Fabric Porosity Research Articles

Shrinkage and Porosity of Cotton and Hemp Fabrics Based on ELM Algorithm

Shrinkage and Porosity of Cotton and Hemp Fabrics Based on ELM Algorithm

Characterization of tensile properties of chain stitch structure fabric with negative Poisson’s ratio yarn

Negative Poisson’s ratio textiles have expanded deformation behavior and special mechanical properties under tension. According to the previous research, the negative Poisson’s ratio effect of fabrics was always lower than yarns. The main reason was that negative Poisson’s ratio yarns showed little structural deformation because of the fabric structures. In this study, chain stitch structure fabrics with negative Poisson’s ratio yarns as inserted weft yarns were designed and prepared. The effect of inserted weft yarns, symmetrical and parallelization arrangement and density on the Poisson’s ratio of chain stitch fabrics were tested and analyzed. The results showed that the negative Poisson’s ratio effect of fabrics was as similar as yarns and yarns in fabric. When the knitting loops provided fixation role in the fabrics, the negative Poisson’s yarns could also present obvious deformation behavior to successfully improve the expand effect of fabrics. Poisson’s ratio and porosity of fabrics under cyclic stretching were carried out to study the structure and property stability. The chain stitch structure fabrics with negative Poisson’s ratio are expected to provide more choices for improving the property and applicability.

Humidity-dependency of the relaxation behavior of fabric crease recovery angle

The unfolding of fabric creases induced by humidity is an issue of the capillary forces driving the deformation of materials, related to the interactions of textiles with moisture. Most are about complex moisture transport dynamics in fibrous assemblies. However, the effect of humidity on the crease recovery course of fabric with multiscale structure is not clear. Therefore, the fabric crease unfolding over time in different humidities was explored. In this study, theoretical analysis based on Burger’s viscoelasticity model and experiments on the crease recovery were conducted. Then the evaluation indices, that is, the crease recovery ratio ([Formula: see text]) and the recovery gradient ratio ([Formula: see text]), which were obtained from fitting coefficients and constructed in the form of the theoretical equation, were established. They were then combined with the fabric porosity ( P) at yarn scale, to demonstrate the capillary forces driving the deformation of materials, that is, crease unfolding humidity-induced. The results show that the higher the [Formula: see text] or [Formula: see text] value, the greater capillary forces promoting the crease to recover under the same humidity changes. The smaller the P, the more easily the contacted structures move, and the crease recovers better. In conclusion, the deformations induced by capillary forces are studied in a form of a crease unfolding at a humidity change. The results obtained in this study lay a certain foundation for further research on the mechanism and theoretical model of the moisture on fabric crease recovery.

Janus cotton fabric with Dual-Discrepancies in surface energy and porosity for efficient thermal and moisture management

The Janus fabrics offer potential advantages in moisture management for a comfortable microclimate between our bodies and the environment, but challenges remain in achieving desirable unidirectional sweat transfer and integrating wearing comfort, cost-effectiveness, and fabrication scalability. Here, cotton fabrics are modified on their opposing surfaces to create a Janus structure with dual discrepancies in surface energy and fabric porosity, resulting in improved water transport capability and a well-balanced combination of the mentioned properties. The hydrophobic surface was created by covalently grafting a block copolymer, poly(acrylic acid)-b-poly(lauryl methacrylate), onto one side of a cotton fabric using a “mist polymerization” technique. Porosity differentiation was then achieved by electrospinning silk fibroin (SF) onto the opposite side. The resulting dual-discrepancy in the fabric synergistically enhances its unidirectional transport capability, achieving an outstanding water evaporation rate of 3.0 kg m−2 in 6 h, and at least 2 °C evaporative cooling compared with other conventional fabrics such as cotton and PET. This study demonstrates valuable insights into the development of smart textiles that provide a comfortable microclimate for the human body.

A machine learning approach to characterise fabrication porosity effects on the mechanical properties of additively manufactured thermoplastic composites

The investigation of the mechanical properties of additively manufactured (AM) composite has been the focus of several research over the past decades. However, testing constraints of time and cost have encouraged the exploration of more pragmatic methods such as machine learning (ML) for predicting these characteristics. This study builds on experimental investigations of the flexural, tensile, compressive, porosity, and hardness properties of 3D printed carbon fibre-reinforced polyamide (CF-PA) and carbon fibre-reinforced acrylonitrile butadiene styrene (CF-ABS) composites, proposing the application of ML for predicting these mechanical properties. A comprehensive comparative analysis of various machine learning approaches was executed, with a resultant accuracy ranging between 80 and 99%. The results unveiled the superior predictive performance of ensemble tree learners and the K-NN regressor algorithms when temperature and porosity are selected (based on correlation analysis) as predictors for material hardness and strength in tension, compression, and flexion. In particular, the model built on the extra-tree regressor algorithm demonstrated a remarkably robust fit, with R-squared evaluation scores of 0.9993 and 0.9996 for CF-PA and CF-ABS, respectively. This work develops a ML model that relates porosity to the other mechanical properties of AM composites and the prediction models’ exceptional accuracy, along with their precise alignment with experimental data, provide invaluable insights for the autonomous control and data-driven optimization of the structures.

Comparison of Measured and Calculated Porosity Parameters of Woven Fabrics to Results Obtained with Image Analysis.

Porosity, the measure of the open spaces within a fabric structure, is a decisive factor in the performance of textiles. It influences breathability, permeability to liquids or gases, and suitability for various industries such as apparel, medical, and technical textiles. This study compares classical porosity calculation methods with non-destructive image analysis for 24 woven fabric samples that differ in density and weave pattern. Factors such as fabric density, weave pattern, illumination conditions, magnification, and the influence of the Otsu and Yen threshold algorithms were considered. The multifactor ANOVA statistical analysis shows that fabric density and weave pattern significantly influence porosity, with illumination playing an important role, while the threshold algorithm has a minor influence. A strong correlation is found between the actual fabric porosity and the results of the image analysis, except for double-sided illumination (reflective and transmissive), where the correlation is weakest. This comprehensive investigation provides valuable insights into the reliability of different porosity assessment approaches, which is essential for applications in various textile industries.

Microscopy of Woven and Nonwoven Face Covering Materials: Implications for Particle Filtration.

A suite of natural, synthetic, and mixed synthetic-natural woven fabrics, along with nonwoven filtration layers from a surgical mask and an N95 respirator, was examined using visible light microscopy, scanning electron microscopy, and micro-X-ray computed tomography (µXCT) to determine the fiber diameter distribution, fabric thickness, and the volume of solid space of the fabrics. Nonwoven materials exhibit a positively skewed distribution of fiber diameters with a mean value of ≈3 μm, whereas woven fabrics exhibit a normal distribution of diameters with mean values roughly five times larger (>15 μm). The mean thickness of the N95 filtration material is 1093 μm and is greater than that of the woven fabrics that span from 420 to 650 μm. A new procedure for measuring the thickness of flannel fabrics is proposed that accounts for raised fibers. µXCT allowed for a quantitative nondestructive approach to measure fabric porosity as well as the surface area/volume. Cotton flannel showed the largest mean isotropy of any fabric, though fiber order within the weave is poorly represented in the surface electron images. Surface fabric isotropy and surface area/volume ratios are proposed as useful microstructural quantities to consider for future particle filtration modeling efforts of woven materials.

Porosity determination of textile fabrics: A novel mathematical approach and experimental validation

Porosity is a crucial parameter that regulates permeability, comfort, and pathogen barriers in textile materials. A fabric with greater porosity allows for greater moisture exchange but is less effective as a pathogen barrier. So engineering the fabric to meet both comfort and barrier properties are essential. Various methods (airflow, liquid penetration, and Image processing) are used to determine the fabric's porosity after fabric manufacturing. The mathematical calculation of fabric porosity before fabric manufacturing will become very helpful for precise fabric development. This research paper introduces an innovative and customized mathematical model designed to determine the porosity and pore size of fabrics, utilizing essential parameters such as areal density, thickness, yarn diameter, and yarn linear density. The effectiveness of the modified equation for fabric porosity is tested by using twelve different fabric samples with different areal densities in experiments. The comprehensive testing conducted provides evidence of the adaptability and resilience of the suggested model, highlighting its potential for wider utilization within the sector. The pore size of the prepared fabrics is measured by a capillary flow poro-meter (CFP), and porosity is measured by image analysis using Python programming. A perfect positive correlation has been observed between calculated and experimental porosity values.

Incorporating Variable Porosity into the Determination of Effective Permeability in Interchanging Double Cloth Woven Fabrics Using Darcy's Law.

Woven fabrics are widely used for thermal protection due to their porosity, which provides thermal insulation and breathability. This research focuses on investigating the influential parameters in the thermal protective properties of layer interchanging double cloth, including the woven structure and varying yarn fineness. The properties affecting the protective properties and comfort of multilayered woven fabrics include the fabric thickness, fabric porosity, and air permeability. Darcy's law is applicable for determining the effective air permeability of woven fabrics. By understanding and controlling fabric porosity, it becomes possible to develop thermal protective clothing that combines improved comfort, cost-efficiency, and effectiveness. This study represents a novel approach for the clarification of airflow permeability behavior in complex structures of elastic multilayer woven fabrics using Darcy's law. This innovative approach expands the understanding of permeability in fabrics beyond single-layer fabrics with vertical pores or 3D fabrics used in resin injection processes.

Theoretical Porosity of Elastic Single Jersey Knitted Fabric Based on 3D Geometrical Model of Stitch Overlapping

ABSTRACT To improve the dimensional stability of weft knitted fabrics, spandex yarns are incorporated with the base yarn by the plaiting technique. Adding spandex leads to stitch overlapping, increases the fabric thickness, and affects the pore’s size and distribution. This in turn affects the geometrical and physical properties of weft knitted fabrics such as air permeability. In this paper, the theoretical 3D modeling of stitch overlap, maximum set, and open structures is presented by using AutoCAD software. Fabric thickness was divided into several sections, and the theoretical porosity at each section was analyzed and calculated. Furthermore, single jersey knitted fabrics SJKF with and without spandex were produced to obtain overlapping (by using spandex weight percent, SWP 8%), and open structures. The calculated and theoretical overall porosity were calculated and compared. The study showed the influence of stitch overlapping on fabric porosity. Moreover, the results show that the proposed model captured to some extent the change in fabric porosity as its structure changes.

Plasma-Assisted Green Synthesis of ZnO Directly on Polyethylene Terephthalate Fabric

This article presents green in situ synthesis of ZnO directly on polyethylene terephthalate (PET) fabrics using pomegranate peel extract. The surface of PET was activated by environmentally friendly oxygen plasma, and the process was compared to alkali treatment where the extract of wood ash was used instead of classical chemicals. Sorption analysis showed that the hydrophilic character of the plasma-treated sample was much better than that of the alkali-treated and untreated samples. Both treatments slightly decreased the breaking strength and elongation of the fabric. Scanning electron microscopy, colour measurements, dispersive X-ray spectroscopy, and antioxidant activity investigations showed that the ZnO particles were successfully synthesised on alkali- and plasma-treated PET. The liquid chromatography-mass spectrometry results showed that ellagic acid and punicalagin were the most abundant compounds in the pomegranate peel extract that enabled the synthesis of ZnO. The UV protection, amount of ZnO, and uniformity were the highest for the ZnO prepared on the PET samples by the plasma-assisted green synthesis. Additional optical assessment of fabric porosity and thickness measurements confirmed that these fabrics have excellent UV protection due to the presence of ZnO.

Tobacco and Hot Pot Odor Adsorbed by Cotton, Wool, and Polyester Fabrics: Desorption Components and Dynamic Analysis

Fibrous textiles readily absorb and desorb ambient odors. However, information on the composition and dynamic analysis of tobacco smoke and hot pot odors on fabrics during desorption is limited. This study used gas chromatography–mass spectrometry to analyze the desorption components of cotton, wool, and polyester fabrics exposed to these two odors, respectively. Then, a dynamic diffusion fabric structure model demonstrated the effect of airflow velocity and fabric porosity on nicotine desorption. Furthermore, we proposed mass diffusion coefficients with different molecular weights. The results showed that cotton fabrics with tobacco smoke released many low molecular weight compounds, while with wool fabrics significantly fewer compounds were detected than for the other two fabrics. Notably, 3-ethenylpyridine, a marker of tobacco smoke, was not detected in wool fabrics. For hot pot odor, cotton fabrics released more hexanal, nonanal, and anethole than wool and polyester, while wool fabrics released many β-pinenes. The numerical results of the dynamic model showed that the air inlet velocity significantly affects the nicotine concentration in the fabric. Meanwhile, the concentration of nicotine in fabrics with lower porosity decreased faster. A lower mass diffusion coefficient will cause odors to remain in the fabric. This study aimed at the composition and the dynamics of odor in fabrics and offers essential information and simple models for reducing unnecessary washing of textiles and odor resistance textile design.

Morphological and structural characteristics of Gallium Nitride (GaN) porosity using image processing

Attaining a generalized porosity measurement based on the conventional measuring methods is unfeasible due to thin and complex layers on Gallium Nitride (GaN) film. Therefore, there is an impetus for developing a method of estimating general fabric porosity via image processing techniques. This study is aimed to investigate and validate a new technique for extracting the GaN porosity in terms of morphological and structural characteristics using an image processing technique. The anodization on porous GaN films is prepared by using direct current photo-assisted electrochemical etching (DC-PECE) etching technique. The quantitative structural characteristics based on mathematical morphology is analyzed using Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). To validate the method, the evaluation of porous GaN quality is performed through a non-destructive investigation of its nanostructures using adapting image analysis techniques. Porosity of the structures obtained by calculating the areas occupied by the pores. The quantitative results were obtained and showing good agreement between two modes of measurement and calculation (percentage porosity and pore depth) based on the image-processing data with 91 % and 78 % correlation coefficient.

An electromagnetic wave-transparent model based on plain fabric structural features

Plain fabric structure was analyzed and a predictive model of electromagnetic wave transmission was firstly constructed based on the weighted average method and equations of yarn curved surface, which can be used to predict the wave-transparency of plain fabrics. This model explains that the pitch, porosity, yarn cross-section and thickness of plain fabrics have a mathematical relationship with electromagnetic wave transmission. Five different parameters of S-2 glass fiber plain fabrics were tested in the range of 1∼18 GHz. Wave transmissions were positively correlated with the pitch, porosity and yarn cross-section. Wave transmissions were negatively correlated with thickness. The transmission trends of simulation and measurement were consistent with theoretical results, which proved the correctness of the proposed model.

The Role and Applications of Aerogels in Textiles

Textiles have been used for clothing purposes since ancient times. However, due to their functional properties, their importance—as well as their use in various fields such as filtration, protective clothing, and medical applications—increased over time. Properties of the textile fabrics depend mostly on the fiber type, fabrication technique, and structure. Moreover, fabric porosity is one of the properties that provide comfort, increased thermal insulation, and filtration capability to the end products. The porous structure of woven, knitted, and nonwoven fabrics has been used for many years to get the desired porosity. Usually, macroporous structures are achieved using these types of textiles. Electrospinning is used to produce nanoporous textile fibrous web, but its poor mechanical properties and low production rate limit its use. Aerogels are solid materials with ultrahigh porosity at the nanoscale with low density and good thermal insulation properties, due to which they are considered potential insulation materials today. On the other hand, pure aerogels are sometimes brittle and have poor mechanical properties. Thus, they cannot be directly used in various applications. Consequently, textile reinforced aerogel composites have been developed, which could provide flexibility and strength to aerogels and impart nanoporous structure to textiles. This review summarizes conventional techniques to produce the porous structure in textiles followed by the modern techniques to develop a nanoporous structure. Further, different mechanisms to synthesize textile reinforced aerogel composites are discussed to get a nanoporous structure for filtration and thermal insulation applications. The porosity, mechanical properties, and thermal insulation of textile reinforced aerogel composites are also highlighted. In the end, we give a conclusion that not only summarizes the literature, but also includes recommendations for the researchers.

Durability Study of Thermal Transfer Printed Textile Electrodes for Wearable Electronic Applications.

Textile-based electronics hold great promise because they can endow wearable devices with soft and comfortable characteristics. However, the inherent porosity and fluffiness of fabrics result in high surface roughness, which presents great challenges in the manufacture of high-performance fabric electrodes. In this work, we propose a thermal transfer printing method to address the above challenges, in which electrodes or circuits of silver flake/thermoplastic polyurethane (TPU) composites are prefabricated on a release film by coating and laser engraving and then laminated by hot-pressing to a variety of fabrics and textiles. This universal and scalable production technique enables fabric electrodes to be made without compromising the original wearability, washability, and stretchability of textiles. The prepared fabric electrodes exhibit high conductivity (5.48 × 104 S/cm), high adhesion (≥1750 N/m), good abrasion/washing resistance, high patterning resolution (∼40 μm), and good electromechanical performance up to 50% strain. To demonstrate the potential applications, we developed textile-based radio frequency identification (RFID) tags for remote identification and a large-sized heater for wearable thermotherapy. More importantly, the solvent-free thermal transfer printing technology developed in this paper enables people to DIY interesting flexible electronics on clothes with daily tools, which can promote the commercial application of smart textile-based electronics.

In-situ imaging of advanced materials subjected to in-plane biaxial loading using X-ray micro-computed tomography

This study presents development of a novel in-situ biaxial test that enables microscale observation of deformation and failure in advanced aerospace materials using synchrotron-based X-ray micro-computed tomography (μCT). As a proof of concept, the biaxial test is used to study deformation of a Ripstop Nylon fabric intended for parachute decelerators, and to visualize damage formation in a carbon/epoxy tape-laminate intended for cryogenic propellant tanks. The fabric and laminate specimens are subjected to 1:1 and 1:2 biaxial tension-tension loading, respectively. The X-ray μCT images obtained during in-situ testing of the fabric specimen are used to measure the increase in fabric porosity and straightening of individual fibers. The X-ray μCT images of a biaxially-stressed tape-laminate specimen are used to document initiation and through-thickness evolution of closely-spaced intralaminar stitch cracks. Results from both experiments demonstrate that the new biaxial test enables observations of deformation and damage in advanced aerospace materials that have not been possible using more traditional surface-based observations.

Analyzing the effect of the structural parameters of the fabric substrate layer on the textile FSS shielding properties

PurposeIn this article, the authors intended to analyze the shielding properties of a fabric frequency selective surface (FSS) structure to the basis of substrate fabric properties. For this purpose, the effect of the properties and structural parameters of the substrate fabric layer were analyzed on the shielding properties of the developed FSS.Design/methodology/approachThe experimental and theoretical evaluations were done at the frequency band of 1,805–1,880 MHz and computer simulation technology (CST) was used in modeling. In experiments were developed the FSS structures by different fabrics as the substrate layers and the copper as the patch cells. The shielding properties of these samples were measured experimentally by the developed setup.FindingsConfirming resonant frequencies, transmission coefficients, and the bandwidths results obtained from modeling and experiments show that the thickness, weight and interweaving structure parameters were affect the porosity of the substrate fabric. Porosity of the fabric moves the resonant frequency due to the changing of the dielectric properties of the fabric. Therefore, shielding properties of the FSS structure were affected by these parameters as the important characteristics of the substrate fabric. In addition, shielding properties of the samples (resonant frequencies and transmission coefficients) in different incident angles are not same in two modes of transverse electric and transfer magnetic.Originality/valueThe experimental results suggest that the introduced flexible FSS structures are suitable for shielding applications in the proposed frequency band.

Intermingling pressure level effect on micro polyester melange knitted fabric properties

This study aims at investigating the effects of intermingling pressure level on properties of melange fabrics made of multifilament micro polyester yarns. For this purpose, unit weight, thickness, moisture management, transfer and surface properties of fabrics have been measured, and fabric porosity is analysed by image analysis methods. In addition, image analysis techniques are also used to determine the effect of intermingling pressure level on the visual properties of melange fabrics. Results show that the intermingling pressure level has statistically significant effects on the unit weight, fabric thickness, air permeability, fabric porosity and fabric’s visual properties.

Synthesis of poly(N-isopropylacrylamide) polymer for fabrication of thermo-responsive cotton fabric

Thermo-responsive poly (N-isopropylacrylamide) (PNIPAM) polymer has been synthesized by free radical addition polymerization method. The chemical structure of the synthesized polymer has been clarified by FTIR spectroscopy and 1 H NMR analyses. Turbidity test shows that the synthesized polymer exhibits thermo-responsive properties, depending on change in temperature. Its lower critical solution temperature (LCST) value is measured as 31°C by DSC analysis. The PNIPAM polymer is then applied onto the cotton fabric in two different concentrations using double-bath impregnation method. Change in hydrophilic character of the fabric, which is temperature dependent, has been revealed by drop and absorption capacity tests, contact angle measurement and surface energy calculation. The test results show that the fabrics exhibit thermo-responsive behavior. Their hydrophilic character is turned to the hydrophobic character above LCST of the polymer. The water vapor permeability of the polymer treated fabrics at temperatures above LCST increases as compared to the untreated fabric due to the increase in fabric porosity. Below LCST, water vapor permeability is increased because of the increasing hydrophility. Consequently, it is concluded that the water vapor permeability of the fabrics can be controlled by changing the temperature-dependent hydrophilic/hydrophobic characteristic and porosity, resulting from swelling or shrinkage of the polymer molecules.