Studies on electro-conductive fabrics prepared by in situ chemical polymerization of mixtures of pyrrole and thiophene onto polyester

This article reports on development, characterization, and performance of electro-conductive textiles prepared by in-situ chemical polymerization of mixtures of pyrrole and thiophene onto a polyester fabric. It was observed that a mixture of pyrrole and thiophene at 4:1 molar ratio resulted in the lowest surface resistivity among all the mixtures and the individual monomers studied. This electro-conductive fabric exhibited exponential voltage-current relationship. Further, it showed substantial fall in surface resistivity under the exposure of ultra-violet radiation. Under the application of DC voltage across it, an exponential rise in surface temperature was observed and the coefficient of rise in temperature was found to be directly related to the duration of voltage applied. Further, when subjected to mechanical straining, it displayed a decrease in resistivity followed by an increase of resistivity.     

Preparation and characterization of high molecular weight poly(trimethylene terephthalate) by solid-state polymerization

Solid-state polymerization of poly(trimethylene terephthalate)(PTT) was carried out to obtain high molecular weight polymers. Two kinds of commercial PTT chips were polymerized in the solid state by the heat treatment at 190∼220°C for various times and they were characterized by end group content, molecular weight, thermal analysis, and X-ray diffraction. In the solid-state polymerization of PTT, the overall reaction rate was governed by the solid-state polymerization temperature and time, and pellet size. The content of carboxyl end groups decreased during the solid-state polymerization with increasing solid-state polymerization temperature and time. The melting temperature and crystallinity of the PTT were higher for the ones treated at higher temperature and longer time. The activation energy for the solid-state polymerization of PTT was in the range of 24∼25 kcal/mol for both chips. Through the solid-state polymerization of commercial PTT chips, high molecular weight polymers up to an intrinsic viscosity of 1.63 dl/g was obtained, which corresponded to about a 117,000 weight-average molecular weight.     

Prediction of rotor spun yarn strength using support vector machines method

A new method for rotor spun yarn prediction from fiber properties based on the theory of support vector machines (SVM) was introduced. The SVM represents a new approach to supervised pattern classification and has been successfully applied to a wide range of pattern recognition problems. In this study, high volume instrument (HVI) and advanced fiber information system (Uster AFIS) fiber test results consisting of different fiber properties are used to predict the rotor spun yarn strength. The results obtained through this study indicated that the SVM method would become a powerful tool for predicting rotor spun yarn strength. The relative importance of each fiber property on the rotor spun yarn strength is also expected. The study shows also that the combination of SVM parameters and optimal search method chosen in the model development played an important role in better performance of the model. The predictive performances are estimated and compared to those provided by ANFIS model.     

Effect of two separate fibre feed systems in rotor spinning on yarn properties

Opening of the fibres in all industrial rotor spinning units is being done by an opening roller, which intakes the fibres from one feed point. Increasing number of feed rollers from one to two may improve fibre opening on the opening roller by gradual loading of the opening roller, which may improve fibre orientation in the final yarn and yarn properties. In this research a modified SE-8 rotor spinning unit of Suessen was used in which two separate fibre feed systems were employed. Raw material used was 38 mm, 1.7 den viscose fibre, to spin a 40 tex yarn. Yarn properties produced with this unit, were compared with that of the original yarn. Yarn properties tested were tenacity, extension, work of rupture, mass irregularity and imperfections, abrasion resistance and hairiness, which were measured on Shirley (SDL) and keisokki yarn testing machines. Test results were analyzed by ANOVA for any difference between the means, and Tukey and Duncan for classification and ranking of the yarn properties. Test results showed that, tenacity, extension and work of rupture of the modified yarn increased in comparison to the original yarn. Its mass irregularity, number of thin places and neps, and hairiness decreased. Number of thick places and yarn abrasion didn’t change. According to the test results, it was concluded that increasing the number of feed rollers on the opening roller from one to two has improved yarn properties.     

Fabrication and characterization of PET nanofiber hollow yarn

In this study, various concentrations of polyethylene terephthalate (PET) polymeric solution were investigated to produce hollow nanofiber yarn. First, the electrospining apparatus was designed in a way that to put PVA multifilament in the core and to twist PET nanofibers onto multifilament yarn as a sheath simultaneously, followed by dissolving PVA yarn in hot water, PET hollow nanofiber yarn was produced. In this survey, it has been observed that the average thickness of sheath increased by increasing concentrations of PET polymeric solution. Results showed that maximum efficiency of extracting the PVA multifilament from the hollow yarn under certain conditions (concentration of 18 % (w/v) of PET, applied voltage of 10 kV, and flow rate of 0.0526 ml/h) was more than 85 %. The mechanical and physical properties of PET hollow yarns were investigated and indicated that the hollow nanofiber yarns at concentration of 30 % and 18 % polymeric solution had the lowest strength and the highest regain moisture, respectively.     

Multiple response optimization of rotor yarn for strength,unevenness, hairiness and imperfections

In this study, a multiple response optimization model based on response surface methodology was developed to determine the best rotor speed and yarn twist level for optimum rotor yarn strength and unevenness, and minimum yarn hairiness and imperfections. Cotton yarn of 30 tex, was produced on rotor spinning machine with different twist levels (i.e. 500, 550, 600 and 700 tpm) at different rotor speeds (i.e. 70000, 80000, 90000 and 100000 rpm). Yarn quality characteristics were determined for all the experiments. Based on the results, multiple response optimization model was developed using response surface regression on MINITAB® 16 statistical tool. Optimization results indicate that with the quality of raw material selected for this study, top 50 % quality level, according to USTER® yarn quality benchmarks, can be achieved with 100 % desirability satisfaction for all the selected yarn quality parameters at rotor speed of 77,800 rpm and yarn twist of 700 twists per meter.     

Analysis and in-plane shear characterization of polyester plain fabric by yarn pull-out method

The aim of this study was to determine the in-plane shear properties of polyester fabric by the pull-out method and analytical relations were developed to calculate the shearing properties. After the yarn in the fabric was pulled from the top ravel region before the start of the crimp extension stage, it was found that fabric shear strength and rigidity increased when the number of pulled ends increased. In addition, when the fabric width and length increased, fabric shear strength and rigidity increased. On the other hand, the shear strength and rigidity values in untreated fabric were high compared to that of treated fabric due to the fabric treatments by softening agent. It was observed that fabric sample dimensions and the number of pull-out ends as well as the fabric treatments influenced fabric shear strength and rigidity. Also, the shear jamming angles were found to be based on the number of pulled ends. Fabric local shearing properties could be identified by pulling the yarn ends in various regions of the fabric. This could be important for the handling of the fabric during formation. The results generated from this study showed that polyester fabric shear could be measured by the yarn pull-out test.     

Comparison of the new methodologies for predicting the CSP strength of rotor yarn

This paper provides preliminary results on the relative performance of the adaptive neuro-fuzzy system inference (ANFIS) model versus linear multiple regression method, when applied to the use of cotton fiber properties to predict spun yarn strength obtained from open-end rotor spinning. Fiber properties and yarn count are used as inputs to train the two models and the output (dependent variable) would be the count-strength-product (CSP) of the yarn. The predictive performances of the two models are estimated and compared. We found that the ANFIS has a better average prediction successful in comparison with linear multiple regression model.     

Preparation of selective ion adsorbent by photo curing with acrylic and phosphoric acid on jute yarn

Jute yarns were cured with acrylic acid (AA) and phosphoric acid (PA) using UV radiation in order to prepare selective ion adsorbent. A series of formulations were prepared in methanol containing varying percentages of (10–70 %) of AA and 2 % photo-initiator (PI) (Darocur-4043). jute yarns were soaked in this formulation for various soaking times (10–30 min) and cured under UV radiation of different intensities (20–50 UV passes). Concentration of AA, soaking time and intensity of UV radiation were optimized based on polymer loading (PL). The maximum PL (21 %) was observed for 50 % AA solution for 20 min soaking time at 40 UV passes. Various formulations were prepared using 5–15 % (w/w) of phosphoric acid, 50 % AA and 2 % PI in methanol. Then jute yarns were soaked in this solution for 20 min and irradiated at 40th UV pass. The concentration of PA was again optimized for maximum PL. It was found that the formulation containing 10 % PA, 50 % AA, 38 % methanol and 2 % PI showed 70.95 % of PL. To investigate the adsorbent behavior, a 10 ppm CuSO₄ solution was prepared and then grafted yarns were soaked in the solutions for 30–300 min at different conditions. After withdrawing the yarns, the remaining copper in the solution were measured by atomic absorption spectrophotometer (AAS). It was revealed that copper was successfully removed by using the grafted jute yarns.     

Prediction of rotor spun yarn strength from cotton fiber properties using adaptive neuro-fuzzy inference system method

In this study, we present the application of a hybrid neuro-fuzzy system for the prediction of cotton rotor spun yarn strength from cotton fiber properties. The proposed system possesses the advantages of both artificial neural networks and fuzzy logic, and is thus more intelligent. HVI (high volume instrument) and Uster AFIS (advanced fiber information system) fiber test results are used to train the neuro-fuzzy inference system. We also study the degree of impact of each fiber property on the rotor spun yarn strength. Fiber strength, upper half mean length, length uniformity and yarn count have a positive impact whereas micronaire, yellowness and short fiber content have a negative impact on rotor spun yarn strength.     

Synthesis and characterization of polyacrylate sizes modified by nano-microspheres prepared via miniemulsion polymerization

This paper firstly stated the fabrication of silica particles via Sol-Gel method and their modification by Silane coupling agent ??-MPS (3-Methacryloxypropyltrimethoxysilane). Pure PSt (Polystyrene) and silica/PSt microspheres were prepared via miniemulsion polymerization. We added these two microspheres to SX-5 size respectively to form the nanomodified sizes. These nano-particles were characterized by means of FTIR (Fourier Transmission Infrared Spectroscopy), DLS (Dynamic Light Scattering) and TEM (Transmission Electron Microscope). Then the properties of sizes (SX-5, nanomodified SX-5, PVA (Polyvinyl Alcohol) 1799), size films, sized yarns, and removability of sizes were characterized. Experimental results show that silica/PSt modified SX-5 had the best properties of sizes, and the best properties presented in size films and sized yarns. This result can be suggested that small size effect, high fluidity, high surface energy and tough surface morphology of silica/PSt microspheres, playing a role as cross-linker and reinforcement, will enhance the mechanical properties of SX-5 and increase the interfacial adhesion force between sizes and yarns.     

Preparation and characterization of poly(2-hydroxyethyl methacrylate) grafted bacterial cellulose using atom transfer radical polymerization

The purpose of this study is to synthesize grafted Bacterial Cellulose (BC) nanofibers using Atom Transfer Radical Polymerization (ATRP) reinforced into poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel matrix. Nanofibers grafting polymerizations were conducted in the presence of the catalyst CuCl/CuBr and the initiator 2-bromoisobutyrylbromide (2-BiBr). Degrees of substitution (DS) of BC-macroinitiators were quantified using both elemental analysis and gravimetric method. FTIR results confirmed BC nanofibers’ surface modifications of both initiator and hydroxyethyl methacrylate (HEMA) grafts. X-ray spectroscopy further confirmed the increase in carbonyl content after PHEMA-grafting polymerization. Results of the gravimetric analysis showed an increase in the weight of the grafted BC upon increasing reaction time. Furthermore, the change in the swelling ratio percentages of the reinforced composites product (BC-MI-3-g-PHEMA-1.5) was considerably higher based on reaction time. Slight increase in the swelling ratio of BC-MI-3 nanofibers was observed after 48 hours to reach 31 %. Moreover, results of thermal gravimetric analysis (TGA) demonstrated that decomposition temperature at 50 % weight loss (T₅₀) decreased to 350 °C for BC-MI-3-g-PHEMA-1.5. These characteristics demonstrate potentials for applications in the biomedical fields including drug delivery and wound care.     

Poly(ethylene 2,6-naphthalate)/MWNT nanocomposites prepared by in situ polymerization: Rheological and mechanical properties

Poly(ethylene 2,6-naphthalate)/multi-walled carbon nanotube (PEN/MWNT) nanocomposites are prepared by in situ condensation polymerization in the presence of various acid-treated MWNT (a-MWNT) contents and their morphology, rheological and mechanical properties are investigated as a function of the a-MWNT content. SEM image of a plasma-etched nanocomposite exhibits that a-MWNTs are dispersed well in the PEN matrix by forming an interconnected network structure. Accordingly, rheological properties such as complex viscosities and shear moduli of PEN/a-MWNT nanocomposites at the terminal region of low frequency are much higher than those of pure PEN. Glass transition temperatures of nanocomposites also increase with the increment of the a-MWNT content, which stems from the reduced chain mobility due to the specific interaction between a-MWNTs and PEN matrix. Dynamic and tensile mechanical properties of nanocomposites are also higher than those of pure PEN and they increase with the increment of the a-MWNT content. The highly improved mechanical properties of PEN/a-MWNT nanocomposites are explained to originate from the interconnected network structure of a-MWNTs in PEN matrix as well as the strong interfacial adhesion between a-MWNTs and PEN matrix.     

Wicking properties of polyamide 66 twisted nanofiber yarn by tracing the color alteration in yarn structure

In view of the interest in wicking properties of these flexible structures, analysis of the wicking phenomena in nylon 6.6 nanofiber yarns is carried out by considering the twist rate effects. A novel method is used based on adding a pH-sensitive dye to yarn interstructure and the analysis of color alteration of nanofiber yarn structure, resulting from a shift in pH, during the capillary rise of distilled water. The results show that the addition of pH- sensitive dye has no influence on the average nanofiber diameter and the wicking behavior of yarns. This study shows that in short durations, the kinetic of the capillary rise follows the Lucas-Washburn equation. The Lambertw, a mathematical function, has been incorporated, which helps measure an equivalent structural factor of nanofiber yarns and vertical wicking height at any given time considering the gravitational effects. The statistical results show that the average of equilibrium wicking height and capillary rise rate coefficient tend to decrease with increasing the nanofiber yarn twist, due to the reduction of continuity and size of capillaries.     

Processing parameters optimization of draw frame for rotor spun yarn strength using gene expression programming (GEP)

Breaking strength is one of the most important mechanical property of a yarn as it is the main parameter for quality control. This property depends on many different factors namely, raw material factors, process variables and machine parameters. Since, there is a high degree of interaction between yarn properties and influencing factors therefore, optimal processing conditions can not be determined easily. This article proposes prediction approach for the determination of the breaking strength of the yarn using gene expression programming (GEP) and optimization technique using MATLAB software. A nonlinear mathematical function was derived on the basis of draw frame variables that were distance between back and middle rolls, delivery speed and break draft by GEP. Afterward, optimal conditions were found in such a way that breaking strength to be maximized. Study showed that, optimal processing parameters including distance between back and middle rolls, break draft and delivery speed were respectively, 10.70 mm, 1.90 and 541.51 m/min (687.95 or 721.32 based on the optimization procedure).     

Preparation and characterization of carboxymethyl cellulose nonwovens by a wet-laid process

In this study, micro-porous carboxymethyl cellulose (CMC) nonwovens were prepared by carboxymethylation of cellulose nonwovens produced by a wet-laid process and their properties were investigated for potential applications as adhesion prevention barriers. After carboxymethylation, the thickness and mean pore size of the cellulose nonwovens were increased, whereas their pore size distribution became narrower. Tensile strength of cellulose nonwovens was proportional to basis weight, and dramatically increased after carboxymethylation. CMC nonwovens immediately absorbed a phosphate buffered saline solution and showed swollen phase within 1 min. It was found that the thickness and pore size distribution of CMC nonwovens could be easily controlled by the wet-laid process. It is expected that the CMC nonwovens can be used as adhesion prevention barriers.     

Preparation and characterization of cellulose nanofiltration membrane through hydrolysis followed by carboxymethylation

Bamboo cellulose (BC) is hydrophilic, biodegradable and inexhaustible. The bamboo cellulose membrane (BCM) is one of the best materials to replace petroleum-based polymer film for water purification. In this study, the N-methylmorpholine-N-oxide (NMMO) was used as a solvent to dissolve cellulose 6 wt.%, and regenerated cellulose membrane was prepared by phase inversion. A new kind of cellulose nanofiltration membrane (BC-NFM) was obtained by the hydrolysis and carboxymethylation of dense cellulose membrane (BCM). The modification was carried out through hydrolysis followed by carboxymethylation. The BC-NFM was characterized by XRD, FT-IR, SEM and thermal analysis. BC-NFM performance evaluation instrument were used to evaluate retention rate and water flux of nanofiltration membrane. BCM was immersed in 1 mol/l NaOH and 3 wt/v.% chloroacetic acid solution to obtain BC-NFM. By calculating, pore size of nanofiltration membrane was 0.63 nm. With a pressure of 0.5 MPa, the water flux of nanofiltration membrane for Na₂SO₄ solution was 10.32 l/m²h, and the retention rate was 68.4 %. The water flux for NaCl solution was 13.12 l/m²h, and the retention rate was 34.9 %. And the retention rates were 93.0 % and 98.9 % for methyl orange and methyl blue, respectively. The stability of the nanofiltration membrane was measured by the thermal analyzer, following the order of BC>BCM>BC-NFM. The prepared cellulose nanofiltration membrane exhibited good stability in water treatment process, and can be used to remove organic compounds in aqueous solutions.     

Effect of chemical softening of coconut fibres on structure and properties of its blended yarn with jute

Coconut fibres were subjected to chemical treatment to obtain softer and finer fibres, suitable to blend with other finer fibre like jute. The chemical softening recipe was optimized using Box-Behnken design of experiments as 40 % Na₂S, 10 % NaOH and 6 % Na₂CO₃, which notably reduced the fineness (33 %) and flexural rigidity (74 %) and improved tensile property of coconut fibre. Effect of softening of coconut fibre on its process performance was studied in high speed mechanized spinning system at different blend ratios with jute. Blending with jute assists in spinning of coconut fibre to produce yarn of 520 tex at production rate of 5-6 kg/h, as compared to 15 kg/day for hand spun 5300 tex raw coconut fibre yarn in manual system. Analysis of blended yarn structure in terms of packing density, radial distribution of fiber components (SEM) and mass irregularity were investigated. SEM shows yarns made from softened coconut fibre -jute blends are more compact than raw coconut fibre -jute blend yarns. Coconut fibres were preferentially migrated to core of the yarn. Major yarn properties viz., tensile strength, and flexural rigidity of raw and chemically softened blended yarns were compared against their finest possible 100 % coconut fibre yarn properties. Yarn made up to 50:50 chemically softened coconut fibre-jute blend showed much better spinning performance, and having superior property in terms of reduced diameter, higher compactness, strength, initial modulus and less flexural rigidity than 100 % raw, 100 % chemically softened coconut fibre rope, and raw coconut fibre-jute blend yarns.     

Analysis and tensile characterization of air-entangled textured polyester woven fabrics depending on interlacement and yarn sets

The aim of this study was to understand the failure mechanism of two dimensional dry fabric structure considering yarn sets and interlacements. For this purpose, data generated on air-entangled textured polyester woven fabric under the simple tensile load and analyzed by developed regression model. The regression model showed that warp and weft directional tensile strengths of satin fabric were higher than those of plain and rib fabrics in unravel sample. This might be related to the number of interlacements of the fabrics. There was not a considerable difference between warp directional tensile strength of ravel and unravel satin fabrics, whereas weft directional tensile strength of ravel satin fabric decreased rapidly with respect to its unravel form. The satin fabric showed the highest warp directional tensile strength among the others. The lowest weft directional tensile strength was received from ribs fabric. In semi-ravel sample, all fabrics showed low warp and weft directional tensile strength values except in plain fabric. Warp directional tensile elongation of plain fabric was the highest in unravel sample. Satin fabric showed the highest warp directional tensile elongation in the ravel sample. Warp directional tensile elongations of all the fabrics in the semi-ravel sample became low. Weft directional tensile elongation of satin fabric was the highest in unravel sample. In addition, satin and plain fabrics showed the highest weft directional tensile elongations in the ravel sample. Weft directional tensile elongations of all the fabrics in the semi-ravel sample became low except in ribs fabric.     

Preparation and characterization of PVA/PU blend nanofiber mats by dual-jet electrospinning

A series of blend nanofiber mats comprising poly(vinyl alcohol) (PVA) and polyurethane (PU) were prepared by dual-jet electrospinning in various parameters. Orthogonal experimental design was used to investigate how those parameters affected on fiber diameters and fiber diameter distribution. Altogether three parameters having three levels each were chosen for this study. The chosen parameters were tip-to-collector distance (TCD), voltage and tip-to-tip distance (TTD). Fiber diameters, thermal properties, mechanical properties and hydrophilicity of the blend nanofiber mats were examined by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), tensile test, contact angle and water absorption test, respectively. The results showed that the optimum conditions for PVA/PU blend nanofiber mats fabricated by dual-jet electrospinning were TCD of 20 cm, voltage of 18 kV and TTD of 4 cm. Besides, the thermal stability of PVA/PU blend nanofiber mats had been improved compared with pure nanofibers. Furthermore, the elongation and tensile strength of the blend nanofiber mats were significantly increased compared with pure PVA and pure PU, respectively. And the blend nanofiber mats exhibited well hydrophilicity.