Improving heat-retaining property of cotton fabrics through surface coatings

Regulating thermal conductivity of fabrics through surface coating is of practical importance. This work shows that a thin layer of polymer containing thermal insulating fillers can considerably increase the thermal insulating property of the fabric. Three commonly used thermal insulating materials, aluminum oxide (Al₂O₃), zirconium oxide (ZrO₂), and fumed silica, were used as filler. When they were dispersed separately in a polymer solution and applied to cotton fabric, the fabric showed decrease in thermal conductivity by 19.1–44.5% (based on pure cotton fabric). Marsh cooling method was used for the measurement of thermal insulation feature. The heating/cooling behavior of the fabrics was characterized by infrared thermography. The effects of the coatings on air permeability, surface wettability, color appearance, and flexural rigidity were also studied. The highest reduction in air permeability was 87.4% for the fumed silica-containing coating. Aluminum oxide coating increased the hydrophilicity of the cotton fabric while fumed silica coatings made the fabric surface hydrophobic. All coatings diluted the color of the fabric and changed it to paler one. Flexural rigidity of the fabric was increased in the order of ZrO₂ > Al₂O₃ > fumed silica.     

聚丙烯腈基活性碳纤维及其应用

活性碳纤维(ACF)是一种多孔材料,它可以通过物理或化学的方式从液体或气体中吸附多种成分,因此被用于许多应用中,特别是污染气体的净化、有毒气体的吸收、气体的分离、空调的除臭和水的净化等,ACF还可应用于医药领域。活性碳的另一种类粒状活性碳(GAC)同样可应用于以上各领域。尽管ACF的价格很高,但ACF的使用却更为广泛,这主要是因为其蓬松度大、孔径均匀,使它的吸收量和传质系数比粒状活性碳高12～15倍。原材料性能及碳化与活化工艺影响最终ACF的微孔数量和总表面积。由聚丙烯腈(PAN)原丝制得的ACF有着独特的吸收性能和相当高的强度。     

Effect of surface modification and knife penetration angle on the Quasi-Static Knife Penetration Resistance of para-aramid fabrics

The focus of this paper is to describe the effect of change in surface friction of single layer para-aramid (Twaron^®) square woven fabric and change in knife penetration angle on its Quasi-Static Knife Penetration Resistance (QSKPR). The surface friction of fabric was changed by depositing SiO₂ on its surface by using water glass as a precursor. Six different knife penetration angles (0°, 22.5°, 45°, 67.5°, 90° and 135°) were selected. Untreated and treated fabric samples were compared for change in QSKPR. It was observed that the deposition of SiO₂ on the surface of Twaron^® fabric increased the surface friction which resulted in the increase in QSKPR. The response of fabric against QSKPR changed from partial yarn cutting to individual yarn cutting in fewer steps and load was distributed to a larger area due to decrease in yarn slippage. The change in penetration angle changed the distance, knife cutting edge travelled to cut each next yarn(s) and when this distance increased, the QSKPR was reduced. The post-penetration image analysis of damaged fibres showed that the load distribution among warp and weft yarns was complementary and change in penetration angles changed the distribution of stabbing load among the warp and weft yarns. When yarns with higher tensile strength and less slippage were loaded, the fabric showed highest resistance to penetration. A QSKPR prediction model was also proposed at the end.     

Removal of methylene blue from aqueous media using activated carbon web

Activated carbon web is prepared by controlled pyrolysis of acrylic fibrous waste under the layer of charcoal using physical activation in high-temperature furnace. The carbonization was carried out at 1200 °C under different heating rate (i.e. 150 to 450 °C h^?1) with different holding time (i.e. 0 to 60 min) to decide optimum pyrolysis parameters. The heating rate of 300 °C h^?1 with no holding time revealed higher specific surface area of 280 m² g^?1. The prepared activated carbon web was later employed as adsorbent for removal of methylene blue from aqueous media. The effect of initial dye concentration, adsorbent dosage, stirring speed, and pH of solution was studied. The obtained results were later compared with adsorption isotherms (i.e. Langmuir and Freundlich). The Freundlich model was found to fit closely with results due to heterogeneous adsorption of dye molecules. Finally, virgin activated carbon and dye adsorbed activated carbon were tested for desorption behavior using differential scanning calorimetry and thermo gravimetric analysis. The significant reduction in desorption enthalpy from 172.46 to 52.43 J g^?1 is attributed to less adsorption energies of dye molecules on the surface of activated carbon due to nonhomogeneous distribution of active sites.     

Cooling effect of MWCNT-containing composite coatings on cotton fabrics

Multiwalled carbon nanotubes (MWCNTs) were dispersed in an aqueous solution of epichlohydrin based resin with the aid of a surfactant. The MWCNT-resin solutions were applied onto cotton fabrics to form a thin coating with different MWCNT contents (0, 11.1, 20.0, 33.3, and 50%). The thermal conductivity of the fabrics was measured based on the Newton’s law of cooling. The coating containing 50% MWCNTs showed 151% increase in the thermal conductivity. Infrared thermography was used to characterize the heating/cooling behavior of the fabrics. On contact with a 50°C hot surface, coated fabric that had 50% MWCNTs in the coating layer showed a 3.9°C lower equilibrium surface temperature than the untreated fabric. The cooling rate increased with increasing the MWCNT content within the coating layer. Such an effective cooling performance was attributed to the increased thermal conductivity and surface emissivity of the MWCNT-containing coating layer. The coating showed little influence on water contact angle of the coated fabrics, but slightly decreased the air permeability.     

组织结构对纺织品用作细胞固定化载体的影响

细胞固定化技术是生物工程中研究热点之一,纺织品在用作细胞固定化载体方面具有极大的潜力。设计并织造了几种不同组织结构的织物,通过比较不同组织结构的织物载体对细胞的吸附量和吸附稳定性,考察了在细胞固定化过程中纺织品载体的结构特征对其吸附行为的影响。研究表明,在细胞固定化过程中,织物载体的组织结构特征对细胞吸附量和吸附稳定性有显著影响;织物载体对细胞的固定化不同与对小分子物质的吸附,除了比表面积和孔径因素外,细胞本身的特性对固定化效果也有影响。     

Waterproof and moisture permeable coating of polyester fabrics using a novel waterborne polyurethane agent modified with silk fibroin and polyvinylpyrrolidone

A novel waterproof and moisture-permeable coating agent was prepared by modifying a waterborne polyurethane (WPU) agent with silk fibroin (SF) and polyvinylpyrrolidone (PVP), and the PVP/SF/WPU blended agent was applied in polyester fabric coating to achieve a desirable waterproof and breathable effect. The PVP/SF/WPU film prepared by the novel coating agent was characterized with Fourier transform infrared (FT-IR), scanning electron microscope (SEM), thermogravimetry (TG) and X-ray diffraction (XRD) techniques, and the moisture permeability and water repellency of the PVP/SF/WPU coated polyester fabrics were evaluated. The results showed that the thermostability of the blended film was increased compared to the single WPU film, and the compatibility of SF and polyurethane was improved with adding PVP component; the moisture permeability and waterproof of the PVP/SF/WPU coated polyester fabrics were improved significantly. The optimized recipe of the PVP/SF/WPU-coating agent was as follows: 10 wt.%SF (with particle size of 5 μm), 4 wt.% PVP, 4 wt.% cross-linking agent TF694A, and 2 wt.% Thickener TF601. The water vapor transmission rate and hydrostatic pressure value of the PVP/SF/WPU coated polyester fabric reached 5,031 g/ (m² 24 h) and 493 mm H₂O, respectively. The physical and mechanical properties of the coated fabric were not considerably affected.     

Preparation of polypyrrole coated cotton conductive fabrics

Polypyrrole-coated cotton conductive fabrics were prepared by in situ polymerization. The influences of pyrrole dosage, mole ratio of pyrrole to iron (III) chloride, reaction temperature and reaction time on the conductivity of the polypyrrole-coated cotton conductive fabrics were analyzed. The best method for preparing the polypyrrole-coated cotton conductive fabrics was determined. The structures of the conductive cotton fabrics were characterized with Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that when mo1e ratio of pyrrole to iron (III) chloride was 2:1, reaction at room temperature for 1 h with a bath ratio of 1:40, the conductivity of the prepared fabric was the best with a surface resistance of 0.15 kΩ/cm. The chemical structure and the surface morphological structures of the conductive cotton fabrics were different from that of the untreated cotton fabrics. By in situ polymerization, the fiber surfaces appeared homogeneously coated with a film of polypyrrole. Importantly, the process of pyrrole polymerization is very simple. This study offers a new simple way for preparing the polypyrrole-coated cotton conductive fabrics effectively.     

Modeling effective diffusivity of volatile organic compounds in activated carbon fiber

Volatile organic compounds (VOCs) comprise 67% of total hazardous air pollutants (HAPs) that are emitted by major industrial point sources into the U.S. atmosphere (1). Adsorption by activated carbon fiber (ACF) has been recognized as one of the feasible regenerative control processes to separate and recover VOCs for reuse. Characteristics of VOCs transport in ACFs are required to efficiently design ACF sorption systems. However, extensive resources are spent experimentally obtaining transient sorption data to design adsorption systems. As an alternative, this work develops a new model that predicts effective diffusivities of VOCs into ACFs. The diffusion process is modeled as Knudsen transport into the ACF open pore spaces coupled with activated surface diffusion on the ACF's internal surface area. Temperature and Darken's factors are included in the surface diffusion model to provide corrections for thermodynamic state and deviation from Fick's Law, respectively. Depth of the adsorption potential well is considered as the product of the heat of adsorption of a reference VOC, an adsorption similarity factor, and a surface diffusion energy factor. Introduction of the adsorption similarity factor in the effective diffusivity model is a new concept providing a means to predict effective diffusivity of similar adsorption systems from a reference system. Experimental data from a short length column are used to determine effective diffusivity of acetone in ACF. Results from this diffusivity model are compared to experimental values for the acetone/ACF system to describe the degree of closure between modeled and experimental results.     

Electromagnetic shielding effectiveness of carbon/stainless steel/polypropylene hybrid yarn-based knitted fabrics and their composites

In this study, a range of conductive hybrid knitted fabrics and their composites have been investigated for shielding effectiveness in the frequency ranges of 50 MHz to 1.5 GHz (low frequency) and 4 to 8 GHz (C-Band). Carbon and stainless steel (SS) filaments were combined in Dref-3 spinning machine and different hybrid yarns were prepared. The plain- and rib-knitted fabrics were made in V-bed flat knitting machine from the prepared hybrid yarns. The composite laminate was prepared by sandwiching a ply of fabric between the polypropylene films in compression moulding machine at 180 °C for 5 min under a consolidation pressure of 12 bar. All the fabrics and composites were tested for shielding effectiveness (SE) in coaxial transmission line and C-band waveguide with the help of vector network analyser. It was observed that fabric having both conductive loop and inlaid yarns exhibited higher SE of 20.2 dB than other fabrics in low-frequency range. However, in the composite form, carbon composite with SS inlaid yarn showed better SE of 45 dB than other composites. In C-band frequency range, conductive loop fabric structures yielded high shielding effect in course direction compared to wales direction. Compared to fabric form, the composite showed higher SE for all frequency ranges. This study proposes that knitted fabrics and their composites can be utilized as electromagnetic shields in wide frequency ranges.     

负载金属改性活性碳纤维材料制备及吸碘性能

以活性碳纤维（ACF）为原料,采用浸渍法制备了负载金属银的改性活性碳纤维（Ag-ACF）,并通过测定吸附材料在77 K的氮气吸附等温线对改性前后材料的比表面积和孔结构进行了表征.研究并比较了活性碳纤维在负载金属银后对碘的吸附性能,结果表明,在活性碳纤维上负载适量的金属银,可以显著地提高活性碳纤维对碘的吸附容量,原因是由于金属银对活性碳纤维比表面积和表面化学性质的修饰,并提高了活性碳纤维对碘的吸附势.     

Approaches to mitigate the impact of dissolved organic matter on the adsorption of synthetic organic contaminants by porous carbonaceous sorbents

Adsorption of trichloroethylene (TCE) and atrazine, two synthetic organic contaminants (SOCs) having different optimum adsorption pore regions, by four activated carbons and an activated carbon fiber (ACF) was examined. The selected adsorbents had a wide range of pore size distributions but similar surface acidity and hydrophobicity. Single solute and preloading (with a dissolved organic matter (DOM)) isotherms were performed. Single solute adsorption results showed that (i) the adsorbents having higher amounts of pores with sizes about the dimensions of the adsorbate molecules exhibited higher uptakes, (ii) there were some pore structure characteristics, which were not completely captured by pore size distribution analysis, that also affected the adsorption, and (iii) the BET surface area and total pore volume were not the primary factors controlling the adsorption of SOCs. The preloading isotherm results showed that for TCE adsorbing primarily in pores < 10 angstroms, the highly microporous ACF and GACs, acting like molecular sieves, exhibited the highest uptakes. For atrazine with an optimum adsorption pore region of 10-20 angstroms, which overlaps with the adsorption region of some DOM components, the GACs with a broad pore size distribution and high pore volumes in the 10-20 angstroms region had the least impact of DOM on the adsorption.     

Facial preparation of superhydrophobic and superoleophilic textiles by depositing nano-SiO2 for oil–water separation

In this study, a facile one-step dip-coating approach was reported for the fabrication of superhydrophobic and superoleophilic cotton fabrics for oil–water separation. By depositing the hydrophobic nano-SiO₂ on the micro-scale cotton fabric surface, the combination of the nano-SiO₂ and the micro-roughness cotton fabric created a micro/nano-binary surface roughness and presents superhydrophobicity and superoleophilicity. SEM, EDS, and TGA result shows that the treated cotton fabric was completely covered by the nano-SiO₂ particles when the nano-SiO₂ particles was about only 3.6 wt% of the pristine cotton fabric. The separation efficiency of the fabricated superhydrophobic and superoleophilic fabric was calculated up to 98.3 wt%. The one-step production technique described here is realizable for industrial use, relatively mild processing conditions, and large-scale fabrication.     

Cotton fabric dyeability assessment of floral extracts obtained from binary mixtures of Callistemon citrinus and Tagetes erecta L

Parameters affecting extraction of natural colorants from five binary mixtures of floral parts of Callistemon citrinus and Tagetes erecta L., like ratio of each flower in the binary mixture of powdered floral parts, amount of powdered binary mixture to liquor ratio and extraction time, were optimized for dyeing of cotton fabric. Optimum dyeing was obtained at 60°C with 70 g/L exhausting agent (Na₂SO₄), material to liquor ratio of 1:50 along with dyeing time of 100 min. The dyed fabric revealed good anti-bacterial activity and excellent ultraviolet protection factor (UPF).     

Patulin Adsorption Kinetics on Activated Carbon, Activation Energy and Heat of Adsorption

The kinetics of adsorption of patulin on activated carbon were studied at different initial patulin concentrations (100–400 ppb) for the temperature range 20–80°C. Apparent adsorption rate constants (k_aapp) were changed from 1.07 × 10^?3 to 1.86 × 10^?3 g^?1 min^?1 while the temperature increased from 20 to 80°C. For equilibrium adsorption curves; the Langmuir model was attempted and model parameters (K and Q°) were obtained for different temperatures. Energy of activation and heat of adsorption were determined in a batch adsorption system (E_a= 2.02 kcal/mol and ΔH = 2.24 kcal/mol). The adsorption occurred endothermically and by physical mechanisms.     

Inactivation Kinetics of the Most Baro-Resistant Enzyme in High Pressure Processed Litchi-Based Mixed Fruit Beverage

This work focused on a litchi-based mixed fruit beverage, comprising of coconut water and lemon juice, mixed in an optimized proportion. Based on preliminary studies, three resistant spoilage enzymes were identified in the beverage, viz. polyphenol oxidase (PPO), peroxidase (POD), and pectin methyl esterase (PME). The response surface methodology (RSM) based on central composite face-centered design (FCCD) screened out PPO as the most resistant enzyme within the high pressure processing (HPP) domain of 200–600 MPa/30–70 °C/0–20 min. A detailed kinetic study was conducted on PPO inactivation within the same HPP domain along with a set of thermal treatments (0.1 MPa/30–70 °C). A synergistic effect of pressure and temperature on PPO inactivation was observed, throughout the HPP domain. However, PPO was almost completely inactivated at 500 MPa/70 °C/20 min. The inactivation order (n) values for PPO were 1.10 and 1.25 for thermal and HPP treatments, respectively. For every 10 °C rise in temperature, the inactivation rate constant (k, U^n-1 min^?1) increased approximately by 1.5 times, within 50–70 °C (at 0.1 MPa), while a 10-fold increase was obtained in the case of HPP treatments. The activation energy (E _a ) and the activation volume (V _a), depicting the temperature and pressure dependence of k, was found to decrease slightly, with an increase in pressure and temperature, respectively. The PPO inactivation rate constant was modeled as a function of both temperature and pressure conditions by combining both Arrhenius and Eyring equations.     

Optimization of low temperature bleaching of cotton using statistical modelling

Very high temperatures (e.g. ~98 °C) are mainly used to perform hydrogen peroxide (H₂O₂) bleaching of cotton fabrics in industrial practice. Such harsh conditions can lead to high fabric damages and high energy consumptions. In recent years, an extensive research is being done to reduce the temperature for industrial cotton bleaching process. Similar attempt has been made in the present work, where the synthesized polyamidoamine dendrimers have been used as a stabilizer in the place of sodium silicate. The low temperature bleaching was optimized using a statistical model. An optimized recipe was formulated based on the half factorial central composite design and numerical optimization solution by Design-Expert 6.0 software. The performance of the optimized sample was compared with the sample using traditional method of bleaching and achieved the lower bleaching temperature of 70–80 °C than the traditional bleaching temperature with fabric’s whiteness index comparable.     

Enhanced magnetic and antifungal characteristics on wool with Fe3O4 nanoparticles and BTCA: a facile synthesis and RSM optimization

A facile route for the synthesis of high-quality Fe₃O₄ nanoparticles (FNPs) has been successfully confirmed by employing a co-precipitation technique and then was stabilized onto wool fabric through a simple “impregnating” process. Here, the synergistic effect of BTCA and synthesized FNPs on magnetic and antifungal characteristics of the wool fabric was investigated. The FNPs was stabilized on the wool surface using BTCA cross-linking agent. The role of both FNPs and BTCA concentrations on magnetic and antifungal properties of samples was optimized using response surface methodology. The magnetization properties and uniform distribution of FNPs on the wool surface were characterized by vibrating sample magnetometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The saturation magnetization and antifungal activity against Candida albicans of BTCA/FNPs-optimized wool was 7.8 emu g^?1 and 98.31%, respectively. Subsequently, treated wool fabric with optimum concentration of FNPs and BTCA enhanced magnetic and antifungal properties.     

Filtration efficiency investigation of mesh fabrics by polytetrafluoroethylene filament with surface static electricity

Particulate matter (PM) pollution has become a severe environmental problem. The application of some static electric materials with high filtration efficiency became more and more popular. However, the escape of surface voltage was unbeneficial to the long-term application of this material. Herein, this research reported novel static electric materials polytetrafluoroethylene (PTFE) and tourmaline. With the application of these two materials, a kind of fabric with high surface electricity, filtration efficiency, long-term stability and low pressure drop was exploited. This fabric was woven by PTFE filaments containing tourmaline particles of four different content and particle size. By means of the surface electricity and filtration efficiency measurement, the fabric containing 7 wt % tourmaline particles possessed the largest surface electricity of 830 V, as well as highest filtration efficiency of 75.6%. In addition, a model of electric field distribution in filament and fabrics were both proposed by the static electricity test to interpret the mechanism of filtration. The successful fabrication of such an intriguing material might provide a new application for the electret materials for PM removing.     

Heat-treated wood as chromium adsorption material

Heavy metals adsorption with lignocellulosic materials has been heavily researched in the last years. Since heat activation has been used with good results to increase the adsorption capacity of some materials, heat-treated wood might be a better adsorbent. This hypothesis is the basis of the present study. The adsorption tests were made with powdered pine wood, heat-treated at 190–210?°C. All the heat-treated samples showed a significantly higher adsorption compared to untreated wood. The maximum adsorption was obtained at pH 3 for heat-treated wood at 210?°C. The kinetics of the adsorption process fitted a pseudo-second-order reaction (R² 0.990–0.996). Adsorption fitted well both the Langmuir and the Freundlich model, but the Freundlich model presented higher R² (0.988–0.998). The q_max values estimated by the Langmuir plotting were in the range 15.6–19.4 mg/g and the n values from Freundlich isotherms between 1.87 and 2.39. Heat-treated wood was a better adsorption material than untreated wood for chromium adsorption. This can be a good application for the sawdust produced by the processing of heat-treated wood at primary and secondary wood processing mills or for the recycling of heat-treated wood at the end of product life.