras was investigated at different temperatures. The results showed that the transition temperature ( Ttrans) of the SMPUF was 27.33°C, which could be triggered by human skin temperature. The best shape fixity ratio of the fabric sample was 82.5% and the shape recovery ratio was 94.4%. The comfortable pressure of the shape memory sports bra at the mean human skin temperature of 34°C was 1.6–5.6 kPa.

Thermal resistance prediction of aerogel fabrics after repeated washing based on small-sample data

Aerogel fibers utilized in thermal protective apparel exhibit exceptional heat insulation capabilities; however, concerns arise regarding potential degradation due to the detachment of aerogel particles during repeated washing. Accurate prediction of aerogel fiber thermal resistance is critical for assessing hydrothermal aging in aerogel textiles, yet the precision of such predictions is significantly hindered by limited sample data and numerous uncertainties constrained by testing time and expenses. The present study endeavors to ascertain the optimal parameters dictating aerogel fabric thermal resistance post-washing and establish a prediction model based on these variables using small-sample data. Four aerogel fabric candidates were selected and subjected to multiple washing cycles (0, 1, 5, 10, 15, and 20 cycles). Gray relational analysis (GRA) was initially employed to prioritize the primary thermal resistance parameters, thereby identifying the interrelations among various factors and circumventing the unreasonable equal treatment of samples in conventional gray predictions. Subsequently, a discrete gray linear regression (DGLR) algorithm was proposed and validated to estimate thermal resistance using input from four principal fabric parameters: the fabric weight, thickness, air permeability, and surface temperature distribution coefficient. The findings revealed that the GRA-DGLR model achieved relatively high accuracy, closely aligning with the experimental results. Following repeated washing, aerogel fabric thermal resistance diminished, with the air permeability, weight, thickness, and surface temperature distribution coefficient ranked in descending order of significance. This investigation highlights the considerable impact of repeated washing on aerogel fabric thermal resistance and the efficacy of the GRA-DGLR model in estimating this parameter.

Modification and Validation of a Dynamic Thermal Resistance Model for Wet-State Fabrics

To investigate the dynamic thermal resistance of woven fabrics in different wetting states, ten commonly used clothing fabrics were selected and tested for fabric thermal resistance under different levels of water saturation in accordance with Chinese national standards. Based on Mangat’s eight thermal resistance prediction models, the study improved the models by replacing the original moisture content with water content saturation. The suitability of the eight models in predicting the thermal resistance of woven fabrics in wet states was compared using the sum of squared deviations (SSD), sum of absolute deviations (SAD), and correlation coefficient (R2). The results showed that during the process from initial wetting to complete immersion, the measured thermal resistance values of the ten fabric samples were consistent with the predicted values from Model 5 in the theoretical model of thermal resistance (R2 > 0.955). The characteristic of Model 5 is that the air thermal resistance and water thermal resistance are first connected in parallel and then connected in series with the fiber thermal resistance. The corrected predicted values from Model 5 were highly consistent with the experimental measurement values and can be used to approximate the thermal resistance of woven fabrics in wet states.

Optimization of Knitted Fabrics for better Thermo-Physiological Comfort by using Taguchi-based Principal Component Analysis

The water, air permeability and thermal resistance of fabrics are important attributes that have a significant impact on the thermal comfort properties of sportswear fabrics in different environmental conditions. In this work, terry and fleece fabrics were developed by varying the fibre content and mass per unit area of fabrics. Moreover, the thermo-physical properties of the developed fabrics, including air permeability, water vapor permeability and thermal resistance, were analysed before and after washing. The multi-response optimization of the thermal comfort properties of knitted fabrics was performed using principal component analysis (PCA) and the Taguchi signal-to-noise ratio (PCA-S/N ratio) to achieve optimal properties. It was determined that the selected parameters (fabric type, finishing, fibre content and fabric mass per unit area) had a significant effect on the thermal comfort properties of knitted fabrics. The PCA analysis showed that 100% cotton terry fabric before washing with an aerial weight of 220 g/m2 had higher air and water vapor permeability value, but a lower thermal resistance value.

Influence of flock coating on the thermophysiological comfort properties of woven cotton fabric

In flock coating, the fabric surface is coated with an adhesive, and flock fibers of a certain length and fineness are impinged and embedded on the adhesive. Embedded fibers form a pile structure on the surface, causing the process to find a wide range of applications. However, there has been no study on the comfort properties of the flock coated fabrics due to the inevitable decrease of the fabric permeability after adhesive coating. This study evaluates the flock fiber physical properties, adhesive coating ratio, and flocking duration on the comfort properties of flock-coated fabrics. Three different coating ratios, two different flocking durations, and four different flock fibers with different fineness and length were studied. Fabric samples were produced by electrostatic flock coating of the woven cotton base fabric. In addition to the experimental study, a mathematical model has been set up to predict the flock-coated fabric thermal resistance. Short (0.4 mm) and long (1.0 mm) flock fibers have assured 82% and 204% higher thermal resistance, respectively, compared to the base fabric thermal resistance of 7.37 (10−3 m2 K/W). The thermal resistance mathematical model results have been found to agree with the actual values with a correlation coefficient of 0.95. Compared to the base fabric, long flock fiber has provided a 249% increase in thermal resistance, with at most a 20% fabric mass increment and 24% relative water vapor permeability decrease. The findings indicate that flock coating can be utilized in cold-weather clothing.

Precision of Measurement of Water Vapor Resistance of Fabrics With Different Surface Roughness by a Skin Model

Skin models are used for determination of water and thermal resistance of fabrics. Measurement in these instruments starts with determination of water vapour resistance of a boundary layer above the sweating hotplate. In the second step, the hotplate is covered by the tested fabrics and the instrument measures WV resistance of the fabric and that of boundary layer. Afterwards, the difference between these measurements presents the required WV resistance of the measured fabric, provided that WV resistance of the boundary layer is in both measurements identical. However, fabric surface roughness may change WV resistance of the boundary layer in the second measurement. In the paper, the effect of the fabric surface on measurement precision is theoretically analyzed and experimentally verified by procedure, which provides same air surface friction during both steps of the measurement. Experiments confirmed certain but small effect of the fabric surface roughness on the measurement precision.

Thermal Comfort Properties of Bamboo/Silk Fabrics

The thermal resistance of fabrics containing silk showed a higher value in comparison with lyocell-rich blends. The water vapour permeability, absorbency and wickability of lyocell and lyocell-rich blends were found to be superior as compared to 100% silk fabrics. With respect to aesthetic comfort properties, the drape of the lyocell rich fabrics was good in comparison with 100% silk fabrics.

Effect of fabric structural design on the thermal properties of woven fabrics

The thermal properties of a certain fabric govern its end usage. The enhanced thermal resistance can help to use light weight fabric for cold conditions. The aim of this study was the development fabric with a particular structural design having enhanced thermal resistance, without any change in the constituent materials or any extra process. Fabric samples were produced using cotton and core spun elastane yarns along weft, in a specific sequence. The fabrics had either a flat or puckered appearance, depending on the arrangement of weft yarns. It was observed that the percentage of core spun yarns and fabric thickness had a significant effect on the thermal resistance of fabrics. A valuable difference in the thermal resistance of flat and seersucker (puckered) fabrics, having same construction was observed. It was found to be the effect of the characteristic puckered effect of the seersucker fabric. Statistical models were developed to predict the thermal resistance of flat fabrics using core spun yarns percentage and fabric thickness.

Effect of perspired moisture and material properties on evaporative cooling and thermal protection of the clothed human body exposed to radiant heat

Perspired moisture plays a crucial role in the thermal physiology and protection of the human body wearing thermal protective clothing. Until now, the role of continuous sweating on heat transfer, when simultaneously considering internal and external heat sources, has not been well-investigated. To bridge this gap, a sweating torso manikin with 12 thermal protective fabric systems and a radiant heat panel were applied to mimic firefighting. The results demonstrated how the effect of radiant heat on heat dissipation interacted with amount of perspired moisture and material properties. A dual effect of perspired moisture was demonstrated. For hydrophilic materials, sweating induced evaporative cooling but also increased radiant heat gain. For hydrophilic station uniforms, the increment of radiant heat gain due to perspired moisture was about 11% of the increase of heat dissipation. On the other hand, perspired moisture can increase evaporative cooling and decrease radiant heat gain for hydrophobic materials. In addition to fabric thermal resistance ( Rct) and evaporative resistance ( Ret), material hydrophilicity and hydrophobicity, emissivity and thickness are important when assessing metabolic heat dissipation and radiant heat gain with profuse sweating under radiant heat. The results provide experimental evidence that Rct and Ret, the general indicators of the clothing thermo-physiological effect, have limitations in characterizing thermal comfort and heat strain during active liquid sweating in radiant heat. This paper offers a more complete insight into clothing thermal characteristics and human thermal behaviors under radiant heat, contributing to the accurate evaluation of thermal stress for occupational and general individuals.

Obtaining the thermal resistance of air enclosed at the interface of multilayer fabrics by simulation

An air layer enclosed at the interface was largely responsible for the insulation results of multilayer fabrics obtained from experiments. In this study, a three-dimensional finite element method model, in which the air layer enclosed at the interface of multilayer fabrics was ignored, was developed to calculate the fabric thermal resistance, and the result obtained from the fabric model was independent of the air. A Thermolab II Tester KES-F7 was also used to measure the thermal resistance of fabrics, and the experimental results were influenced by the air layer. By comparing the simulation and experimental result, the air layer thermal resistance was determined, and then an estimating equation, which can be used to estimate the fabric and air layer thermal resistance for multilayer fabrics, was proposed. The results suggested that the surface roughness of fabrics was strongly related to the air layer thermal resistance, with a linear relationship between them. Moreover, for multiple layers stacked by different fabrics, the air layer thermal resistance at the interface was mainly decided by the fabric with the rougher surface. An estimating equation was also developed to predict the thermal resistance of multilayer fabrics and good correlation between predicted and experimental values was observed.

Application of artificial neural network (ANN) for the prediction of thermal resistance of knitted fabrics at different moisture content

Thermal resistance of the fabrics is one of the decisive parameters in terms of comfort; however it can change due to wetting. Therefore, thermal resistance of wetted fabric is important for comfort performance of garments. In recent years, artificial neural networks (ANN) have been used in the textile field for classification, identification, prediction of properties and optimization problems. ANNs can predict the fabric thermal properties by considering the influence of all fabric parameters at the same time. In this study, ANNs were used to predict thermal resistance of wetted fabrics. For this aim, two different architectures were experienced and high regression coefficient (R2) between the predicted (training and testing) and observed thermal resistance values were obtained from both models. The obtained regression coefficient values were over 90% for both models. Then it can be said that ANNs could be used for predicting thermal resistance of wetted fabrics successfully.

Characterization and statistical modelling of thermal resistance of cotton/polyester blended double layer interlock knitted fabrics

The aim of this study was to analyse and model the effect of knitting parameters on the thermal resistance of cotton/polyester double layer interlock knitted fabrics. Fabric samples of areal densities ranging from 310-495 g/m2 were knitted using yarns of three different cotton/polyester blends, each of two different linear densities by systematically varying knitting loop lengths for achieving different cover factors. It was found that by changing the polyester content in the inner and outer fabric layer from 40 to 65% in the double layer knitted fabric has statistically significant effect on the fabric thermal resistance. Fabric thermal resistance increased with increase in relative specific heat of outer fabric layer, yarn linear density, loop length, and fabric thickness while decrease in fabric areal density. It was concluded that response surface regression modelling could be successfully used for the prediction of thermal resistance of double layer interlock knitted fabrics. The model was validated by unseen data set and it was found that the actual and predicted values were in good agreement with each other with less than 10% absolute error. Sensitivity analysis was also performed to find out the relative contribution of each input parameter on the air permeability of the double layer interlock knitted fabrics.

Effect of Slub Yarn Ratio on Single Jersey Knitted Fabric Properties

Slub yarns are widely used in Single Jersey knitted fabrics to improve their appearance. This research aims to study the influence of slub yarn ratio on physical and mechanical properties of Single Jersey knitted fabric. Ten single jersey knitted fabrics were produced using four different ratios of slub yarns at two levels of ground yarn counts. Physical properties of knitted fabric were measured such as fabric density, thickness, shrinkage, spirality, color properties and thermal comfort properties. Also, mechanical properties of knitted fabric were measured including bursting strength and abrasion resistance. Results showed that increasing percentage of slub yarns used up to 50% improved fabric density, spirality and shrinkage after repeated washing, while the weight loss percent due to abrasion decreased. Fabric thermal resistance increased and air permeability decreased; while there were no significant changes observed in other measured properties.

Thermal resistance of fabrics vs. thermal insulation of clothing made of the fabrics

The protection of a human body against the negative environmental factors, especially the cold, is one of the crucial functions of clothing. Clothing creates a thermal barrier between the human body and the surroundings. The protective efficiency of clothing goods depends mostly on thermal insulation properties of textile materials applied in clothing. The clothing design, fitting to a user’s body, and a number of layers also play an important role in the phenomenon of the heat exchange between the human organism and its surroundings. The thermal insulation properties of textile materials can be measured by means of different testing devices, such as the “skin model,” the Alambeta, the Permetest, and the Thermo Labo. A measurement of clothing goods from the point of view of their thermal insulation is performed using a thermal manikin. The article presents an investigation of thermal insulation properties of vests by means of thermal manikin. The investigated vests have been made of different textile materials: woven and knitted. The thermal insulation properties of fabrics applied in vests have been measured by means of the Alambeta. The article presents and discusses the relationships between the thermal insulation of vests according to the thermal manikin and the thermal resistance of fabrics applied in the vests.

Simplified Model for Predicting Fabric Thermal Resistance According to its Microstructural Parameters

School of Textile and Materials Engineering, Dalian Polytechnic University, Dalian, Liaoning, 116034, China Corresponding author: Ju Wei. E-mail:13238056518@163.com Abstract This paper presents a modified model to calculate the thermal resistance of woven and knitted fabrics according to the microstructural parameters. The model was established by analysing the heat transfer process in the simplified basic unit of the fabrics. The model was modified and checked by experimental values of various fabric samples. Pearson correlation coefficients between the thermal resistance and fabric structural parameters were calculated. Results indicate that fabric thermal resistance can be predicted by the modified equation satisfactorily. The Pearson correlation coefficient from high to low follows such a sequence: fabric thickness, fabric volume density, fabric structural parameter a, fibre volume density, and fibre thermal conductivity.

Thermal resistance models of selected fabrics in wet state and their experimental verification

This study investigated the structural model of textile fabrics affected by moisture. The model has been verified through five fleece fabrics made up of various textile materials and subjected to several mechanical surface treatment levels. Thermal resistance is one of the key parameters of thermal comfort along with water vapor permeability. In recent times, a keen interest has been focused on the mathematical modelling of this parameter and its experimental verification. However, most of these efforts are made to describe dryness in thermal resistance of fabrics, ignoring the wet condition found in protective and outdoor clothing. To determine the thermal resistance value of the studied fabrics, the ALAMBETA semiautomatic nondestructive thermal tester was used. The findings show that the proposed model displays substantial harmony with the experimental data.

Study on thermal resistance of multilayered fabrics under different compressional loads

In this work, the thermal resistance of multilayered fabric ensembles meant for cold weather conditions were studied under different compressional loads. An instrument has been developed to study the thermal resistance of fabrics under different compressional loads. The instrument consists of a test plate, guard plates and a bottom plate. The test plate and guard plates were assembled together as a single entity, which can be moved up and down with a screw shaft. A load cell was connected to the plate assembly to apply the required compressional load on the fabric specimen. Thermal resistance of multilayered fabrics was studied in the developed instrument under different loading conditions. Single-jersey knitted fabric, needle punched fabric and polytetraflouroethylene (PTFE) coated fabrics were used in the inner, middle and outer layer, respectively. Twenty different multilayered fabric ensembles with the same inner and outer layers were studied. The middle layers, i.e. needle punched nonwoven fabrics, were produced from polyester hollow fibres, with varying linear density of fibre, mass per unit area and punch density. The thermal resistance of multilayered fabrics obtained from the developed instrument was compared with the thermal resistance of instruments, namely sweating guarded hot plate (SGHP) and Alambeta. Regression equations were developed and the contour plots were drawn to analyse the effect of the fibre, fabric and process parameters. ANOVAs were conducted to find the significance of the compressional load, linear density of fibre, mass per unit area and punch density on the thermal resistance of fabrics. It was found that the thermal resistance obtained from the instrument follows the same trend as that of thermal resistance obtained from SGHP and Alambeta. Mass per unit area was found to have significant effect on the thermal resistance of multilayered fabrics under different compressional loads. The effect of punch density decreases with the increase in compressional load on the thermal resistance of multilayered fabrics. The thermal conductivity of multilayered fabrics was observed to increase with the increase in the compressional load.

Predicting thermal resistance of cotton fabrics by artificial neural network model

This paper presents the prediction of thermal resistance of handloom cotton fabrics by artificial neural network models using four primary fabric construction parameters, i.e. ends per inch (EPI), picks per inch (PPI), warp count and weft count as the inputs. ANN model with seven nodes in the single hidden layer exhibited the overall best performance with coefficient of determination of 0.90 and 0.86 and mean absolute error of only 5.13% and 4.23% during training and testing respectively. The importance of fabric construction parameters on the thermal resistance of fabrics was also analyzed by the developed ANN model. Weft count, EPI and warp count were found to be the first three most important fabric constructional parameters in descending order of importance in predicting thermal resistance of plain woven cotton fabrics.

Modelling the thermal resistance of woven fabrics

Thermal resistance of fabrics is an important property influencing an ability of fabrics to protect the human body against cold. In this paper the model of the thermal resistance of woven fabrics is elaborated. Next, an experimental verification was carried out on the basis of the results for 26 cotton woven fabrics of plain weave as well as for 18 cotton fabrics of weaves different to plain. The experiment confirmed that there is a statistically significant and strong correlation between the real values of the fabric thermal resistance measured by means of Alambeta and the predicted value calculated by means of the elaborated model.

Comparing different approaches to in situ measurement of building components thermal resistance

This paper introduces a comparison of different measuring methods of buildings fabric thermal resistance, including the test wall measuring points arrangements and measurement results, conducted in a test chamber in Cagliari (Italy) in summer 2009.Two methods and their measurement uncertainties are presented and compared by the compatibility of measurement study.The non-destructive method involves the heat-flow rate measurement through the test wall and its surface temperatures. The reliability of this method depends on the temperatures difference between the two environments separated by the building envelope. Thus two measurement series with different temperatures were carried out on the test wall.The destructive method instead foresees the acquisition of a sample by the use of a hollow drill, the building envelope layers thickness measurement and the thermal properties assignment to each different material. The wall R-value is the sum of each layer thermal resistance.The comparison shows that the R-values measured by the non-destructive method with a temperature difference of 10°C and 7°C and the one calculated from the destructive method obey the compatibility of measurement principle.