Wicking Properties Research Articles

Dihydroxyacetone levels in electronic cigarettes: Wick temperature and toxin formation.

Recently, we reported the presence of dihydroxyacetone (DHA), the active ingredient in sunless tanners, in the aerosol of an electronic cigarette. DHA has been shown to react with DNA in vitro. The FDA restricts the use of DHA to external application only. It states that it should not be inhaled, ingested, or come into contact with any areas containing mucous membranes, due to unknown risk. Herein, the quantification of DHA in the aerosols of three brands of e-cigarettes has been carried out. These included two devices with horizontal heating coil configurations as well as one with a sub-ohm resistance vertical heating coil. In order to understand and begin to address the origin of DHA and related aerosol products, the wicking properties of the three e-cigarettes were compared. DHA levels were analyzed by a combination of GS/MS and 1H NMR. DHA was found in all three e-cigarettes, with substantially less in the sub-ohm, vertical coil device as compared to the horizontal coil devices (e.g., 0.088 μg/puff vs. 2.29 μg/puff, respectively). Correspondingly, the temperature of the wet layer of the wick for the vertical coil was relatively stable, compared to the wicks for the horizontal coils, upon increasing battery power output. This result is in agreement with prior studies of e-cigarette wicking efficiency and aerosol toxin formation. The temperature measurements reported are a simple means for comparing devices with different design properties during operation.

Effect of Bamboo Viscose on the Wicking and Moisture Management Properties of Gauze

Bamboo viscose or regenerated cellulose fibers were used to check their absorbency properties effect on the wicking and moisture management in gauzes. Bamboo viscose and cotton fibers were spun into five different yarn samples with different fiber proportion by ring spinning. Fifteen different gauze samples were made of these yarn samples. The gauze samples were subjected to wicking test to check the wicking ability. Water vapor transmission test was applied to check the vapor transmission rate. These tests were applied to measure the effectiveness of bamboo viscose, cotton and blended gauze samples in wound healing. Pure bamboo gauzes and gauzes with high content of bamboo fiber, i.e. 75B:25C and 50B:50C, shows better wicking and vapor transmission properties. It makes gauzes with high bamboo viscose suitable for wound care applications because of moisture absorbency.

Development of tri-layer knitted fabrics for shuttle badminton players

Thermo-physiological comfort of the fabric is attained through the ability of managing heat and transmission of sensible and insensible perspiration. An investigation on influence of tri-layer knitted structure on thermal comfort characteristics of layered knitted fabrics was carried out. Three tri-layer knitted structures were developed in which inner layer was made up of micro-fibre polyester and outer layer was made up of modal yarn. The yarn used in the middle layer was changed to either micro-fibre polyester or polyester or acrylic yarn. The thermal comfort characteristics such as thermal conductivity, air permeability, water vapour permeability, wicking, moisture absorbency, drying rate and moisture management properties have been analysed. Wear trial was conducted for shuttle badminton players and they were ranked using thermal environment subjective judgement scale. Tri-layer knitted structure with micro-fibre polyester in the inner and middle layer and modal in the outer layer showed better thermal comfort characteristics both by objective evaluation and wear trial method compared to polyester or acrylic in the middle layer and is preferable for shuttle badminton sportswear.

Preparation and characterization of polysulfone amide nanoyarns by the dynamic rotating electrospinning method

In this study, a novel electrospinning method and the related spinning device were developed to fabricate a new type of polysulfone amide yarn assembled with nanoscale fiber. The electrospun nanofibers extruded and stretched under the electric field force were assembled and twisted with a rotating receiver, so the freshly prepared nanofibers could be bundled into yarns continuously. The effects of solid concentration and the rotating speed of the collector on the yarn structures and properties were investigated systematically. The three-dimensional electric field was modeled and calculated theoretically to simulate the electric field distribution of the electrospinning system. The experimental results showed that the morphology, mechanical strength, and thermal and wicking properties were obviously affected by solid concentration and the rotating speed of the collector. It was found that the nanoyarn could achieve a better performance in morphology, strength, heat resistance, moisture absorption at 12 wt% and 40 r/min collector rotating speed. Therefore, the proposed advanced electrospinning technique in this paper could be used to produce multi-functional nanoyarns, which may be useful for the application of nanoyarns in various industrial fields.

Electrospun dual-layer mats with covalently bonded ZnO nanoparticles for moisture wicking and antibacterial textiles

The fast growing demand for advanced sportswear suitable for tropical countries has led to research on fabrics with both moisture wicking and anti-bacterial properties. In this work, to improve the water transport behaviour, dual-layer nanofibrous nonwoven mats composed of a hydrophilic polyacrylonitrile (PAN) outer layer and a hydrophobic poly(vinylidene fluoride) (PVDF) inner layer are fabricated by electrospinning. The distinct difference in surface hydrophobicity between the inner and outer layers induces a push-pull effect to transport water from the inner to the outer surface efficiently. To render an antibacterial property, zinc oxide (ZnO) nanoparticles are covalently attached to the PVDF nanofibers. The good anti-wash properties and anti-bacterial function of the ZnO-PDVF/PAN dual layer mats are demonstrated.

Optimization and surface modification of silk fabric using DBD air plasma for improving wicking properties

It is necessary to study the suitable effect of plasma parameters, such as exposure time and applied voltage on the wicking properties of silk fabrics. Wicking property of silk fabric has been improved by using air dielectric barrier discharge plasma treatment. The plasma treatment has been utilized to modify the surface properties of silk fabrics. Untreated and plasma-treated fabrics have been characterized by contact angle Goniometer, wicking test, Wet-out time, scanning electron microscope, Attenuated Total Reflection Fourier Transforms Infrared spectrometer (ATR-FTIR) and dye uptake test. The ATR-FTIR characterization shows that the hydroxyl functional group has been increased after plasma treatment of silk fabric. The experimental results of wicking rate and Wet-out time of the plasma-treated silk fabrics have shown significant improvement in hydrophilic properties that could be confirmed by contact angle measurement which is close to 0°. The tensile strength of untreated and plasma-treated fabrics has been measured to confirm the enhanced surface property.

의류소재용 직·편물의 수분이동 특성 측정 방법에 따른 흡한속건성 평가

의류소재용 직·편물의 수분이동 특성 측정 방법에 따른 흡한속건성 평가

Nanoceramic Enhanced, Block Copolymer Derived Nanoporous Battery Separators

A battery separator physically and electronically separates the anode and cathode but permits Li+ transport between them. Battery separators play a critical role in battery safety by providing, e.g., thermal shutdown functionality in abusive events, or, by preventing lithium metal dendrites or other defects in the cell from penetrating the membrane which can cause internal short circuit leading to uncontrolled thermal runaway, as in the case of the Boeing 787 battery fire incident [1]. One of the challenges with designing safe battery separators is the trade-off between mechanical robustness and porosity/transport properties. For example, high separator tortuosity is good for dendrite resistance but can lead to higher separator resistance [2]. Separator design is further complicated by additional constrains including tolerance to abuse conditions, stable at high voltages (e.g., > 4V), chemically inert to other cell materials, and low cost to meet the performance and cost targets. There is a need to tailor design battery separators that enable high energy and power with engineered functionality for safety, without adversely affecting cost. Here we present ADA efforts, in collaboration with university and industrial partners, to develop a highly tunable, nanoporous battery separator derived from functionalized block copolymers (polyolefins) with low cost precursors. Figure 1 shows scanning electron microscopy (SEM) images of the synthesized nanoporous polyethylene (NPE) membranes, an average 25 mm thickness, revealing the desired bicontinuous cubic morphology and percolating pore architecture. Our membranes possess a narrower pore size distribution and a high porosity, as intended based on our chemistry design selection, compared with the commercial separator. Figure 2 compares the electrolyte wicking property of a commercial and a nanoporous separator. The electrolyte is a Li-ion battery electrolyte consisting of 1M LiPF6 in a carbonate based solvent mixture. The nanoporous separator clearly shows much better wicking (absorbing) of the electrolyte, compared with the commercial counterpart. The electrolyte contact angles were estimated to be 31° for NPE and 69°for the commercial samples, respectively, consistent with the electrolyte wettability observation.Figure 3 shows charge/discharge voltage vs. specific capacity during formation for a commercial and NPE separator based Li/LiCoO2 (LCO) half cells, displaying characteristic LCO voltage profiles vs. Li/Li0. The NPE separator based cells delivered an equivalent (or slightly higher) specific capacity, compared to the control cells. This result is very encouraging and represents the first demonstration of this class of block polymer derived, high-density linear polyethylene based nanoporous separators in a real lithium battery chemistry. Figure 4 shows discharge capacity vs. cycle number for the commercial and NPE separator based graphite/LCO full cells. These cells were cycled at £ 1C rates. Excellent cycle life stability was observed for the NPE separator based full cells, overlapping closely with the commercial separator based full cells. Our study shows that the strategy of preparing block copolymer derived nanoporous separators provides a very promising and powerful tool to allow exquisite tuning of performance and safety features of the nanostructured separator for the next generation Li-ion batteries. References National Transportation Safety Board Incident Report, NTSB/AIR-14/01, PB2014-108867, Jan 7, 2013. Pankaj Arora and Zhengming (John) Zhang, Chem. Rev. 104, 4419-4462, (2004). Figure 1

Permeability and Wicking Properties of Modal and Lyocell Woven Fabrics Used for Clothing

In this study, air permeability, water vapor permeability and wicking properties of certain woven fabrics, which are important comfort properties for clothes and garments, have been investigated. The effects of raw material (modal, Lyocell), weave pattern (plain, 2/2 twill, 1/3 twill, 2/2 matt) and weft yarn density (18, 22, 26) on these properties have been analysed graphically and statistically. The comfort characteristics of fabrics (permeability and wicking properties) are closely associated with the changes in their structural parameters: 2/2 matt and plain woven fabrics, where porosities are high, have better permeability and wicking properties. Increasing weft yarn density lead to decreases in porosity, resulting in decreased permeability and wicking properties. Increasing yarn twist increased the porosity of the fabrics. Lyocell fabrics showed improved permeability and wicking properties over modal fabrics due to Lyocell fibers’ high percentage of fibrillary structure.

Thermophysiological comfort properties of polyester weft-knitted fabrics for sports T-shirt

In sportswear industry, the usage of synthetic material is increasing due to its excellent water transport characteristic. This study aims to evaluate the thermo-physiological comfort properties of different sports fabrics and to investigate the effect of fabric physical property and knitting parameter on comfort-related properties of commercial sportswear fabric. Vertical wicking test, wettability test, dry rate test as well as air resistance test were conducted on 17 types of polyester-knitted fabrics obtained from market. Analysis of variance and multiple-comparison least significant difference test was performed to select the best fabric for sportswear. A single jersey fabric sample No. 16 made of 75D/100f in 145 g/m2 as determined to be the best fabric for sports T-shirt due to its excellent wicking property, faster water absorbency, quicker dry rate, and lower air resistance. It is likely that finer filament, low fabric mass, and proper density are associated with best property. Besides, it is found that higher mass was associated with higher air resistance, higher porosity was associated with faster dry speed, and faster vertical wicking rate was associated with shorter water absorption time for fabrics tested in this study.

Highly Absorbent Antibacterial Hemostatic Dressing for Healing Severe Hemorrhagic Wounds.

To accelerate healing of severe hemorrhagic wounds, a novel highly absorbent hemostatic dressing composed of a Tencel®/absorbent-cotton/polylactic acid nonwoven base and chitosan/nanosilver antibacterial agent was fabricated by using a nonwoven processing technique and a freeze-drying technique. This study is the first to investigate the wicking and water-absorbing properties of a nonwoven base by measuring the vertical wicking height and water absorption ratio. Moreover, blood agglutination and hemostatic second tests were conducted to evaluate the hemostatic performance of the resultant wound dressing. The blending ratio of fibers, areal weight, punching density, and fiber orientation, all significantly influenced the vertical moisture wicking property. However, only the first two parameters markedly affected the water absorption ratio. After the nonwoven base absorbed blood, scanning electron microscope (SEM) observation showed that erythrocytes were trapped between the fibrin/clot network and nonwoven fibers when coagulation pathways were activated. Prothrombin time (PT) and activated partial thromboplastin time (APTT) blood agglutination of the resultant dressing decreased to 14.34 and 50.94 s, respectively. In the femoral artery of the rate bleeding model, hemostatic time was saved by 87.2% compared with that of cotton cloth. Therefore, the resultant antibacterial wound dressing demonstrated greater water and blood absorption, as well as hemostatic performance, than the commercially available cotton cloth, especially for healing severe hemorrhagic wounds.

Investigation on thermo-physiological and compression characteristics of weft-knitted 3D spacer fabrics

The thermo-physiological comfort and compression properties of knitted spacer fabrics have been evaluated by varying the different spacer fabric parameters. Air permeability and water vapor transmission of the fabrics were measured using the Textest FX-3300 air permeability tester and PERMETEST. Thermal behavior of fabrics was evaluated by (TCi) thermal conductivity analyzer and overall moisture management capacity was evaluated by moisture management tester. Spacer fabrics compression properties were also tested using KES-FB3. In the KES testing, the compression resilience, work of compression, linearity of compression, and other parameters were calculated from the pressure–thickness curves. Analysis of variance was performed using new statistical software named QC expert trylobite and Darwin in order to compare the influence of different fabric parameters on thermo-physiological and compression behavior of samples. This study established that the raw materials, type of spacer yarn, density, thickness, and tightness of surface layer have significant influence on both thermal conductivity and work of compression in spacer fabrics. The parameter which mainly influences the water vapor permeability of these fabrics is the property of raw material i.e. the wetting and wicking properties of fibers. The Pearson correlation between moisture capacity of the fabrics and water vapor permeability was found.

Wicking Enhancement in Three-Dimensional Hierarchical Nanostructures.

Wicking, the absorption of liquid into narrow spaces without the assistance of external forces, has drawn much attention due to its potential applications in many engineering fields. Increasing surface roughness using micro/nanostructures can improve capillary action to enhance wicking. However, reducing the structure length scale can also result in significant viscous forces to impede wicking. In this work, we demonstrate enhanced wicking dynamics by using nanostructures with three-dimensional (3D) hierarchical features to increase the surface area while mitigating the obstruction of liquid flow. The proposed structures were engineered using a combination of interference lithography and hydrothermal synthesis of ZnO nanowires, where structures at two length scales were independently designed to control wicking behavior. The fabricated hierarchical 3D structures were tested for water and ethanol wicking properties, demonstrating improved wicking dynamics with intermediate nanowire lengths. The experimental data agree with the derived fluid model based on the balance of capillary and vicious forces. The hierarchical wicking structures can be potentially used in applications in water harvesting surfaces, microfluidics, and integrated heat exchangers.

A numerical comparative study of the effect of working fluids and wick properties on the performance of capillary pumped loop with a flat evaporator

This study presents a numerical analysis of a capillary pumped loop (CPL) performance using different working fluids and porous wick properties. A complete CPL model is used, which describes the growth of the vapor pocket inside the porous wick. The CPL behavior is studied for different working liquids, such as methanol, acetone and ethanol. Results show that methanol is the most efficient fluid in terms of thermal conductance and heat transport capacity. The present work allows also to evaluate the importance of the wick properties in the improvement of the thermal characteristics for capillary pumped loop.

A multi-scale simulation method for the prediction of edge wicking in multi-ply paperboard

When liquid packaging board is made aseptic in the filling machine the unsealed edges of the board are exposed to a mixture of water and hydrogen peroxide. A high level of liquid penetration may lead to aesthetic as well as functional defects. To be able to make a priori predictions of the edge wicking properties of a certain paperboard material is therefore of great interest to the paper industry as well as to packaging manufacturers. In this paper an extended multi-scale model of edge wicking in multi-ply paperboard is presented. The geometric and physical properties of the paperboard are modeled on the micro-scale, and include fillers and fines. The absolute air permeabilities and pore size distributions are validated with experimental and tomographic values. On the macro-scale random porosity and sizing distributions, time and sizing dependent contact angles, and inter-ply dependence are modeled. Arbitrary shapes of the paperboard are handled through an unstructured 3D surface mesh. Stationary and transient edge wicking simulations are validated against experiments with excellent agreement. The simulations show that the diffusive menisci between the liquid and air phases together with the two-ply model is necessary to achieve good agreement with the transient edge wicking experiments.

Application of Sericin on Polyester Fabric

Sericin is a natural protein which is removed from silk in a process called degumming. In India, 250-300 tons of sericin is extracted per year and goes as waste, it has wide range of application because of its properties like antioxidant, antibacterial, UV resistant, anticoagulant and moisture retention capacity. This paper is concerned with the application of sericin on polyester fabrics using cross linking agents like di-methylol di-hydroxy ethylene urea (DMDHEU) and glutaraldehyde. The Polyester fabrics are pretreated with sodium hydroxide (NaOH) and low temperature plasma (Oxygen gas). This pretreated sericin applied polyester fabrics show the better improvement in the wicking (moistureabsorbency) and good dye uptake properties on acid dyed fabric and it will be used for medical application.

Characterizing the transplanar and in-plane water transport properties of fabrics under different sweat rate: Forced Flow Water Transport Tester.

The water absorption and transport properties of fabrics are critical to wear comfort, especially for sportswear and protective clothing. A new testing apparatus, namely Forced Flow Water Transport Tester (FFWTT), was developed for characterizing the transplanar and in-plane wicking properties of fabrics based on gravimetric and image analysis technique. The uniqueness of this instrument is that the rate of water supply is adjustable to simulate varying sweat rates with reference to the specific end-use conditions ranging from sitting, walking, running to other strenuous activities. This instrument is versatile in terms of the types of fabrics that can be tested. Twenty four types of fabrics with varying constructions and surface finishes were tested. The results showed that FFWTT was highly sensitive and reproducible in differentiating these fabrics and it suggests that water absorption and transport properties of fabrics are sweat rate-dependent. Additionally, two graphic methods were proposed to map the direction of liquid transport and its relation to skin wetness, which provides easy and direct comparison among different fabrics. Correlation analysis showed that FFWTT results have strong correlation with subjective wetness sensation, implying validity and usefulness of the instrument.

Low-temperature dyeing of silk fabric using atmospheric pressure helium/nitrogen plasma

Silk fabric was plasma treated in an indigenously developed atmospheric pressure plasma reactor in the presence of helium and nitrogen (He/N2) gaseous mixture at a discharge voltage of 5 kV and frequency of 21–23 kHz. The samples were plasma treated for 1 to 10 min with a constant nitrogen flow of 50 ml/min. They were also plasma treated in varying nitrogen flow rates in the range of 33.3 to 225 ml/min, keeping a constant helium (He) flow rate at 450 ml/min. The effects of plasma treatment time and nitrogen (N2) gas flow rates on water wicking, physical and chemical properties of the fabric surface along with rate of dyeing were investigated in details. The formation of amine groups in the plasma treated samples helps in faster exhaustion of acid dye even at a lower temperature. It was possible to dye the plasma treated silk fabric at 40 oC temperature instead of 90 oC, as is used conventionally. Due to higher dye exhaustion, the plasma treated sample showed a deeper shade. The physical and chemical properties of the samples were analyzed using SEM, ATR-FTIR, secondary ion mass spectrometer (SIMS), and XRD. Results indicate that water took only 408 s and 309 s to travel up to a height of 6 cm in the plasma treated samples for 4 min and 10 min, respectively. This was much shorter as compared to 696 s observed in the untreated (control) sample. The effects of plasma treatment time and the amount of nitrogen (N2) gas flow had a similar effect on water wicking. The plasma treatment time and N2 gas flow rates showed only marginal effects on mechanical properties of silk.

The Study of PTFE Wicks Application to Loop Heat Pipes with Flat Evaporator

This study investigates the application of PTFE wicks to flat-plate loop heat pipes (FLHPs). PTFE’s low heat transfer coefficient effectively prevents heat-leakage, which is a problem with using metal wicks, lowering the operating temperature and pressure. This paper uses PTFE particles to form wicks, and the effect of PTFE on flat-plate LHP performance is investigated. Experimental results shows that the highest heat load reached was 100W, with lowest thermal resistance of 0.61°C/W, and heat flux of about 10W/cm2, For the wick properties, the wick had an effective pore radius of the wick was around 9.2μm, porosity of 47%, and permeability of 1.0 x 10-12m2. Compared to the highest heat flux reported in literature thus far for PTFE flat-plate LHPs, the heat flux in this study was enhanced by around 50%.

Characterizing the transplanar and in-plane water transport of textiles with gravimetric and image analysis technique: Spontaneous Uptake Water Transport Tester.

Water absorption and transport property of textiles is important since it affects wear comfort, efficiency of treatment and functionality of product. This paper introduces an accurate and reliable measurement tester, which is based on gravimetric and image analysis technique, for characterising the transplanar and in-plane wicking property of fabrics. The uniqueness of this instrument is that it is able to directly measure the water absorption amount in real-time, monitor the direction of water transport and estimate the amount of water left on skin when sweating. Throughout the experiment, water supply is continuous which simulates profuse sweating. Testing automation could even minimise variation caused by subjective manipulation, thus enhancing testing accuracy. This instrument is versatile in terms of the fabrics could be tested. A series of shirting fabrics made by different fabric structure and yarn were investigated and the results show that the proposed method has high sensitivity in differentiating fabrics with varying geometrical differences. Fabrics with known hydrophobicity were additionally tested to examine the sensitivity of the instrument. This instrument also demonstrates the flexibility to test on high performance moisture management fabrics and these fabrics were found to have excellent transplanar and in-plane wicking properties.