Low Air Permeability Research Articles

Evaluation on the Air Permeability Properties of the Mainstream Sportswear Brands

The present study investigated the air permeability of three representative sportswear brands products (OUDIKE, NIKE and an unknown brand bought from the boutique) in Hong Kong marketplace. It was found that NIKE sportswear had the highest air permeability (0.23kPa*s/m) among the samples, which indicates that it allows more air flow passing through the textile and provides good comfort property to wearer, while OUDIKE samples showed the lowest air permeability in capacity (0.08kPa*s/m). The fiber content and fabric structure may be the reason that affects the air permeability. This study would provide a comparative information about air permeability property of the mainstream sportswear brands product in Hong Kong market.

Evaluation of compression-recovery and thermal characteristics of multilayer bedding textiles

PurposeDesign of bedding textiles that contact the human body affects the sleep quality. Bedding textiles contribute to comfort sense during the sleep duration, in addition to ambient and bed microclimate. The purpose of this study is to evaluate the effects of different layer properties on the compression recovery and thermal characteristics of multilayer bedding textiles.Design/methodology/approachIn this study, woven and knitted multilayer bedding textiles were manufactured from fabric, fiber, sponge and interlining, respectively. Different sponge thickness, fiber and interlining weight were used in the layers of samples. Later, the pilling resistance, compression and recovery, air permeability and thermal conductivity of multilayer bedding textiles were investigated.FindingsThe results indicated that samples with the higher layer weight and thickness provide better compression recovery and lower air permeability properties. It was also found that knitted surfaces show the higher air permeability than the woven surfaces depending on the fabric porosity. Layer properties have insignificant effect on the thermal conductivity values.Originality/valueWhile researchers mostly focus on thermal comfort properties of garments, there are limited studies about comfort properties of bedding textiles in the literature. Furthermore, compression recovery properties of bedding textiles have also a great importance in terms of comfort. Originality of this study is that these properties were analyzed together.

A research on effect of surface treatment conditions on flammability and water repellency properties of drapery fabrics produced from micro polyester yarns

Flame retardancy and water repellency are frequently applied finishing processes for drapery fabrics. These two treatments should require special attention when they are applied consecutively. This research aims to investigate the effect of sequential finishing processes by utilizing of different flame retardant chemical ratio (0, 60 and 90 g/l) and fluorocarbon based water repelling substance ratio (0, 10 and 30 g/l) on hydrophobic, flammability, air permeability and stiffness properties of the drapery fabrics. According to the results of statistical analyses, it was determined that fabric burning behaviour, air permeability and stiffness properties were significantly influenced from the process types with different finishing substance ratios and from the weft yarn density as well as from the interaction of process type and weft yarn density at 0.05 significance level. Additionally, process type was a significant factor on water repellency of drapery samples however weft yarn density and the interaction of weft yarn density and the process type were not influential factors on water repellency at significance level of 0.05. For both warp and weft fabric directions, lowest damage zone at the length and width with the ignition source was obtained from the samples which were only treated with flame retardancy process without water repellency (90-0 coded process). The most satisfying results in terms of water repellency were obtained from the samples treated with 60-30 coded process where 60 g/l FR and 30 g/l water repellent chemical substances were utilized respectively. Drapery fabrics treated with 60-0 coded process revealed the best windproof feature indicating the lowest air permeability.

The quantitative analysis for the formation of carbon fiber paper and its influencing factors

Carbon fiber paper (CFP) has been widely investigated as a gas diffusion layer for high-performance fuel cells, while the paper formation, one of the most important properties of CFP, has been rarely reported before owing to the lack of accurate characterization methods. Herein, using a 2D laboratory sensor, a quantitative analysis was conducted to comprehensively analyze CFP formation, carbon fiber (CF) flocs and their influencing factors. Within the study scope of this paper, improved paper formation was always accompanied with a smaller floc area and a lower ratio of large-size flocs for CFP prepared with the same length of CF. CF was too long negatively affected paper formation, as the look-through index rose from 282 (2 mm CF) to 940 (8 mm CF). Either using polyethylene oxide as a disperser or reducing the CF concentration could reduce the look-through index of the CFP (2 mm CF) to below 200. The crowding factor of the CF suspension was suggested to be no more than 5. In addition, improvement in CFP formation led to higher tensile strength and lower air permeability in CFP. All these results are expected to prepare CFP with superior formation, thereby improving other properties of CFP.

Development and performance study of a natural silk fiber facial mask paper

Facial masks are beauty products which composed of a facial mask paper and beauty solution. Silk contains the amino acid structure closest to the human skin, and has the skin-friendly, cosmetic and antibacterial functions, but the common method for making nonwoven facial mask paper is not suitable for silk. In this paper, the silkworm’s spinning path is intervened manually to obtain a smart silk facial mask paper (SMC) of controllable thickness, so that the sericin on the silk fiber is well preserved. In the experiment where the SMC is compared with the nonwoven 384-cuprammonium rayon facial mask paper (CRMC) which is the most widely used in the market, it is found that the ways of forming the two facial mask paper are completely different, and therefore the morphologies under SEM are obviously different. The thickness of the SMC is 0.183 mm and the areal weight of it is 38.0 g/m2. It is very close to the CRMC (0.187 mm, 38.4 g/m2). The porosity of the SMC is 84.0%, which is slightly lower than that of the CRMC (86.3%), but its pores are well distributed. Compared with the CRMC, the smart SMC has higher dry and wet strength, lower elongation, slightly lower air permeability and liquid entrainment rate, and better antibacterial performance.

Influence of Optical Brightening Agent Concentration on Properties of Cotton Fabric Coated with Photochromic Microcapsules Using a Pad-Dry-Cure Process.

The weak photostability of photochromic dyes applied to textile substrates is one of the disadvantages of the broader use of photochromic dyes in the textile industry. Therefore, the influence of optical brightener concentration on both the photocoloration and photostability of cotton fabric coated with photochromic microcapsules using a pad-dry-cure process, as well as the physical-mechanical properties and colorfastness properties, were studied in this research. Coated samples were subjected to different tests according to valid EN ISO standards; namely mass per unit area, fabric stiffness, breaking force and elongation, air permeability, and different colorfastness properties (rubbing, domestic and commercial laundering, and light). Results showed that the coated fabric had higher mass per unit area, stiffness, breaking force and elongation and lower air permeability compared to uncoated fabric, irrespective of the padding bath composition. Coated fabric has better colorfastness to wet than dry rubbing. The colorfastness to washing decreases with the increased number of washing cycles. The use of optical brightener decreases the photocoloration of coated fabric and increases the photostability of coated fabric after the exposure of samples to a Xenotest apparatus for longer than 12 h.

Effects of High CaO Fly Ash and Sulfate Activator as a Finer Binder for Cementless Grouting Material.

The effects or high CaO fly ash and sulfate activator on cementless grouting material were investigated through Labiles Waterglass (LW) grouting applied at an actual construction field. Circulating fluidized bed combustion ash was used as CaO fly ash, and petro cokes desulfurization gypsum was used as sulfate activator. Cementless grouting material (CGM) could decrease the gel time by about 16.7% compared with ordinary Portland cement (OPC). This characteristic improved the average daily workload and construction period per meter by about 13.5% with CGM. Furthermore, when constructing 1000 holes of LW grouting, the construction time could be reduced by 19 days (20% of the total construction period of LW grouting). Meanwhile, CGM could increase the homogel strength by about 48.4% after 28 days compared with OPC. After X-ray diffraction analysis and scanning electron microscope analysis, CGM was found to produce cement hydrate by chemical reaction mechanism of high CaO fly ash and sulfate activator, even though cement was not used. The matrix structure properties of CGM and OPC specimens were similar, but CGM, with 134.3% fineness, exhibited higher compressive strength and lower air permeability than OPC. As a result, CGM could reduce the leakage length per square meter by 74.4% compared with OPC. Using CGM as a substitute for OPC in LW grouting in actual sites could be beneficial in terms of securing construction speed and durability, as well as reducing CO2 emissions due to reduction of OPC usage.

Enhancement of water resistance and antimicrobial properties of paper sheets by coating with shellac

The present study was focused on the effect of shellac as a natural polymer on the mechanical, physical, and antimicrobial properties of the paper sheets. The surface modification of paper sheets was carried out using different shellac solutions. The capability of the treated sheet to absorb water and to permit air follow was studied by Cobb test and air permeability, respectively. It was found that the treated sheet had little affinity for water and low air permeability. The change of sheet surface properties after modification was ascertained by scanning electron microscopy and Fourier Transform Infrared Spectrophotometer (FT-IR). The shellac treated paper sheet displayed improved mechanical properties when compared with untreated paper sheet. The shellac treated sheets exhibit efficient antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Consequently, the prepared paper sheet can be used as novel materials for packaging applications.

Prebiotic carbohydrates: Effect on physicochemical stability and solubility of algal oil nanoparticles

This study aimed at providing a novel approach for improving the physicochemical stability and solubility of algal oil nanocapsules through formation of electrostatic interactions and prebiotic carbohydrates systems composed of: octenyl-succinic anhydride (OSA) starch, OSA/inulin (IN), OSA/maltodextrin (MD), OSA/chitosan (CS), OSA/MD/IN, and OSA/CS/IN. IN, a functional prebiotic modifier, was found to significantly (p < 0.05) decrease emulsion viscosity and particle size, with OSA/CS/IN particles having significantly (p < 0.05) improved water solubility (4.96%) and wettability (749 s) compared to OSA/CS particles. Interestingly, OSA/CS/IN particles had the highest oxidative stability (three times that of bulk oil) and encapsulation efficiency (98.57%). OSA/CS/IN particles were also more hygroscopic than pure OSA particles. Furthermore, scanning electron microscopy (SEM) revealed OSA/CS/IN particles had less wrinkled, smoother surfaces, providing lower air permeability and better protection. Therefore, OSA/CS/IN, as a prebiotic encapsulation system, may lead to the value addition of algal oil.

A new finishing process of cotton fabric

Ecological and economic responsibilities have led to the search for alternative material applications in the textile sector as well as in all sectors. Sol-gel technology is one of these applications with advantages such as realization under low temperatures and enabling the desired product shape and format. In this study, the samples of 100% cotton fabric have been processed by using pigment printing technique with natural pumice, amorphous silica and colemanite materials and printing fixation process has been performed by using the sol gel coating method. The sol gel treatment has been carried out with basic catalyst according to the zeta potentials of the solid particulate materials used. After the new created process, surface morphologies, EDS point analysis and F-TIR analysis of all fabric samples have been performed. In addition, the properties such as strength, UV protection, air permeability, water permeability, abrasion resistance, flammability of all fabrics have been investigated. The results of surface analysis have proven that the chemical components of the natural materials are transferred to the fabric samples. It has been proven by the test results that all cotton fabric samples are given high strength, UV protection, flammability, high abrasion resistance and low air permeability. Interpretation of all the analysis and obtained test results has been also made statistically. According to the study results, ecofriendly process step has been created that allows low energy cost and low chemical usage under low temperatures

Electrospun cellulose acetate and poly(vinyl chloride) nanofiber mats containing silver nanoparticles for antifungi packaging

Nanofiber mats of poly(vinyl chloride) (PVC) and cellulose acetate (CA) encapsulated with silver (Ag) nanoparticles were fabricated via electrospinning for potential use as antimicrobial food packaging materials. 16 wt% PVC was prepared in 1:1 w/w tetrahydrofuran—N,N-dimethylformamide while 16 wt% CA was prepared in 3:2 (w/w) Acetone—N,N-dimethylformamide. Scanning electron microscopy analysis showed that thinner fibers could be electrospun from cellulose acetate as compared to poly(vinyl chloride) at the same solution concentrations with fiber diameters ranging from 70 to 130 nm for cellulose acetate and 180–340 nm for poly(vinyl chloride). Nanofiber diameter reduced with addition and increase of silver nanoparticles from 0 to 1 wt%. Due to the smaller cellulose acetate nanofiber diameter, its mats had lower air permeability rates. Tensile strength tests indicated that the nanofiber mats had marginal to good tensile strength values relative to film based packaging materials. Antimicrobial examination of the nanofiber mats against yeast and mould indicated that there was inhibited growth of the microorganisms on mats containing silver nanoparticles.

Effect of microfiber layers on acoustical absorptive properties of nonwoven fabrics

There are several types of sound absorptive materials, such as natural and synthetic fibers, acoustic mineral wool, acoustic polyester panels, acoustic foam, cotton batts, that reduce the acoustic energy of a sound wave as the wave passes through. In this work, the use of nonwoven materials made of cotton, polyester, and polypropylene fibers for the development of sound absorptive nonwoven materials has been investigated. Samples of different materials (cotton, cotton/polyester blend, polyester fibers needle punched, and polypropylene melt blown nonwoven) and multilayer structures were tested on the designed impedance tube. Acoustic absorption properties of the fiber assemblies were studied in the frequency region of 100–1500 Hz. The values of sound absorption coefficient for different samples indicated that polypropylene microfiber melt blown nonwoven sample displayed a good sound absorption behavior in the entire frequency range. The use of multilayer samples improves the sound absorption coefficient with the condition that one of the layers is a thin melt blown nonwoven layer. The formation of nonwoven absorbent material consisted of hybrid layers, significantly reduces the resultant average sound absorption coefficient, especially when the upper layer is made from finer fibers of melt blown nonwoven of low air permeability value, and in this case the improvement reaches 50%. The use of melt blown layers of fine fibers values of noise reduction coefficient may reach 0.8. The multilayer nonwoven sound absorber design should take into consideration specific noise reduction coefficient values, not the absolute ones, particularly when the weight of the absorber is playing a decisive role.

Insulating sheath system and energy efficiency of buildings

The article discusses the results of thermal imaging monitoring of building structures with and without insulation. Research and thermal and physical calculations showed that heat loss from the premises is determined by two groups of factors: surface loss depending on thermal conductivity, as well as vapor and air permeability of enclosing elements and heat loss at all types of joints, fasteners, etc. Thermal insulation with plate materials significantly reduces heat losses, but at the same time, heat flows through the joints between the heat-insulating plates and in the areas of their contact with other structures, necessitating the use of steam and waterproof windproof roll materials. The usage of elastic and thermoplastic materials in the insulation circuit allows minimizing heat loss at the joints between the heat-insulating elements and along the smooth surface of the wall due to the low air and vapor permeability of the material. In the systems of frame cottages, when used as a thermal insulation of rolled foam-polyethylene, it becomes possible to form a seamless insulating shell of a building. This is made possible by connecting individual sheets of polyethylene foam into a lock, followed by hot air welding. Seamless insulation systems are used both in the construction of cottages and in the construction of frame and frameless logistic facilities and housing and communal services.

Air permeability and bursting strength of weft-knitted fabrics from glass yarn. Part II: knit architecture effect

In this study; the effects of loop, skip, and tuck stitch types, and weft-inlay yarn, on air permeability and bursting strength of weft-knitted fabrics from glass yarn were revealed. Due to clockwise rotation of wales and their arrangement being one on top of the other, besides the dramatic shortening of fabrics after their removal from the machine; fabrics with tuck stitches exhibited the highest stitch density, fiber content, and the shortest loop length. This caused the lowest air permeability and the highest bursting strength. Contrary to expectations, weft-inlay yarn did not contribute to bursting strength as much as tuck stitch did. An overall negative correlation between air permeability and bursting strength was disrupted by structures with tuck stitches. While tuck stitches from cotton yarn increased air permeability and decreased bursting strength in previous studies; this study indicated that tuck stitches from glass yarn decreased air permeability and increased bursting strength.

Air permeability characterization of glass fiber nonwoven fabric for liquid composite molding applications

Due to tailorable and superior mechanical properties normalized by their density; the use of fiber reinforced polymers (aka composites) is increasing steadily. Nonwoven surfaces from randomly oriented glass fibers are commonly used reinforcement fabrics in composite industry, and their resin infusion and final composite performances are largely dictated by their porosity that is quantified by air permeability. This research dealt with air permeability characterization of nonwoven fabric from chopped and randomly oriented glass fibers. Number of layers and fabric test face direction were selected as product input variables, while pressure drop and test head area were selected as process input variables. Front and back faces of the fabric stacks with single, double and triple layers were subjected to air permeability test with test head areas of 20 and 30 cm2, and across a pressure drop of 100 and 200 Pa. As expected, multiple fabric layers exhibited lower air permeability. While test face of fabric and test head area did not affect the air permeability; measurements performed under 200 Pa pressure drop resulted in higher air permeability than that of 100 Pa at statistically significant level, which was explained by Bernoulli Equation.

Synthesis of silver nanoparticles using dialdehyde cellulose nanocrystal as a multi-functional agent and application to antibacterial paper

Development of a reliable and rapid process for synthesis of stable silver nanoparticles using nanocellulose is highly desired. In the present study, we report an efficient approach for the synthesis of stable silver nanoparticles (AgNPs) using dialdehyde cellulose nanocrystal (DACNC) as both reducing and stabilizing agent. The periodated cellulose nanocrystals (CNCs) were able to reduce silver ions to obtain cellulose nanocrystal–AgNPs (CNC–AgNPs) composites with high Ag percentage. The resulting composites were characterized by using UV–Vis spectroscopy, fourier infrared spectroscopy (FT-IR), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Furthermore, their antimicrobial activities were investigated. The formation of AgNPs was evidenced by the surface plasmon resonance peak at around 400 nm. XRD data showed diffraction peaks at 2θ 38.33o, 44.55o, 64.27o, 77.66o, which can be indexed to (111), (200), (220), (311), and (222) planes of pure silver, indicating the successful synthesis of silver nanoparticles. The TEM images of CNC–AgNPs showed spherical AgNPs with sizes from several nanometers to 30 nm on the cellulose nanocrystal surfaces. The composites showed high antibacterial activities against Escherichia coli and Staphylococcus aureus. When the CNC–AgNPs was added into the pulp fibers, the obtained handsheets also displayed strong antibacterial activities with higher strength properties and a lower air permeability, indicating potential applications in food packaging materials.

Predicting the heat transfer through protective clothing under exposure to hot water spray

Hot liquid splash hazard is a common risk in workplace safety from industrial to home scale, and thermal protective clothing is required to ensure workers' health and safety. In this study, an instrumented manikin test system was used to evaluate the protective performance provided by protective clothing against hot water spray. The effects of fabric properties on the protective performance were investigated, and empirical models were developed to characterize the relationships between fabric properties and thermal protection. The contribution of stored energy to skin burn was also explored. The results indicated that the water repellence finish significantly affected the heat transfer and the protective performance, while the fabric weight and density had slight effect on the protection. The garment with lower air permeability provided better thermal protection. The overall performance increased with the increasing of air gap size for permeable garments. The weft stiffness of the fabric affected the performance as well. The garment with lower stored energy during exposure (EAE) and cooling phase (CAE) provided better thermal protection. The lower the ratio of absorbed energy during exposure to absorbed energy when 2nd degree burn occurred, the higher the stored energy contribution to skin burn injury. Though fabric weight did not show main effect on heat transfer and skin burn injury in permeable garments, it did affect the EAE/BAE. The findings suggest effective design improvement for the protective clothing.

Design of novel running leggings with thermoplastic polyurethane membrane compression zones

Compression garments are widely used by athletes to improve athletic performance and to avoid potential injuries. Some compression garments are developed to exert pressure on muscle groups via thermoplastic polyurethane (TPU) membrane layers laminated on the textile surface. This study investigates the effect of novel TPU membrane patterns on muscle performance of the lower extremities and on the comfort parameters of air and water vapor permeability. Three novel running leggings with TPU membrane compression zones were designed to exert pressure on the major muscle groups used during running. Electromyography (EMG) measurements of the female participants wearing the designed leggings with TPU membranes, conventional leggings and shorts were recorded during a standardized squat protocol via a wireless surface EMG system. A repeated measures analysis of variance with a Greenhouse–Geisser correction determined that the mean root of mean square values for the EMG signals retrieved from the rectus femoris, vastus lateralis, gastrocnemius and hamstring muscles while wearing a specific legging design revealed statistically significant reductions in muscle activation. On the other hand, comfort tests exhibited low water vapor permeability and air permeability results when the textile surface was laminated with the TPU membrane. TPU membranes laminated on athletic wear to create compression zones could be effective in reducing muscle activation. Comfort performance is another essential design parameter that should be integrated into the design decisions. Large surfaces of solid TPU membranes should be minimized and surface textures should be employed for increased breathability.

Preliminary Experimental Investigation on the Strength and Air Permeability of Reactive Powder Concrete

A new reinforced concrete foundation system is being proposed to store renewable energy through the compressed air energy storage technology. For this application, the concrete is required to resist considerable tensile strength and to have low air permeability, which is not observed in normal concrete. Therefore, this paper is proposing to use reactive powder concrete for the suggested foundation system. Reactive powder concrete (RPC) is obtained by introducing either micro-cementitious materials like silica fume or fine powders like crushed quartz into the concrete mixture from where coarse aggregates had been removed. RPC has low water content and dense particle packing which lead to high strength and low air permeability characteristics. This paper conducts preliminary experimental investigations on the strength and air permeability of the RPC. Two important mix design parameters are studied including water-to-binder ratio ad silica fume content. Preliminary correlations between mix design parameters and strength/air permeability are developed. From the preliminary test results, it is concluded that the reactive powder concrete has potential to meet the high strength and low air permeability requirements, and is suitable for the proposed energy storage foundation system.

A Clothing Ventilation and Heat Loss Electric Circuit Model with Natural Convection for a Clothed Swinging Arm of a Walking Human

ABSTRACTThis work aims to develop a computationally effective electric circuit model to estimate the ventilation and heat transfer for walking human in the presence of natural convection. The ventilation circuit includes flow resistance, inductance, and electromotive force elements. It is coupled to an electric resistance circuit of heat flows to adjust the temperature difference inducing natural convection flow. The coupled ventilation and heat circuit models predicted both the segmental ventilation rate and heat loss from the arm at different walking and wind speeds. The developed model of the segmental ventilation and heat transfer from the clothed human segment was validated by performing experiments on a walking thermal manikin using tracer gas method. Good agreement was observed between the model predictions and the experiment at a maximum relative error of 10% lying within the standard deviation range. Results showed that the simplified ventilation-heat circuit models succeeded in estimating the natural convection effect at low computational cost. Moreover, it was shown that the effect of natural convection is more significant in walking at no wind than in windy condition. Accounting for natural convection effect increases the segmental ventilation and heat loss at low air permeability (0.02 m/s) by 68% and 20%, respectively.