Air Permeability Research Articles

Effect of deicing salt on air voids and permeability coefficient of asphalt mixture under dry-wet cycle

Although the extensive use of deicing salt has solved the problem of road icing in winter and reduced traffic accidents, it has also had a significant impact on the asphalt mixture. Through dry-wet cycle test, this study investigated the change rule of air voids and permeability coefficient of asphalt mixture under the conditions of different gradation, different deicing salt solutions and different dry-wet cycle times, and analyzed the significant indicators of each factor's impact on air voids and permeability coefficient based on variance analysis. The results showed that the air voids and permeability coefficient of AC-13 and AC-16 asphalt mixtures increased to varying degrees after 0, 5, 10, 15, 20, 25, and 30 dry-wet cycles in 20% NaCl, 15% CH4N2O, and 20% CH2CH3OH solutions, and the air voids and permeability coefficient had a high correlation. Meanwhile, the variance analysis results indicated that gradation was the main factor affecting the air voids and permeability coefficient, followed by the dry-wet cycle times, and deicing salt solutions were the least significant.

Single and hybrid effects of nano‐TiO2 and ‐ZnO particles on multifunctional properties of textiles

AbstractImpregnation of nano‐metal oxides can provide functional properties to textiles, like UV protection and self‐cleaning properties. These properties are quite important as they can provide protection against UV damage, help to reduce cleaning efforts, improve the ease of maintenance, and help to protect the water resources. The usage of nanoparticles improves multifunctional effects due to their high surface area. Therefore, in this study, nano‐sized TiO2 and ZnO were applied to cotton fabrics as single type or hybrids with different concentrations to reveal their effects on multifunctional properties (UV‐protection, self‐cleaning, wettability, photocatalytic activity). Also, the weight and air permeability of samples were determined to evaluate their usability. Scanning electron microscopy, x‐ray diffraction and Fourier transform infrared spectroscopy were also utilized to analyze the samples. According to the results, some samples exhibited good–very good UV protection. Up to 78.5% photocatalytic degradation of organic dye was achieved by nano‐TiO2 application. According to self‐cleaning test results, nano‐TiO2 applied samples showed yellowing after UV irradiation. Hybrid‐coated samples were more advantageous regarding self‐cleaning, especially against cherry juice stains. The staining and wettability results of the samples were in accordance. Weight and air permeability changes were acceptable to maintain the usage of the samples for clothing and other applications.

Durable functionalization of cotton fabric using vanillin as reactive UV protective finish without hampering basic textile properties

Vanillin has been explored exponentially since the last decade due to its inherent functional properties such as antimicrobial activity, UV resistance, fragrance as well as antioxidant activity. Although vanillin has reactive groups such as –OH and –CHO, it cannot be integrated directly into cotton textiles to impart durable functionalities. Because these reactive groups do not form any covalent bond in parent form with the cellulosic backbone and due to its smaller size, its physical bonding with cellulosic structure is also not strong enough to retain themselves into cotton substrates. In the current study, for the first-time, vanillin reactive finish (VRF) has been prepared, characterized using various analytical techniques such as FTIR, Raman spectroscopy, NMR spectroscopy and successfully integrated on cotton fabric. The study substantiates that VRF can transform cotton fabric to an excellent UV resistant textile without altering its color and other basic physical properties (such as bending length, absorption, air permeability and tensile strength, etc.) of the fabric. The washing study has been performed to investigate the wash durability of the finish into cotton fabric. It has been observed that VRF can be retained inside the cotton structure very effectively through covalent bond formation and thus ultra-violet protection (UPF) of the treated textile remains nearly 50 even after 18 machine wash cycles. The presence of finish on the functionalized fabric, even after washing, has been reaffirmed by SEM EDX analysis.

Analytic and Data-Driven Force Prediction for Vacuum-Based Granular Grippers

As manufacturing and assembly processes continue to require more adaptable systems for automated handling, innovative solutions for universal gripping are emerging. These grasping systems can enable the handling of wide varieties of shapes, with gripping forces varying with grasped geometries. For the efficient usage of handling systems, precise offline and online prediction models for resulting grasping forces for different objects are necessary. In previous research, a flexible vacuum-based granular gripper was developed, for which no option for predicting gripping forces is currently available. Various gripping force prediction methodologies within the current state of the art are examined and evaluated. For an assessment of grasping forces of previously untested objects for the examined gripper with limited data and low computational effort, two methodologies are proposed. An analytical, 2D-geometry-derived gripper-specific metric for geometries is compared to a methodology based on similarities of objects to a small existing dataset. The applicability and prediction quality for different object types is analyzed through validation experiments. Gripping force estimations are possible with both methodologies, with individual weaknesses towards geometric features such as air permeabilities. With further development, robust predictions of gripping forces could be achieved for a wide range of unknown object geometries with limited experimental effort.

Enhancing Paper Packaging's Wet Strength Using the Synergy between Chitosan and Nanofibrillated Cellulose Additives.

The demand for eco-friendly packaging materials has urged researchers to look for alternatives to petroleum-based polymers. In this regard, paper-based products have turned out to be a promising choice; however, their weak resistance to water has limited their application. The use of various additives to enhance paper's moisture resistance is a common practice. However, considering the growing global agenda for sustainable development, the search for new bio-based paper additives has become increasingly important. This study investigated the potential synergistic impact of the addition of nanofibrillated cellulose (NFC) and chitosan additives (CHIT) to different fiber combinations to improve paper's properties, in particular, their wet strength. The efficacy of the additive application order was examined and was found to be crucial in achieving the desired outcomes. The results showed that incorporating CHIT after NFC enhanced the paper's tensile and burst indicators, as well as the paper stretch in the dry state, by 35-70%, 35-55%, and 20-35%, respectively. In addition, the tensile index and stretch in the wet state improved 9-13 times and 2.5-5.5 times over, respectively. The air permeability decreased 2.5-12 times over. These findings demonstrate that the sequential addition of the NFC and CHIT additives yield a greater enhancement of paper's properties than using each additive separately.

Potential use of nanofibrillated cellulose-loaded cationic starch solutions as coating formulation for recycled fluting papers

Effects of cellulose nanofibers (CNF) and cationic starch (CS) were evaluated as coating components relative to the physical and mechanical properties of fluting papersheets fabricated from recycled corrugated cardboard fibers. Fabricated fluting papers were subjected to size press applications by three different coating blends. Coating suspensions were prepared at various concentrations of CNF (0.5%, 1%, 2%, 3%, and 4%) and 4 wt% CS, and the same amounts of CS/CNF. The paper sheets were fabricated using size press machine as three-time repetitive applications, followed by one-time drying section, and compared to uncoated, CS-coated, and CNF-coated papers. The application of CNF suspensions increased tensile indices up to 11.7%. Moreover, CS/CNF suspensions resulted in a 67.2% increase in tensile index values. The coating of CS/CNF suspensions increased the burst index values by 163% at the CS+1%CNF concentration when compared to the control pulp. Surface application of prepared suspensions reduced the porosity of the samples under all conditions. The highest reduction in the air permeability was observed in the CS+4%CNF-coated samples as 91.5%. It can be concluded that the superficial applications of CNF on the physical and mechanical properties of recycled fluting paper was more effective in the presence of CS.

Nonreciprocal Intelligent Soundproof Barrier with Active Nonlocal Acoustic Metastructure

Sound insulation is an important issue in daily life and has applications in various scenarios. Conventional acoustic passive metamaterial barriers are designed as a reciprocal sound insulation. However, for some specific application scenarios, unidirectional acoustic insulation is required, which is an enormous challenge for breaking the reciprocity of sound transport with conventional passive metamaterials. Here, a soundproof barrier with nonlocal acoustic metastructure is proposed, which consists of a microcontroller to connect a pair of spatially separated microphones and speakers, to tailoring the acoustic wave transmission for realizing nonreciprocal acoustic insulation. The theoretical calculation and experiment measurement indicated that the active acoustic barrier with a selectable working frequency can realize the suppressive effect in one direction and the enhancive effect in the other direction for an incident acoustic signal. Particularly, the function of an active soundproof barrier can be freely switched to forward, backward, and bidirectional sound insulation by tailoring the nonlocal distance of the digital meta‐atom. Furthermore, this acoustic metastructure is extended from a one‐dimentional waveguide to a two‐dimentional plane to illustrate that it is still valid in an open‐field environment. The proposed customizable nonreciprocal soundproof barriers provide an avenue for many applications in the specific scenarios that require unidirectional sound insulation and high air permeability.

ВОЗДУШНЫЙ РЕЖИМ ВЫСОТНЫХ ЗДАНИЙ

The air regime of multi-stores buildings is formed under the influence of wind pressure, air per-meability of enclosing structures, and the characteristics of the functioning of ventilation systems. The complex task of ensuring standardized air parameters in high-rise buildings is quite complex due to the presence of the stack effect, the action of which in the cold season leads to an increase in infiltration and energy consumption. In design practice, infiltration calculations are carried out using engineering methods that do not provide identical solutions. To assess the impact of in-filtration on the air regime of unique buildings, numerical calculations or modeling in wind tun-nels are used, which have a certain degree of reliability. The paper reviews the work on the influ-ence of the stack effect on the location of the neutral axis of the building and infiltration. One of the main measures to reduce infiltration is the use of façade structures with low air permeability. The selection of façade structures is more reliably carried out taking into account test results. Ex-perimental data are presented for determining the air permeability of a fragment of a modular fa-cade and their comparison with the regulatory requirements of the Russian Federation and differ-ent countries. The discrepancy between the calculation results using engineering methods and test results is shown. It is proposed to use the volume flow coefficient to determine the volume of infil-tration air when the pressure difference changes over a wide range. Tested structures can be rec-ommended for high-rise buildings to ensure the required tightness.

Bionic vine-stems structure for enhancing electrochromic cyclic stability and mechanical stability of multiband spectral regulation fiber

Wearable electrochromic (EC) devices can adjust visible-infrared spectra demonstrate promising potential for applications in display, decoration, personal thermal management, and adaptive thermal camouflage. However, existing flat layer-layer EC devices are hindered by poor air permeability, limited flexibility, and integration difficulties with fabrics, particularly in the realm of intelligent wearables. The creation of highly efficient fiber-shaped infrared (IR) modulation devices with exceptional structural and performance stability represents a significant challenge. We draw inspiration from the arboreous vine-stems structure observed in Chinese wistaria, which effectively minimizes the risk of damage to their vine and stems during harsh weather conditions. We have successfully designed a wearable high efficient multiband spectral regulation fiber (MSRF) with a bioinspired vine-stems structure using carbon fiber and polyaniline (PANI) as the active layer. The planar working electrode (Au) with PANI deposited on its surface was spirally wound around the counter electrode (carbon fiber) and separated by a gel electrolyte (PC/LiClO4), with polyolefin serving as the encapsulation layer. The distribution of electrical potential and lithium ions in the MSRF were analyzed using finite element analysis, demonstrating exceptional electrochromic stability without the length limit of the fiber. Moreover, the MSRF exhibited exceptional IR emissivity (△ε = 0.528) within the 8–14 μm range, fast response time (2.44 s) at low applied potentials (−0.8 V and 0.8 V), robust long-term cycling stability (at least 5000 cycles), and remarkable mechanical stability (at least 5000 bending cycles). The compatibility of the fiber with fabric and potential for patterning using MSRF with high length was also explored, providing new insights into the development of wearable adaptive thermal camouflage and spectral regulation fiber devices.

A skin-conformal and breathable humidity sensor for emotional mode recognition and non-contact human-machine interface

Noncontact humidity sensor overcomes the limitations of its contact sensing counterparts, including mechanical wear and cross infection, which becomes a promising candidate in healthcare and human-machine interface application. However, current humidity sensors still suffer the ubiquitous issue of uncomfortable wear and skin irritation hindering the long-term use. In this study, we report a skin-conformal and breathable humidity sensor assembled by anchoring MXenes-based composite into electrospun elastomer nanofibers coated with a patterned electrode. This composite is highly sensitive to the water molecules due to its large specific surface area and abundant water-absorbing hydroxyl groups, while the elastomeric nanofibers provide an ultrathin, highly flexible, and permeable substrate to support the functional materials and electrodes. This sensor presents not only excellent air permeability (0.078 g cm−2 d−1), high sensitivity (S = 704), and fast response/recovery (0.9 s/0.9 s), but also high skin conformability and biocompatibility. Furthermore, this humidity sensor is confirmed to realize the recognition of motional states and emotional modes, which provides a way for the advanced noncontact human-machine interface.

Stretchable, flexible fabric heater based on carbon nanotubes and water polyurethane nanocomposites by wet spinning process

Wearable heaters are essential for people living in cold regions, but creating heaters that are low-cost, lightweight, and high air permeability poses challenges. In this study, we developed a wearable heater using carbon nanotube/water polyurethane (CNT/WPU) nanocomposite fibers that achieve high extension rate and conductivity. We produced low-cost and mass-produced fibers using the wet spinning. With heat treatment, we increased the elongation rate of the fibers to 1893.8% and decreased the resistivity to 0.07 Ω*m. then wove the fibers into a heating fabric using warp knitting, that resistance is 493 Ω. Achieved a uniform temperature of 58 °C at voltage of 36 V, with a thermal stability fluctuation of −5.0 °C to +6.3 °C when bent from 0° to 360°. Our results show that wearable heaters have excellent flexibility and stretchability, due to nanocomposite fibers and special braided structure, which offer a novel idea for wearable heaters.

Eco-friendly flame-retardant coatings based on γ-ureidopropyltriethoxysilane for cotton fabrics with improved flame retardancy and mechanical properties

In this study, a bio-based coating was constructed by sol-gel technique deposition based on γ-ureidopropyltriethoxysilane (TESPR) and ammonia phytate (AP) to acquire fire-safety cotton fabrics. The flame retardancy, thermal stability, burning behavior, flame retardant mechanism, and mechanical properties of the coated cotton fabrics were evaluated. With about 9.91% weight gain of TESPR/AP coatings, the coated cotton fabrics self-extinguished in the vertical flame test, and the limiting oxygen index arrived at 31%. The thermogravimetric analysis revealed that although the initial thermal degradation temperature of Cotton/TESPR/AP was lower than that of uncoated cotton fabrics, the char residues in the high-temperature range increased. Meanwhile, the results of the cone calorimetry test revealed that both the heat and smoke production released of cotton/TESPR/AP was greatly reduced during burning. The flame-retardant mechanism of this system was eventually suggested depending on the assessment of gaseous products and char residues. Furthermore, TESPR/AP coatings did improve the breaking force of cotton fabrics compared with that of AP coatings, while retained better air permeability compared with that of uncoated cotton fabrics. These bio-based coatings not only ensure safety, but also provide a practical flame-retardant solution for inflammable natural fabrics.

Embedding anatase, rutile, and brookite TiO2 nanoparticles to cotton fabric with epoxy silane and comparison of their effects on photodegradation

Purpose This study aims to embed anatase, rutile and brookite TiO2 nanoparticles (NPs) with different crystal phases into cotton fabrics by epoxy silane and to examine the effect of these applications on the photocatalytic and mechanical properties of the fabric. Design/methodology/approach Different aqueous dispersions which contain anatase, rutile and brookite were prepared at three different concentrations (5%, 10% and 15%). These NPs were embedded in cotton fabrics by using GPTS [(3-glycidyloxypropyl) trimethoxysilane]. Characterization tests were performed by scanning electron microscopy (SEM), Raman and Fourier-transform infrared spectroscopy (FT/IR). Samples were stained with methylene blue (MB) and then exposed to solar light for different periods. Color changes of the samples were examined with a spectrophotometer. Air permeability, abrasion and tear strength tests were applied to all samples. Findings According to SEM images, the NPs were successfully attached to the cotton fabrics, and epoxy silane coating surrounded the fiber surfaces. The presence of the coating was also confirmed by Raman spectroscopy and FT/IR. The treatments reduced the stainability of the samples. The most effective applications for ensuring photocatalytic activity in cotton fabrics were suspensions as 10% brookite, 10% anatase and 5% anatase, in descending order. The applied coating slightly reduced the samples’ air permeability, and wear and tear strength. Originality/value The importance of this study is to determine the optimal crystal phase and its concentration by using epoxy silane to ensure self-cleaning properties on cotton fabrics. The sample treated with 10% brookite is the most approached its original white color by 99.65% as a result of degradation of MB (after 120 min). On the other hand, using the pure rutile with epoxy silane was not suitable for removing MB from the fabric.

Electrospun PCL/gelatin/arbutin nanofiber membranes as potent reactive oxygen species scavengers to accelerate cutaneous wound healing.

The presence of excessive reactive oxygen species (ROS) at a skin wound site is an important factor affecting wound healing. ROS scavenging, which regulates the ROS microenvironment, is essential for wound healing. In this study, we used novel electrospun PCL/gelatin/arbutin (PCL/G/A) nanofibrous membranes as wound dressings, with PCL/gelatin (PCL/G) as the backbone, and plant-derived arbutin (hydroquinone-β-d-glucopyranoside, ARB) as an effective antioxidant that scavenges ROS and inhibits bacterial infection in wounds. The loading of ARB increased the mechanical strength of the nanofibres, with a water vapour transmission rate of more than 2500 g/(m2 × 24 h), and the water contact angle decreased, indicating that hydrophilicity and air permeability were significantly improved. Drug release and degradation experiments showed that the nanofibre membrane controlled the drug release and exhibited favourable degradability. Haemolysis experiments showed that the PCL/G/A nanofibre membranes were biocompatible, and DPPH and ABTS+ radical scavenging experiments indicated that PCL/G/A could effectively scavenge ROS to reflect the antioxidant activity. In addition, haemostasis experiments showed that PCL/G/A had good haemostatic effects in vitro and in vivo. In vivo animal wound closure and histological staining experiments demonstrated that PCL/G/A increased collagen deposition and remodelled epithelial tissue regeneration while showing good in vivo biocompatibility and non-toxicity. In conclusion, we successfully prepared a multifunctional wound dressing, PCL/G/A, for skin wound healing and investigated its potential role in wound healing, which is beneficial for the clinical translational application of phytomedicines.

Window air permeability calculation methodology with regard to temperature loading

Air permeability is an important characteristic of windows, which significantly affects the energy consumption of a building and the quality of indoor climate in winter. Existing experimental studies confirm that the air permeability of windows can increase significantly when the outside temperature decreases. This phenomenon is associated with temperature deformations. Nevertheless, currently in the practice of window design the dependence of air permeability on temperature effects is not taken into account. There are methods of windows air permeability experimental determination that take into account temperature loads, but they require unique equipment and are large labor inputs. In view of this, this paper proposes a semi-empirical method for calculating the air permeability of windows with regard to temperature loads, which uses data from standard laboratory tests. This method is based on identifying the system of infiltration channels, which is formed by the window structure, with an elementary system for which the analytical solution of the infiltration equation is known. It can be used for more accurate calculations of the building's energy consumption in the cold period of time, as well as for obtaining a scientifically justified limitation of window structure deflections under the combined action of wind and temperature loads.

Optimization and development of workwear fabric coated with TiO2 nanoparticles in order to improve thermal insulation properties and air permeability

Workwear clothing is one of the essential personal protective equipment for workers and plays a crucial role in preventing the entry of environmental heat into the body and facilitating thermal exchanges between the human body and the environment. Improving the coating of workwear fabrics while maintaining air permeability is considered an engineering control measure to protect workers in environments with thermal stress. This study aimed to optimize the coating of workwear fabrics with TiO2 nanoparticles to enhance thermal insulation properties and air permeability using the response surface methodology (RSM) and MATLAB. The input variables were the titanium isopropoxide volume and reaction time in the ultrasonic, while the output variables were the coating percent, air permeability, and thermal conductivity coefficients. The morphology of TiO2 nanoparticle and coated fabric (FE-SEM, EDS, FTIR, FTIR-ATR, DLS, and XRD), The intrinsic properties of fabrics (Yarn Count, Abrasion Resistance, Tensile, Tearing Strength), the Water Vapor permeability, Surface wetting resistance, and Durability test were evaluated according to the standard methods. No significant differences were observed in the intrinsic properties between the coated and uncoated fabrics. Increasing the coating percent of fabrics with TiO2 nanoparticles was accompanied with a decrease in the thermal conductivity coefficient and an increase in air permeability. The positive effect of nanoparticle coating is a significant step towards introducing a new generation of smart textiles with the potential to improve thermal insulation properties while maintaining air permeability. This advancement aims to preserve and enhance the health and safety of workers exposed to thermal stress.

3D printing applications on textiles: Measurement of air permeability for potential use in stab-proof vests

The most important piece of safety equipment is developed as a reinforced piece of body armor to resist attacks to the upper parts of the body so as to save the lives of its wearers to offer protection against stabbing with sharp-tipped objects. The majority of commercial stab resistant armors are not comfortable for users to wear during their whole duty shift. The three-dimensional (3D) printing has given great opportunity to develop equipment for a particular and individual application with the incorporation of performance and comfort. Stab protective armor has been developed by 3D printing without compromising the protection performance for a particular energy level to improve the comfort of the armor vest so that users are willing to wear during their whole duty shift. In this study, air permeability is used to measure the comfort tendency of the protective armor as a safety gear without reducing the protection performance. In this study the effect of textile materials and structures, shapes of 3D prints as the segmentation of scales, size of scales, parts of the full vest, attachments, and air exposure sides of the panel are investigated. The result revealed that the air permeability of the 3D printed protective armor vest improved the comfort as compared to the commercially available armor vests of both from a single plate and large sized segmented scales.

Influence of honeycomb structures on fluids transmission and heat retention properties; An initiative towards stretchable weaves

The aesthetics and functionality of honeycomb woven assemblies qualifies them for a range of applications expanding across home textiles, fashion, functional apparels, and technical products. Researchers have explored honeycomb assemblies with the focus on shrinkage, sound absorption, thermal conductivity, and heat protection properties analysis via variation in their cell sizes. However, very minimal research is found on analysis of honeycomb woven fabric assemblies’ thermal comfort characteristics by employing different weft insertion sequence and materials (cotton and stretchable yarns). This study reflects the thermal conductivity, dry fluid transmission (air permeability), wet fluid transmission (moisture management), and stiffness attributes of twelve stretchable honeycomb woven assemblies consisting of single ridge, double ridge, and brighton honeycomb weave structures along with different weft sequences of cotton and Type 400 (T-400) stretch yarns. Characterization data showed that single ridge honeycomb structure supports the highest dry fluid transmission property; however, brighton honeycomb offers the highest heat retention property. Double ridge honeycomb highlights the capability of the highest wet fluid transmission property, and brighton honeycomb has immense stiffness. Statistical analysis (ANOVA) also showed that honeycomb structures, weft yarn sequence and material have a statistically significant impact on thermal conductivity and fluid transmission behaviors with p-values less than 0.05.

Effect of membrane morphology on the thermo-physiological comfort of outdoor clothing

This article examines the effect of membrane type and its morphology on the chosen thermo-physiological properties of the middle layer of outdoor clothing. In total four different membranes were selected for the production and analysis of three-layer laminates, which could replace the second and third layers of layered clothing for sports/outdoor purposes. As an outer and lining material a polyester knitted fabric with fleece was chosen, whereas the lamination technology was used to join the individual layers. Chosen properties affecting the thermo-physiological comfort of the laminates were evaluated, to be able to select a membrane that, in combination with the outer and inner layer, enabled the use of laminate as an upper clothing layer – a jacket, thereby replacing the necessity of using a second clothing layer. The following properties were chosen as crucial: thermal resistance, air permeability, vapor permeability (water vapor penetration), and hydrostatic pressure resistance. The utility value methodology was used to evaluate individual fleece-based laminates. For the completeness of this study, two types of commercially available three-layer laminates containing soft-shell fabric as the top layer were incorporated for comparison.

Investigation of comfort characteristics of knitted fabric produced from neppy yarn

Fabric made from fancy yarn, especially neppy yarn has a great environmental impact because the fabric does not need any additional dyeing process. This study involved knitting neppy yarn of two distinct spinning processes, vortex and ring spinning, each having three different percentages of neps. The comfort properties of six different fabrics were evaluated by analyzing various parameters, including moisture management properties, water vapor transmission rate, air permeability, hand feel properties, and bursting strength. Microscopic views were also examined for analyzing the physical appearance of the fabric’s surface. The experimental results revealed that fabrics made from vortex-spun neppy yarn (VSNY) exhibit better moisture management, breathability, and hand feel properties than ring-spun neppy yarn (RSNY). Alternatively, bursting strength and water vapor evaporation rate showed a lower trend in fabrics made from vortex-spun neppy yarn. The research findings contribute valuable insights into the potential of vortex spinning techniques for sustainable and comfortable textile production.