Uncoated Fabric Research Articles

Enhancement of Thermal Stability, Flame Retardancy, and Antimicrobial Properties of Cotton Fabrics Functionalized by Inorganic Nanocomposites

In this investigation, various metal oxide (ZrO2, MgO, TiO2) nanoparticles were prepared using the hot-air spray pyrolysis method. The prepared nanoparticles were characterized using the X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and transmission electron microscopy. The colloidal silica (SiO2) sol was prepared using the sol–gel method, mixed with various metal oxides (ZrO2, MgO, TiO2). Uncoated cotton fabrics were separately impregnated with the prepared nano(composite) sols followed by the pad-dry-cure method. The structural analysis of the coated and uncoated fabrics was performed using XRD. The surface morphology of the coated and uncoated cotton fabrics was analyzed using SEM. The elemental analysis using energy-dispersive spectroscopy confirmed the presence of nanoparticles along with cellulose on the surface of the fabric. The thermal stability and flame retardancy properties and residue of the coated and uncoated fabrics were studied. The coated cotton fabrics showed be...

Development of functional hybrid cotton fabrics by coating with SiO2and ZrO2/SiO2composites

The silica (SiO2) sol and hybrid zirconia (ZrO2)/SiO2 sol were used to coat cotton fabrics using the pad-dry-cure method to improve their physical and functional properties. The physical properties of coated and uncoated fabrics, such as tensile strength, tear strength, crease recovery angle, air permeability and whiteness index, were tested as per the standard test methods. The wash durability of the coating on the fabric was also analysed after five and 10 wash cycles. The observed results show that the ZrO2/SiO2-coated fabric has better physical properties than SiO2-coated and uncoated fabrics. In addition, an antibacterial activity test confirms that the SiO2-coated fabric possesses higher antibacterial properties against Escherichia coli and Staphylococcus aureus than the ZrO2/SiO2-coated fabrics.

Preparation and characterization of multifunctional cotton fabric by coating with sonochemically synthesized zinc oxide nanoparticle-flakes and a novel approach to monitor its self-cleaning property

Multifunctional cotton fabric has been prepared by pad-dry-coating with sonochemically synthesized zinc oxide nanoparticles. The uniqueness of sonochemical synthesis is that it synthesizes without alkali at near neutral pH and hence the cotton fabric is exposed to less chemical stress. As a result of coating, the fabric shows enhanced mechanical strength, water and stain repellence, antimicrobial properties, UV-blocking capacity and self-cleaning characteristics compared to the uncoated fabric. The self-cleaning property was tested with Trypan Blue dye under sunlight. The attempt of quantifying the self-cleaning process with the rate of decolorization is a novel one. It was observed that about 69% of the colour was removed when the coated fabric was exposed to sunlight for 3 h and 30 min. The fading of colour followed pseudo-first-order kinetics.

Hydrophobicity, flame retardancy and antibacterial properties of cotton fabrics functionalised with MgO/methyl silicate nanocomposites

In this study, we prepared MgO nanoparticles using a hot-air spray pyrolysis method. The prepared nanoparticles were characterised using X-ray diffraction (XRD) and the crystallite size was found to be 24 nm. Scanning electron microscopy (SEM) imaging showed needle-like morphology, which was also confirmed by transmission electron microscopy. Specific surface area (24 m2 g−1) of the MgO nanoparticles was analysed using the Barrett–Emmett–Teller method. Colloidal methyl silicate and MgO nanoparticle-embedded methyl silicate solutions were prepared using the sol–gel method. Cotton fabrics were separately functionalised with silica and MgO/methyl silicate composite using an optimised pad-dry-cure method. The phase and functional group of the coated and uncoated fabrics were analysed by XRD and Fourier transform infrared spectroscopy. The surface morphology of the coated fabrics was analysed using SEM. Elemental analysis, which was carried out using energy-dispersive spectroscopy, confirmed the presence of methyl silicate and MgO nanoparticles along with cellulose on the surface of the fabric. The washing durability of the coated fabrics after 5, 10 and 15 washes was assessed using SEM, confirming the adherence of nanoparticles on the surface of the fabric. The burning performance of the coated fabrics was in the order of MgO/methyl silicate (21.4 s) > methyl silicate (17.6 s) before and after washing. The cotton fabrics coated with MgO/methyl silicate composite showed a better antibacterial activity against Staphylococcus aureus and Escherichia coli than methyl silicate-coated and uncoated fabrics. In addition, the methyl silicate- and MgO/methyl silicate composite-coated cotton fabrics showed a significant water-repellent property with water contact angles of 135.2° and 138.6° for a 5 μl water droplet.

Enhanced functional properties of cotton fabrics using TiO2/SiO2 nanocomposites

Anatase titania (TiO2) nanoparticles were prepared from natural minerals (rutile sand) using acid extraction by sol–gel method. The obtained X-ray diffraction results show that the particle possesses crystallite size of 12 nm. The colloidal silica and TiO2 nanoparticle-embedded colloidal silica solutions were prepared using sol–gel method followed by sonication process. The particle size was measured for the prepared colloidal TiO2/SiO2 sol. The prepared solution was coated on the surface of the cotton fabric through pad-dry-cure method. Elemental analysis confirms the presence of TiO2/SiO2 nanocomposite along with cellulose on the surface of the fabric. The washing durability of the coated fabrics after fifth and 10th washes indicates that the nanoparticles strongly adhered to the fabric surface. The ultraviolet resistance, burning performance, and antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria of TiO2/SiO2-coated fabric were found to be better than those of un-coated fabrics before and after washing.

Testing of the Dynamic Permeability and Deformation of Airbag Fabrics

Three different types of PA66 uncoated airbag fabrics are selected, dynamic permeability and deformation are measured by dynamic air permeability testing measurement. Average dynamic air permeability and exponent of dynamic air permeability are used to describe dynamic permeability; bulging curve and biaxial strain/stress curve are used to describe deformation. Testing results showed great useful to airbag products.

Flame-retardant coating by alternate assembly of poly(vinylphosphonic acid) and polyethylenimine for ramie fabrics

A novel intumescent flame retardant coating, consisting of poly(vinylphosphonic acid) (PVPA) as the acid source and branched polyethylenimine (BPEI) as the blowing agent, was constructed on the surface of ramie fabrics by alternate assembly to remarkably improve the flame retardancy of ramie. The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie. Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600 °C, while the control (uncoated) fabric left less than 1.4 wt% residue. Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time, and the residues well preserved the original weave structure and fiber morphology, whereas, the uncoated fabric left only ashes. Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%, relative to those of the uncoated fabric.

AFM Analysis of Fullerene C60 Coated Para-Aramid Fabric via Physical Vapor Deposition

Thin film deposition (TFD) is used to coat materials including metals, glasses and textiles with film thicknesses varying from angstrom to millimeter values. TFD methods find usage in many industries such as coating parts for engineering industries, nuclear industries and decorative industries. TFD methods are applied on textile substrates to obtain anti-static, UV-absorbing, antimicrobial, superhydrophobic and fire-resistant properties. In this study, thermal evaporation which is a TFD technique was used to coat para-aramid fabrics with Fullerene C60 nanoparticles. Samples having 0.1 μm, 0.2 μm and 0.3 μm Fullerene C60 film thicknesses were produced. Morphology and tensile properties of the samples were analysed by AFM (atomic force microscopy) analysis. An uncoated fabric was used as the control sample to compare the tensile properties of the samples. Compared to the uncoated fabric, the coated fabrics showed an increase in tensile strength. As the fullerene film thickness increased, a decrease in tensile properties was also observed. The decrease observed in the tensile properties for the C60 coated fabric samples might be caused by the coarser particles accumulating on the fabric surface as the thickness increased.

Enhanced Functional Properties of ZrO2/SiO2 Hybrid Nanosol Coated Cotton Fabrics

In this present investigation, the colloidal silica and nano ZrO2 embedded silica solution were prepared using sol-gel method followed by the sonication process. The particle size was measured for the prepared silica sol with and without ZrO2 nanoparticles. The prepared nanoparticles were coated on the cotton fabric through pad dry method. The phase and functional group analysis of the cotton fabrics after coating reveals the presence of metal oxides on the surface. The surface morphology of the coated fabrics analysed using SEM shows that the nanoparticles were in spherical morphology with slight agglomerations. The element analysis confirms the presence of silica (SiO2) and ZrO2/SiO2 nanoparticles along with cellulose on the surface. The washing durability of the coated fabrics after 5th and 10th wash indicates that the nanoparticles were strongly adhered on the fabric surface. The burning performance of coated fabrics is in the order of ZrO2/SiO2 (19.5 s) > SiO2 (11.3 s) before and after wash; UV resistance of fabric was in the order of ZrO2/SiO2 > SiO2 > uncoated fabric. Cotton fabrics coated with ZrO2/SiO2 particles show better UV and flammability protection for textile applications.

Flammability properties of PI fabric coated with montmorillonite

In this study, polyimide (PI) fabric was coated with montmorillonite (MMT) which performed as a kind of flame retardant. Thermogravimetric analysis showed that PI coated with MMT left as much as 69 % char after heating to 700 °C, about 15 % more than uncoated PI fabric. Cone calorimeter testing (heat flux: 60 kW m−2) showed that coated fabric reduced the total heat release and showed resistance to degradation from direct flame. Post-burn residues of samples were examined with SEM and revealed that the weave structure and fiber shape in all coated fabrics were preserved. In addition, heat-insulting test showed that the temperature difference of coated PI could reach 400 °C after 10 min at 800 °C. These results demonstrate that MMT coating is relatively effective for improving flame-retardant behavior to PI fabric.

Encapsulation of PCM for Thermo-Regulating Fabric Application

Polyethylene glycol (PEG) has been used as a phase change material (PCM) to create a thermo-regulating fabric. PEG-600 (Mw) was encapsulated using an in-situ polymerization technique in an oil-in water emulsion with encapsulating water-immiscible liquid by the reaction of urea with formaldehyde at acidic pH. Both FTIR analysis and DSC studies verified the formation of PEG microcapsules (MC). Melting temperature (Tm) of the microcapsules was found approximately 21°C which was the same as neat PEG. The heat storage capacity of these MCs was determined to be 12.78 J/g by DSC analysis. FTIR analysis of the MCs exhibited the peaks at 3211 cm﹣1, 1650 cm﹣1, and 1400 cm﹣1. These are the characteristic absorption peaks of -NH2, -C=O stretching and -CH bending vibrations, respectively. Fabric coated with PEG microcapsules showed a 20% higher thermal resistance, than the uncoated fabric, when heated on a Sweating Hot Plate (MTNW Corporation).

Puncture resistance of natural rubber latex unidirectional coated fabrics

A study was conducted on the puncture resistance of high-strength nonwoven natural rubber latex (NRL)-coated fabrics. High strength unidirectional (UD) polyethylene fabrics were coated using single dipping (SD), double dipping (DD), and triple dipping (TD) methods. The puncture resistance of the uncoated and coated fabrics was determined by measuring the force needed to penetrate the fabrics using a blunt probe. The mechanisms and modes of deformation involved during penetration were observed as well. In comparison with the uncoated fabrics, the SD, DD, and TD NRL coated fabrics gave higher puncture resistance of 39%, 47%, and 62%, respectively. The increments of the penetration force were proportional with the increase in the NRL-coated fabric thickness. For the uncoated fabric, the force given by the probe resulted in yarns stretching and yarn slippage upon penetration. However, the NRL-coated fabrics were not severely damaged but resulted in a curvature formed at the frontface of the fabric with minimal backface deformation. From the observations, the modes of failure were similar among the NRL-coated fabrics, that is, fiber stretching, delamination of NRL layer, and stretch marks on the fabric surface. The NRL layer acted as a protective sheath and increases the energy absorption and elasticity characteristics of the UD fabric.

Flame Retardant Behavior of Polyelectrolyte−Clay Thin Film Assemblies on Cotton Fabric

Cotton fabric was treated with flame-retardant coatings composed of branched polyethylenimine (BPEI) and sodium montmorillonite (MMT) clay, prepared via layer-by-layer (LbL) assembly. Four coating recipes were created by exposing fabric to aqueous solutions of BPEI (pH 7 or 10) and MMT (0.2 or 1 wt %). BPEI pH 10 produces the thickest films, while 1 wt % MMT gives the highest clay loading. Each coating recipe was evaluated at 5 and 20 bilayers. Thermogravimetric analysis showed that coated fabrics left as much as 13% char after heating to 500 degrees C, nearly 2 orders of magnitude more than uncoated fabric, with less than 4 wt % coming from the coating itself. These coatings also reduced afterglow time in vertical flame tests. Postburn residues of coated fabrics were examined with SEM and revealed that the weave structure and fiber shape in all coated fabrics were preserved. The BPEI pH 7/1 wt % MMT recipe was most effective. Microcombustion calorimeter testing showed that all coated fabrics reduced the total heat release and heat release capacity of the fabric. Fiber count and strength of uncoated and coated fabric are similar. These results demonstrate that LbL assembly is a relatively simple method for imparting flame-retardant behavior to cotton fabric. This work lays the foundation for using these types of thin film assemblies to make a variety of complex substrates (foam, fabrics, etc.) flame resistant.

Optical, Field-Emission, and Antimicrobial Properties of ZnO Nanostructured Films Deposited at Room Temperature by Activated Reactive Evaporation

ZnO nanostructures were deposited on flexible polymer sheet and cotton fabrics at room temperature by activated reactive evaporation. Room-temperature photoluminescence spectrum of ZnO nanostructured film exhibited a week intrinsic UV emission and a strong broad yellow-orange visible emission. TEM and HRTEM studies show that the grown nanostructures are crystalline in nature and their growth direction was identified to be along [002]. ZnO nanostructures grown on the copper-coated flexible polymer sheets exhibited stable field-emission characteristics with a threshold voltage of 2.74 V/mum (250 muA) and a very large field enhancement factor (beta) of 23,213. Cotton fabric coated with ZnO nanostructures show an excellent antimicrobial activity against Staphylococcus aureus bacteria (Gram positive), and approximately 73% reduction in the bacterial population is achieved compared to uncoated fabrics after 4 h in viability. Using a shadow mask technique, we also selectively deposited the nanostructures at room temperature on polymer substrates.

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Thin composite films of branched polyethylenimine (BPEI) and Laponite clay platelets were prepared using layer-by-layer assembly. The film thickness was tailored by altering the pH of the aqueous mixtures used to deposit these films, resulting in growth that ranged from 0.5 to 5 nm/bilayer (BL). High-pH BPEI and low-pH clay produced the thickest films. The microstructure of tilted Laponite clay platelet stacks is observed with transmission electron microscopy when using unadjusted BPEI (pH 10.3) and pH 6 Laponite. This recipe resulted in a film with 83 wt % clay and a hardness of 0.5 GPa. In all films, the clay platelets are uniformly deposited and look analogous to a cobblestone path in atomic force microscopy surface images. Several 40-BL films, with thicknesses of 100 nm or more, exhibit reduced moduli ranging from 7 to 10 GPa and hardness of around 0.5 GPa, suggesting that these transparent films could be useful as hard coatings for plastic films. These thin coatings were also deposited onto cotton fabric. Each individual cotton fiber was uniformly coated, and the fabric has significantly more char left after burning than the uncoated fabric. Thermogravimetric analysis results reveal that fabric coated with 10 BLs of BPEI/Laponite produces up to 6 wt % char at 500 degrees C, which is almost 1 order of magnitude greater than that of untreated fabric. This initial study demonstrates that polymer/clay assemblies could improve the thermal stability of cotton and may be useful for fire safety applications.

Novel UV-protective formulations for cotton, PET fabrics and their blend utilizing irradiation technique

A novel coating formulation to impart ultraviolet (UV) protection property to cotton, Polyethylene trephethalate (PET) and cotton/PET fabrics was prepared and gamma rays as an ionizing radiation was utilized for surface curing. Natural occurring aluminum potassium sulfate (Alum) was used individually and in binary coat with Zinc Oxide (ZnO), to induce the UV-blocking properties. It was found that using Alum (0.3 g/ml) caused a prompt increase in ultraviolet protection factor (UPF) over the uncoated fabrics. Moreover, the incorporated ZnO in the binary coat increased the UPF for two to threefold than the stand-alone Alum coating, specially in case of PET coated fabric. Water absorbance and moisture regain of ZnO and Alum/ZnO coated fabrics showed a decrease over the blank samples, due to the usage of oligomer/monomer combination. On contrary, Alum showed a hydrophilic effect with the increase in its content in the formulation. Surface Electron Microscope showed the homogenous coating of fibers. X-ray diffraction (XRD), energy dispersive X-ray (EDX) and water vapor permeability were also tested for coated samples.

Antifungal Textiles Formed Using Silver Deposition in Supercritical Carbon Dioxide

The antifungal properties of two silver-coated natural cotton fiber structures prepared using a supercritical carbon dioxide (scCO2) solvent were examined. Scanning electron microscopy confirmed that the scCO2 process may be used to produce cotton fiber textiles with uniform silver nanoparticle coatings. A version of the Kirby-Bauer disk diffusion test was used to assess the ability of these textiles to inhibit fungal growth. Cotton fabric samples modified with Ag(hepta) and Ag(cod)(hfac) exhibited measurable zones of inhibition. On the other hand, the uncoated fabric had no zone of inhibition. Possible applications of antifungal textiles prepared using scCO2 processing include use in hospital uniforms and wound dressings.

Influence of Nano Silica Coating on the Functional Properties of Cotton Fabrics

Coating of nanoparticles on fabrics provides huge potential applications in textile industry. The microencapsulation process is used to encapsulate the nanosilica particles which is used to coat on the surface of fabrics and to observe the special properties such as anti-bacterial, wrinkle resistance, etc. The amorphous nano silica particles were prepared from the natural resources through chemical route. The encapsulated nano silica was prepared using sodium alginate as a wall material by the coacervation method. The prepared sample was coated on the surface of the fabrics by pad-dry-cure method. The anti-bacterial studies were carried out for the nano silica coated and uncoated fabrics and the results would demonstrate the antibacterial effectiveness of treated cotton fabrics. The basic properties like tensile strength, tear strength, air permeability, crease recovery and whiteness index have been analysed for the coated and uncoated fabrics.

Surface dyeability of cotton and nylon fabrics coated with a novel porous silk fibroin/silica nanohybrid

AbstractA new and facile approach of surface dyeing was developed for cotton and nylon fabrics coated with a novel porous silk fibroin (SF)/silica (SiO2) nanohybrid. Actually, dyeing of the fabrics occurred in the very thin nanohybrid layers exclusively, while the main body of the fabrics remained intact on the whole. With the assistance of the large surface areas of the porous nanohybrid, dye uptake of the coated cotton fabrics dyed with Acid Red GSF or Disperse Cation Red SD‐GRL was enhanced substantially compared with that of the uncoated fabrics as a control. Moreover, dye uptake increased with the SF content in the hybrid, indicating that the SF moiety played a significant role for the surface dyeing process. Color fastness to water of both the dyestuffs was much higher for the coated cotton fabrics compared with that of the uncoated ones. Similar results were obtained for the nanohybrid coated nylon fabrics dyed with Disperse Cation Red SD‐GRL as those of the coated cotton fabrics. However, no increase was observed for dye uptake of the coated nylon fabrics dyed with Acid Red GSF owing to saturation of the dyestuff attached on the controlled uncoated nylon fabrics, which concealed the contribution of the nanohybrid layer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Water vapor permeability of cotton fabrics coated with shape memory polyurethane

In this paper, we have investigated the water vapor permeability of shape memory polyurethane (SMPU) coated cotton fabrics. The SMPUs were tailor made in order to obtain the phase transition temperature (soft segment crystal melting temperature) in the room temperature range. SEM studies were carried out in order to investigate the surface structure of coated and uncoated fabrics. The temperature sensitive water vapor permeability at soft segment crystal melting point was observed for SMPU coated fabrics. When the experimental temperature reached the soft segment crystal temperature of SMPU, an abrupt change of water vapor permeability of SMPU coated fabrics were observed. The significant change of water vapor permeability of SMPU coated fabrics is due to the phase change of SMPU which causes density changes inside the membranes due to micro-Brownian motion of soft segment, therefore, enhanced the water vapor permeability through the coated fabrics. The water vapor permeability of coated fabrics was also dependent on the primary structure of SMPU. When polycaprolactone glycol (PCL, M n 3000 g mol −1) was introduced in the polytetramethylene glycol (PTMG, M n 2900 g mol −1) based SMPU, the water vapor permeability decreases due to the increased interaction between the polymer chains due to presence of ester groups. In contrast increase of polyethylene glycol ( M n 3400 g mol −1) in the SMPU backbone, the WVP increases due to the increasing hydrophilicity of the SMPU.