Conductive cotton fabrics for heat generation prepared by mist polymerization

Cotton fabrics were coated with conducting polypyrrole (PPy) by mist polymerization derived from aqueous solution of pyrrole (Py) with ferric chloride (FeCl₃) as oxidant. The polymerization conditions, such as the reaction time and the concentrations of monomer and oxidant, were systematically investigated. The prepared PPy-coated fabrics could keep their temperature at about 24–44 °C when charged by a fixed DC voltage of 1–3 V. The results indicate that these PPy-coated fabrics can be used potentially as heating pads and integrated into the apparel to make the wearer warm enough using a portable battery. Furthermore, such fabrics are more comfortable than the conventional heating pads due to their flexibility and breathability.     

Optimization of polymerization conditions and thermal degradation of conducting polypyrrole coated polyester fabrics

PET fabric is coated with conducting polypyrrole (PPy) by oxidative polymerization from an aqueous solution of Py using ferric chloride hexahydrate (FeCl₃) as oxidant and p-toluene sulphonate (pTSA) as dopant. The optimum concentrations for Py, FeCl₃ and pTSA were found to be 0.11, 0.857 and 0.077 mol/l respectively, which yielded a conductive fabrics with resistivity as low as 72 Ω/sq. PPy fabric gained resistivity less than one order of magnitude when aged for 18 months at room temperature. The stabilizing effect of the dopant pTSA against thermal degradation was demonstrated; the undoped samples reached resistivity of around 40 kΩ, whereas doped samples reached less than 2 kΩ at the same temperature and time.     

Modeling spun yarns migratory properties using artificial neural network

The mechanical and physical properties of spun yarns and fabrics depend not only on properties of constituent fibers, but also the yarn structure characterized by geometrical arrangement of fibers in the yarn body. Although there are many studies related to analyzing the migratory properties of spun yarns, there are no studies available about predicting yarn migration parameters. Therefore, the main aim of this research is to introduce a new approach to predict migratory properties of different kinds of spun yarns, namely siro, solo, compact and conventional ring-spun yarns. To achieve the objectives of the research, general physical and mechanical properties of spun yarns together with existing standards were thoroughly studied. Spun yarn migratory properties were predicted using intelligent technique of artificial neural network (ANN). Results signified that the ANN models can predict precisely the yarn migratory properties on the basis of a series of yarn physical and mechanical properties.     

Surface modifications of natural Kanchipuram silk (pattu) fibers using glow discharge air Plasma

Experimental investigations have been carried out to modify the surface properties of natural Kanchipuram silk (pattu) fibers using a low temperature DC glow discharge air Plasma. Silk is an externally spun fibrous protein secretion formed into fibers. Plasma treatment is an eco-friendly, dry, and clean process over wet chemical method and does not suffer from any environmental and health concerns. Experiments have been performed considering three parameters such as discharge current, treatment time, and working pressure. The structural, thermal, morphological, optical, and mechanical studies of raw and plasma treated silk fibers have been obtained out using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), thermo gravimetric analyzer (TGA), scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), diffuse absorbance spectroscopy, and tensile test. A comparative study has been done for the untreated and different treated fibers. Various characterization analyses reveal that surface roughness of the plasma treated silk fiber is increased and also crystallite size of treated samples is enhanced, plasma treated silk fibers maintain the whiteness effect and it is observed that UV transmittance region (A & B) is more for the treated fiber which signifies enhanced UV protection.     

Mechanism and Analysis of Laccase-mediated Coloration of Silk Fabrics

Laccase provides a mild and eco-friendly alternative for the dyeing of fabrics. In this study, laccase-mediated catalytic oxidation was employed in coloration of silk fabrics, and the color was then assessed. The surfaces of silk fabrics were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Their thermal and crystallization properties were also investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), and Xray diffraction (XRD). The textile softness was evaluated by the bending rigidity (B). In addition, high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-VIS) spectroscopy were employed to analyze hydrolysate of silk fabrics obtained from hydrolysis with hydrochloric acid solution. The results demonstrated that a stable reddish-yellow layer was formed on the surface of silk fabrics by the laccase-mediated coupling of phenol hydroxyl side chains in the silk polypeptide. Moreover, the SEM and AFM observations showed that the surface of colored silk fiber was slick. ATR-FTIR and XPS results demonstrated differences in the C, N, O contents and the functional groups of the uncolored and colored silk fabrics. The DSC, TG, and XRD indicated that the thermal properties of silk fabrics were not affected by laccase and the coupling reaction mainly occurred in the amorphous region. The DMF extraction test further illustrated that covalent bonds were formed between tyrosine residues constituent of silk peptides. Finally, HPLC and UV-VIS results showed that new substances were formed as a result of conjugation between benzene rings.     

Developing an intelligent fiber migration simulator in spun yarns using a genetic fuzzy system

The mechanical and physical properties of spun yarns and fabrics depend not only on mechanical properties of the fibers making up the yarn, but also geometrical arrangement of fibers, known as fiber migration. The main aim of this research is to introduce a new approach to predict migratory behavior of spun yarns. Achieving the objectives of this research, general physical, mechanical and structural properties of spun yarns together with existing standards were thoroughly studied. A hybrid intelligent model was developed based on a Genetic Fuzzy System (GFS) to model the relationships between migration of fibers in spun yarns and some physical and mechanical properties of spun yarns. Results indicated that the developed fuzzy expert system can be used as an intelligent simulator to predict yarn migratory parameters.     

Reducing silk fibrillation through MMA graft method

Silk fibrillation, one major weakness of silk fibers, can lead to undesirable fabric appearance. In this research, an effective method for reducing the fibrillation of silk fibers through the graft copolymerization with methyl methacrylate (MMA) has been developed. The major copolymerization factors such as the initiator concentration, MMA monomer concentration, reaction time and temperature were investigated. An AATCC Crockmeter was used to rub the fabric to simulate the abrasion in production to generate the fibrillation. The microscope observation and the evaluation of fibrillation index (FI) were applied to assess the degree of fibrillation of silk fibers. The optimum graft copolymerization factors were obtained. Instrumental analyses, such as FTIR, TG and SEM, proved that the silk fabric had been successfully grafted with MMA monomers. The fibrillation of the grafted silk fibers was considerably reduced since the coated PMMA can protect the silk fiber. In addition, the physical properties such as the crease recovery, breaking strength, and the breaking length of the grafted silk fabrics were also improved.     

Key Characteristics of a Novel Silk Yarn from Fresh Cocoons

We studied the key characteristics of a novel silk yarn reeled from fresh cocoons. Compared with traditional silk yarn, this novel silk yarn displayed better mechanical properties, especially in terms of a higher breaking stress and toughness, and exhibited a different surface morphology. A cross-sectional observation and the sericin content results illustrated that different sericin coatings on the silk yarn reeled from fresh cocoons surface did not improve the mechanical properties. The degumming and tensile testing analysis indicated that degummed silk fibroin of novel silk yarn is able to resist deformation and fracture better than silk fibroin of traditional silk yarn. The FTIR results revealed that the selected techniques is an important contributor to the silk fibroin mechanical properties, because novel technique brought higher percentage beta-sheet structures in novel silk yarn fibroin than traditional silk yarn. The new technique that using novel silk yarn has improved its mechanical properties and it is expected that the silk yarn with superior mechanical properties could be used in fabrics transistors, electrodes and reinforced biomaterials.     

Preparation and characterization of electro-conductive rotor yarn by in situ chemical polymerization of pyrrole

This work describes a novel method for preparing electro-conductive rotor yarns by in situ oxidative chemical polymerization of pyrrole. The effects of different process parameters on electrical resistivity of the yarn were studied by using Box-Behnken response surface design. The concentration of monomer, polymerization time and polymerization temperature were found to influence the electrical resistivity of the yarn. It was observed that electrical resistivity of the yarn increased linearly with increase of measuring length of it. Whereas the effects of yarn twist and tensile strain found to had negative correlation with electrical resistivity of electro-conductive rotor yarns. Microscopic image analysis showed that there was uniform distribution of PPy polymer on the surface of cotton fibres and FTIR analysis depicted possible chemical interaction between polypyrrole and cellulose.     

Depositon of ZnO on polyacrylonitrile fiber by thermal solvent coating

In this study, the surface functionalization of polyacrylonitrile (PAN) fibers was achieved by depositing ZnO nanoparticles using thermal solvent coating. surface morphology, crystalline structure, surface chemistry, thermal stability and washing stability of the ZnO coated PAN fibers were investigated by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform Infra red spectroscopy (FT-IR), Thermo-gravimetric analyses (TGA) and washing stability test, respectively. In addition, the weight changes after coating and washing were studied at different coating and washing conditions. The SEM images revealed that the ZnO was well coated on the surface of the PAN fibers and the coating was obviously affected by the experimental temperature. The FT-IR spectra indicated the chemical features of the deposited ZnO nanostructures. The XRD patterns showed that there was a typical crystalline structure of ZnO nanogains formed on the PAN fibers after coating. The TGA results revealed that the thermal stability of the PAN fibers was improved by the ZnO coating. The experimental results of washing stability revealed the effect of temperature on the washing stability. Weight measurements indicated that the amount of ZnO deposited on PAN fibers increased with the increasing of coating temperature from 60 to 70 °C. Weight measurements also revealed that the weight of the ZnO coating on fibers decreased with the increase in washing temperature and washing time.     

Handle,fit and pressure comfort of silk/hybrid yarn woven stretch fabrics

Hybrid yarn was produced by twisting silk with nylon covered lycra yarn. Silk of 20 D in warp and hybrid yarn in weft was woven to develop lustrous woven stretch fabrics for sari blouse. Silk and hybrid yarn fabrics were produced in three different weaves namely plain, crepe and sateen. An in-depth study was carried out to understand the effect of weave on thermal comfort; low stress mechanical properties, total hand value and stretch properties. Nine blouses (3 samples× 3 figures) were constructed from three different woven stretch materials for fit assessment and objective pressure comfort test. The effect of fabric weave, low stress mechanical properties, total hand value and stretch properties on fit and pressure comfort of silk/hybrid yarn stretch fabrics were analyzed. Sateen weave silk/hybrid yarn stretch fabric shows higher total hand value, stretch properties and better thermal comfort properties. Sateen and crepe weave stretch fabrics provided good fit. Sateen weave fabric exerted lower clothing pressure value in the range of 3-12 mmHg at all body locations in standing position and in different postures.     

Synthesis and characterization of electrically conductive composite films of polypyrrole/poly(acrylonitrile-co-styrene)

Homogeneus Polypyrrole (PPy)/poly(acrylonitrile-co-styrene) (SAN) composite thin films were prepared by chemical polymerization of pyrrole on poly(acrylonitrile-co-styrene) matrix. Ce (IV) is used as an oxidant for in-situ polymerizion of pyrrole on SAN matrix, having an advantageous over the impregnation method. The formation and incorporation of PPy in the copolymer matrix were confirmed by FTIR-ATR and UV-Visible spectrophotometric measurements. Thermal analyses showed that after polymerization of Py in copolymer matrix, thermal behavior of SAN was changed and derivative of weight loss at this temperature was increased by increasing of PPy content. XPS and FTIR-ATR analysis of composite films indicated cerium salt with nitrate ion acted as a dopant. The increase in the AC electrical conductivity of the PPy/SAN composites over pure SAN was observed. At lower frequency up to 10⁵ Hz, conductivity was shown an independent behavior from frequency; but at high frequencies (10⁵–10⁷ Hz), dependence on frequency was explained by polaron and bipolaron formations of PPy. The dispersion of PPy particles in copolymer matrix was proven by SEM, AFM and digital camera. By the increase of PPy content in the composite films, increase in AC conductivities, and decrease in dielectric constants and loss were observed.     

A novel method to reduce hairiness level of ring spun yarn

The quality of ring spun yarns is largely determined by its level of hairiness. The existence of hairiness inevitably affects the quality of ring spun yarns. This paper presents an innovative method on lowering the level of hairiness of ring spun yarns. This can be achieved by shooting compressed air to the yarn, through a swirl nozzle comprising a yarn duct and an airjet nozzle attached to a traditional ring spin frame. When compressed air is applied from the air-jet nozzle to the yarn duct, the swirling air flow tucks surface fibers of the ring spun yarns into its body. Four controllable variable parameters for the process, supplied pressure, nozzle position, twist factor and spindle speed, and their effects on the lowering of yarn hairiness will be clarified. Their impact on the quality of the yarn is statistically analyzed, and the optimum outcome of the combination of parameters for the process, will thus be determined.     

Improvement of thermoregulating performance for outlast/silk fabric by the incorporation of polyurethane microcapsule containing paraffin

The purpose of this work is to improve the thermoregulating performance of Outlast/silk fabric by means of the incorporation of polyurethane microcapsules containing paraffin. The effect of degumming and dyeing process on the heat storage capacity of Outlast/silk fabric was investigated. The endothermic enthalpy of Outlast/silk fabric was found to decrease from 5.41 J/g to 3.94 J/g after that processes. Polyurethane (PU) microcapsules were prepared with paraffin to serve as the core and polyurethane as the shell. The microstructure, morphology as well as phase-change property were systematically characterized by Fourier Transform Infrared spectra (FTIR), Optical Microscope (OM), Scanning Electron Microscope (SEM) and Differential Scanning Calorimetry (DSC). Subsequently, the prepared PU microcapsules were coated onto the Outlast/silk fabric by a conventional coating technique. The results showed that the endothermic enthalpy of the resultant fabric increased to 7.71 J/g, and the prepared PU microcapsules were firmly adhered on the surface of Outlast/silk fabric.     

Preparation and characterizations of polypyrrole on liquid ammonia pre-treated wool fabric

Wool fabric was treated with liquid ammonia at -40 °C for 30 and 60 s prior to the application of polypyrrole (PPy). The polymer was deposited on wool fiber using the chemical oxidation method with 0.02 and 0.05 mol/l (Py) monomer concentration and FeCl₃ as a catalyst. Functional groups of wool samples were analyzed using FT-IR, and surface morphology was investigated using SEM micrographs. Properties such as water absorbency, surface resistivity, abrasion resistance, weight add-on, and air permeability of coated specimens were explored. The FT-IR outcomes revealed the liquid ammonia pre-treatment changed the amount of amide I (NH), cystic acid, cystic monoxide, and dioxide content of the fiber. SEM micrographs revealed the descaling of wool surface after pre-treatment and smooth coating of polymer. Pre-treatment of wool in liquid ammonia improved absorbency of wool fabric with respect to the treatment duration. The surface resistivity of wool fabric decreased with the increase of monomer concentration and pre-treatment duration. The results of abrasion resistance confirmed that the pre-treated fabric exhibited lower loss of polymer after 200 cycles of abrasion. The weight of the fabric was increased and air permeability decreased when the monomer concentration and liquid ammonia pre-treatment duration was increased.     

Characterization of castor oil/polycaprolactone polyurethane biocomposites reinforced with hemp fibers

Abstact  The thermal and mechanical properties of castor oil/polycaprolactone-based polyurethane (CPU) films and polyurethane biocomposites reinforced with hemp fibers (HCPU) were investigated. Although similar films can be synthesized from petroleum, the main interest in studying these biomass-based composites is based on the fact that both fiber and matrix are derived from renewable resources. In this study, castor oil was used as a polyol for polyurethane films and hemp fiber was used to reinforce the biocomposites. To control the mechanical properties of CPU and HCPU, polycaprolactone diol (PCL) was added to the polyol mixture. Varying the mixing ratio of castor oil and PCL, the thermal and mechanical properties of the CPU and HCPU samples were investigated by using FT-IR, DSC, DMTA, Minimat, and SEM. In an attempt to improve interfacial adhesion between the fiber and matrix biocomposites, hemp fiber was reacted with MDI. FE-SEM micrographs showed that the surface of the hemp fiber became smoother after reaction with MDI. Urethane bonding formation was confirmed by FT-IR.     

Comparative study of cellulase treatment on low stress mechanical properties of cotton denim fabric made by torque-free ring spun yarn

Cellulase is useful for bio-polishing cotton fabrics which enhances their aesthetic performance instead of stonewashing process. Torque-free ring spun process is a widely used technique to produce newly low-twist and balanced torque yarns with soft hand. In this paper, denim fabrics woven with torque-free ring spun yarn and conventional ring spun yarn respectively were treated with cellulase under the same condition and their fabric handle, expressed as low stress mechanical properties, such as tensile strength, bending, shearing, compression and surface performance were investigated by Kawabata Evaluation System for Fabric (KES-F). After cellulase treatment, both denim fabrics revealed better flexibility, elasticity recovery, raised shearing stiffness, fluffier and improved smoothness. While torque-free ring spun yarn made denim fabric showed a better fabric handle than conventional ring spun yarn made denim fabric.     

Structural analysis of finer cotton yarns produced by conventional and modified ring spinning system

Yarn structure plays an important role in determining the properties of spun yarns. Recently, a modified spinning technique has been developed for producing a low torque and soft handle singles yarn by modifying the fiber arrangement in a yarn. Comparative studies revealed that the finer modified yarns possess significantly higher strength and lower hairiness over the conventional yarns of the same twist level, implying a different structure of finer modified yarn. Thus this paper aims to quantitatively study the structures of the finer conventional and modified cotton yarn (80 Ne) produced at the same twist level. Various measuring techniques, namely the Scanning Electron Microscope (SEM), cross section technique and tracer fiber technique, are adopted to analyze their structural characteristics, including fiber configuration, fiber spatial orientation angle, fiber packing density, yarn surface appearance, and fiber migration behavior. Results showed that finer modified yarns exhibit a smoother surface and much more compact structure with less hairiness. The fibers in the finer modified yarn have a complicated fiber path with relatively lower fiber radial position, larger migration frequency and magnitudes. In addition, it was noted that 73% of fibers in the finer conventional yarn follow concentric conical helix, which is contrary to those in the coarser conventional yarn. The analyses conducted in this paper provide deep insights into the mechanism of modified spinning technique and evidential explanations on the difference of properties between the finer conventional and modified yarns.     

Bending behavior of coated yarns

Cotton yarns were coated with a polymer solution to hold surface fibers to the yarn body, which caused fiber-fly generation during knitting process. The physical property of the coated yarn, especially a bending rigidity was investigated in order to evaluate the performance of the coated yarn during knitting. SEM images showing the surface condition of the coated yarn demonstrated that the thickness of a coating material increased as the concentration of the coating solution increased. The results of the bending rigidity measured using KES-FB2 system showed that the bending rigidity of the coated yarn increased as the concentration of the coating solution increased. The results also revealed the possibility that yarn coated with a low amount of coating material should be employed for further research of reducing fiber-fly generation during knitting process.     

Structure and performance of fibers prepared from liquefied wood in phenol

The fibers from liquefied wood in phenol (WPFs) were spun by adding hexamethylenetetramine as synthetics and cured by soaking in solution containing hydrochloric acid and formaldehyde as main components. The chemical structure of WPFs remarkably changed from that of liquefied wood was identified by FT-IR spectrometer. WPFs with the average diameter of 27∼42 μm, tensile strength of 230∼356 MPa, and modulus of 15∼31 GPa were obtained using spinning speed of 0.72 μm min⁻¹, hydrochloric acid concentration of 18.5 %, heating rate of 10 °C h⁻¹, and curing time of 4 h. These WPFs showed a high thermal stability and a complex thermal decomposition process by TG(thermogravimetric) analysis. It was also found that the two obvious weight loss temperatures of WPFs were 510°C and 748°C.