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Polycaprolactone nanofibers were prepared using five different solvents (glacial acetic acid, 90% acetic acid, methylene chloride/DMF 4/1, glacial formic acid, and formic acid/acetone 4/1) by electrospinning process. The effect of solution concentrations (5%, 10%, 15% and 20%) and applied voltages during spinning (10 KV to 20 KV) on the nanofibers formation, morphology, and structure were investigated. SEM micrographs showed successful production of PCL nanofibers with different solvents. With increasing the polymer concentration, the average diameter of nanofibers increases. In glacial acetic acid solvent, above 15% concentration bimodal web without beads was obtained. In MC/DMF beads was observed only at 5% solution concentration. However, in glacial formic acid a uniform web without beads were obtained above 10% and the nanofibers were brittle. In formic acid/acetone solution the PCL web formed showed lots of beads along with fine fibers. Increasing applied voltage resulted in fibers with larger diameter.

In this paper, surface of novel biosorbent (Canola hull) was characterized and its dye removal ability at different cationic dye concentrations was studied. The isoelectric point, functional groups and morphology of Canola hull were investigated as biosorbent surface characteristics. Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and UV–Vis spectrophotometry were used. Basic Blue 41, Basic Red 46 and Basic Violet 16 were used as model textile cationic dyes. The presence of functional groups onto Canola hull were investigated using FTIR. The intraparticle diffusion, pseudo-first order and pseudo-second order kinetic models were examined to evaluate the kinetic data and the rate constants were calculated. The Langmuir, Freundlich and Tempkin adsorption isotherm models were applied to describe the equilibrium isotherms. Thermodynamic parameters such as free energy, enthalpy and entropy of dye adsorption were obtained. The FTIR spectrum proved the presence of functional groups such as hydroxyl and amino groups in adsorbent surface. Adsorption kinetic of dyes followed pseudo-second order kinetics. The thermodynamic studies showed that the dye adsorption onto Canola hull is spontaneous, endothermic and physical reaction. The results indicated that Canola hull could be used as a noval natural biosorbent for the removal of cationic dyes.

In this paper, the preparation, characterization and dye adsorption properties of novel biocompatible composite (Chitosan-zinc oxide nanoparticle) (CS/n-ZnO) were investigated. Zinc oxide nanoparticles were immobilized onto Chitosan. Physical characteristics of CS/n-ZnO were studied using Fourier transform infra-red (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and wavelength dispersive X-ray spectroscopy (WDX). Two textile dyes, Direct Blue 78 (DB78) and Acid Black 26 (AB26), were used as model compounds. The effect of CS/n-ZnO doses, initial dye concentration, salt and pH were elucidated at 20+/-1 degrees C. The isotherm and kinetics of dye adsorption were studied. The presence of functional groups such as hydroxyl, amino and carbonyl groups were detected. Results showed zinc oxide nanoparticles were immobilized onto Chitosan. The data were evaluated for compliance with the Langmuir, Freundlich and Tempkin isotherm models. It was found that AB26 and DB78 followed with Langmuir and Tempkin isotherms, respectively. In addition, adsorption kinetics of both dyes was found to conform to pseudo-second order kinetics. Based on the data of present investigation, one could conclude that the CS/n-ZnO being a biocompatible, eco-friendly and low-cost adsorbent might be a suitable alternative for elimination of dyes from colored aqueous solutions.

Weak binding of chitosan on the wool constitutes the main problem in its application. In this paper, the surface modification of wool fabric using anhydrides to graft the chitosan was studied. Weight gain, antibacterial and antifelting properties of the chitosan grafted-acylated wool fabric were investigated. Wool fabrics were acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), using different solvents (dimethylsulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of wool were investigated. Chitosan was grafted to the acylated wool and the effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated wool were evaluated. Fourier transform infra-red (FTIR), scanning electron microscope (SEM), differential scanning colorimetry (DSC) and weight gain analyses provided evidence that chitosan was grafted on to the acylated wool through the formation of new covalent bonds. The grafted samples have antibacterial potential due to existence of the antibacterial property of chitosan. In addition, the chitosan grafted-acylated wool samples have antifelting property. The findings of this research support the potential production of new environmentally friendly textile fabrics.

In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N , N -dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.

A series of novel monoazo disperse dyes based on N -ester-1,8-naphthalimides were synthesized using 4-amino- N -methylglycinate-1,8-naphthalimide and 4-amino- N -ethylglycinate-1,8-naphthalimide, as diazo components, with various couplers. The spectrophotometric properties of the dyes were examined in different solvents and their solvatochromism effects were investigated. The dyes displayed λ max of between 515 and 563 nm and the molar extinction coefficient of the dyes varied from 25,863 to 49,080 l mol −1 cm −1 . Most of the dyes showed acceptable build up properties on polyester fibres under high temperature conditions and displayed moderate light fastness and very good wash and dry heat fastness on polyester fibres. The results indicated that the presence of an ester group within the dye molecule provided alkali-clearable potential.

Adsorption of cationic textile dyes namely, C.I. Basic Blue 41 and C.I. Basic Red 18 onto granular activated carbon (GAC) and silkworm pupa (SWP – a natural adsorbent) has been investigated for single and binary solute systems. Equilibrium isotherms were conducted for two, single solute systems and three binary combinations of the dyes. Although adsorption of C.I. Basic Red 18 on SWP showed no correlation with the Langmuir, Freundlich or Myers models, the Freundlich equation described the adsorption of Basic Blue 41 well and the Myers equation correlated reasonably well the two dyes on GAC. Of the multi-component models studied, the ideal adsorbed solution theory (IAST) gave reasonable predictions of the binary systems of the dyes on GAC but it failed to predict the binary system on SWP. The adsorption on SWP was shown to occur by chemisorption which was not affected by the presence of molecular oxygen.

Chitosan-poly (vinyl alcohol) (Cs: PVA) (2:3) and poly (caprolactone)-chitosan-poly (vinyl alcohol) (PCL: Cs: PVA) (2:1:1.5) nanofibrous blend scaffolds were fabricated using the electrospinning technique in the authors' previous studies. The results of the previous studies confirmed the high biological properties of the scaffolds and their ability in healing of burn and excision wounds on rat model. In the present study, the biological scaffolds were applied on diabetic dorsum skin wounds and diabetic foot wound on rat models (n = 16). Macroscopic and microscopic investigations were carried out using digital images and haematoxylin and eosin (H&E) staining respectively, to measure the wound areas and to track wound healing rate. It was found that at all time points the areas of wounds treated with nanofibrous scaffolds were smaller compared with the controls. Pathological results showed much better healing efficacy for the test samples compared with the control ones. Pathological investigations proved the presence of more pronounced granulation tissues in the scaffold-treated wounds compared with the control ones. At 20 days post excision, the scaffold-treated groups achieved complete repair. The results indicated that Cs: PVA and PCL: Cs: PVA nanofibrous webs could be considered to be promising materials for burn, excision and diabetic wounds healing.

The molecular interactions of polyacrylonitrile (PAN) and cellulose acetate (CA) were investigated thoroughly via dilute solution viscometry in dimethylformamide (DMF) as a common solvent at 30°C. The intrinsic viscosities and viscometric interaction parameters were experimentally determined for both binary (polymer/ dimethylformamide) and ternary (PAN/CA/dimethylformamide) systems. As all investigated PAN/CA ternaries evidenced negative viscometric interaction parameter values (δb & δk

The role of dodecyltrimethylammonium bromide (DTAB) and a series of gemini cationic surfactants in the adsorption rate of methylene blue (MB) on acrylic fibres has been studied by means of TOC, UV–vis and FT-NMR spectroscopy. The influence of surfactant concentration, alkyl chain and spacer length of geminis has been investigated at different temperatures. The dye adsorption rate increases with increasing temperature, while the retarding action of gemini cationic surfactants is much stronger than that of the corresponding monomeric surfactants. There are small differences among the geminis with the same alkyl chain but with various spacer lengths.

Five novel monoazo disperse dyestuffs based on N-ester-1,8-naphthalimide were synthesized. Acenaphthene was nitrated, then oxidized to 4-nitro-1,8-naphthalic anhydride. 4-Nitro-1,8-naphthalic anhydride was reacted with methyl and ethyl glycinate in alcoholic media, followed with reduction. 4-Amino-N-methyl and ethyl glycinate-1,8-naphthalimide were obtained. These products were diazotized and coupled with appropriate aromatic amines to give bluish-red or violet dyestuffs. All intermediates and dyestuffs were purified and characterized by 1H-NMR, FTIR, DSC, UV-VIS and Elemental Analysis. Dispersion of dyestuffs was prepared in water and applied to polyester fabrics. The dyed fabrics showed that four of the synthesized dyestuffs were suitable for coloring polyester fibers, producing deep bluish red with very good build up properties.

The radiation-induced graft copolymerization is an effective method for modification of the chemical and physical properties of polypropylene. Graft copolymerization of styrene onto polypropylene fibers has been studied by simultaneous irradiation method, using a 10 MeV electron beam. Samples were irradiated in an environment of nitrogen gas. The effects of radiation dose and styrene concentration in methanol, on the grafting yield were investigated. The effects of polyfunctional monomer, i.e., trimethylopropane trimethacrylate (TMPTMA) and acid (sulfuric acid) on the grafting yield were also examined. The grafted samples were then sulfonated and allowed to react with solution of a basic dye. The samples were characterized by mechanical properties and thermal stability. The mechanical properties of the radiated samples were reduced and the grafted samples had lower mechanical properties.

The interactions of two anionic azo dyes, Methyl Orange (MO) and Congo Red (CR), with a series of gemini cationic surfactants and dodecyl trimethyl ammonium bromide (DTAB) in aqueous solution have been investigated by means of UV–Vis spectroscopy. It was observed that the aggregation of surfactant and dye takes place at surfactant concentrations far below the critical micelle concentration of the individual surfactants. Aggregations with anionic dyes were reflected by hypsochromic shifts with a decrease in the intensity of absorption band. Further addition of surfactant results in an absorption spectrum of the dye characteristic in the presence of cationic micelles. The results also show bathochromic shifts for MO followed by sharp increase in intensity of the absorption bands at λmax after the CMC points of these surfactants. Such a behavior is observed for CR solutions in higher surfactant concentrations. The inhibiting effect of cationic surfactants on dyeability of cotton fabric with CR has also been studied at three different temperatures (30, 50, 90–92 °C). Results show large differences between DTAB and gemini cationic surfactants.

In this paper, the modification of nickel ferrite nanoparticles with cationic surfactant [cetyltrimethyl ammonium bromide (CTAB)] and its capability as a magnetic adsorbent for the removal of direct dyes (Direct Red 31, Direct Red 81, and Direct Red 80) from textile wastewater have been investigated. The Fourier-transformm infrared (FTIR) analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) images, and the determination of isoelectric point (pH at point of zero charge), were used to analyze the morphology to characterize the synthesized magnetic adsorbent. The effect of operating parameters including pH, initial dye concentration, adsorbent dosage, and inorganic salts on the dye removal efficiency was studied. The results showed that varying the pH of solution did not affect the dye removal efficiency. It was also concluded that by increasing the adsorbent dosage the available adsorption sites and the dye removal efficiency would increase. Adsorption isotherms such as Langmuir...

Fibers containing both polyacrylonitrile (PAN) and cellulose acetate (CA) were prepared through wet-spinning by using N,N-dimethylformamide (DMF) as a solvent. Compatibility of PAN and cellulose acetate blend (PCB) fibers was investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and infrared (IR) spectrophotometry. The absorptive capacity and mechanical properties of the fibers were measured. It was observed that the surface and the cross section of PAN fibers were quite smooth and free from voids and microcracks, whereas cracks and voids were present on the surface and cross section of blend fibers, which increased with the incorporation of CA in the blend. Moisture regains of blend fibers were quite high while their tensile properties showed a partial decrease. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2000–2005, 2007

Silk is a highly valued animal fibre that has long been used to produce textiles of the finest quality. During the degumming process it losses almost 30% of its weight. The weighting of silk fibres with mineral compounds is an effective technique to counteract this loss in weight. Chemical modification by graft copolymerization of vinyl monomers is also effective. Persian silk yarn was degummed using Marseille solution soap and graft copolymerized with 2-hydroxyethyl methacrylate (HEMA) in aqueous media by a redox initiator system. The percentage of HEMA in the feed varied from 0-100%. The grafting efficiency obtained was 70-90%. The pH of the medium varied and its effect on the graft copolymerization was investigated. The grafted silk yarn gained in weight as the pH of the copolymerization medium was reduced and the time of copolymerization increased. Grafting affects the mechanical properties of yarn by reducing the tensile strength and slightly increasing the elongation of the yarn. The solubility in a...

Polyacrylonitrile is an important polymer that is widely used in the manufacture of synthetic fibers, particularly for applications in apparel. Although a vast amount of literature is available on the polymerization process of acrylonitrile (AN) with other monomers, there are few reports of studies on polymerization in a mixed solvent of water with an organic solvent. It is conceivable that this method could combine the advantages of the solution and suspension polymerization methods. Synthesis of AN copolymers with two vinyl acids, methacrylic acid (MAA) and itaconic acid (IA), is carried out by solvent–water suspension polymerization. The polymerizations are performed with an equal ratio mixture of dimethylformamide as a solvent and water as a nonsolvent at 60°C using α,α-azobisisobutyronitrile as an initiator. The kinetics of polymerization are studied by plotting the conversion versus reaction time for different mole ratios of AN with vinyl acids. Copolymers are characterized by FTIR and capillary viscometery. The results show that IA depresses the rate of polymerization more than MAA in this reaction medium, and this effect becomes more significant at higher vinyl acid mole ratios. High conversion in a short reaction time is obtainable for copolymers with a low vinyl acid mole fraction. However, for mole ratios of more than 93:7, the rate of the reaction is drastically reduced and low conversion (

Acrylic fibers are among the most useful synthetic fibers for textile applications, and special acrylic fiber (SAF) has industrial applications. The physical and mechanical properties of fiber are affected by several parameters; one such parameter is coagulation conditions: bath temperature, bath composition, and drawing. Acrylonitrile–carboxylic acid copolymers, that is, acrylic methacrylic and itaconic acid, were converted into fibers using the dry-jet wet spinning technique. The coagulation bath temperature was varied from 5°C to 35°C, and the properties of the fibers so obtained were investigated. The effect of the final drawing ratios (6.5 and 8.5) on such physical and mechanical properties as tenacity, sonic modulus, initial modulus, density, crystallinity index, and X-ray orientation were also investigated. In addition, thermogravimetric analysis and scanning electron microscopy were used to determine the thermomechanical properties and fracture morphology of the fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1825–1837, 2003

Polyacrylonitrile (PAN) and copolymer of acrylonitrile–vinyl acids prepared by solution polymerization technique have been characterized by Differential Scanning Calorimetry (DSC) (under dynamic as well as isothermal conditions), themograviemetric analysis (TGA), and on-line DSC-FTIR spectroscopy. The DSC of copolymers was carried out at 5°C/min in nitrogen and air. In nitrogen atmosphere the DSC exotherm show a very sharp peak, whereas, in air atmosphere DSC exotherm is broad, and starts at a much lower temperature compared to what is observed in nitrogen atmosphere. The initiation temperature of PAN homopolymer is higher than that for the copolymers. For instance, the initiation temperature of PAN in air is 244°C, whereas, the onset of exothermic reaction is in the range of 172 to 218°C for acrylonitrile–vinyl acid copolymers. As the vinyl acid content increases the ΔH value reduces. The ΔH value of PAN in air was 7025 J/g, whereas, for P(AN-AA) with 5.51 mol % of acid it was 3798 J/g. As the content of acrylic acid comonomer is increased to 17.51 mol % the value of ΔH decreases further to 1636 J/g. The same trend was observed with MAA and IA as well. DSC-FTIR studies depict various chemical changes taking place during heat treatment of these copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 685–698, 2003

Outstanding wound healing activity of gum tragacanth (GT) and higher mechanical strength of poly (e-caprolactone) (PCL) may produce an excellent nanofibrous patch for either skin tissue engineering or wound dressing application. PCL/GT scaffold containing different concentrations of PCL with different blend ratios of GT/PCL was produced using 90% acetic acid as solvent. The results demonstrated that the PCL/GT (3:1.5) with PCL concentration of 20% (w/v) produced nanofibers with proper morphology. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were utilized to characterize the nanofibers. Surface wettability, functional groups analysis, porosity and tensile properties of nanofibers were evaluated. Morphological characterization showed that the addition of GT to PCL solution results in decreasing the average diameter of the PCL/GT nanofibers. However, the hydrophilicity increased in the PCL/GT nanofibers. Slight increase in melting peaks was observed due to the blending of PCL with GT nanofibers. PCL/GT nanofibers were used for in vitro cell culture of human fibroblast cell lines AGO and NIH 3T3 fibroblast cells. MTT assay and SEM results showed that the biocomposite PCL/GT mats enhanced the fibroblast adhesion and proliferation compared to PCL scaffolds. The antibacterial activity of PCL/GT and GT nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa was also examined.

Solution copolymerization of acrylonitrile (AN) with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using α,α′-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012–0.092 mol %. Copolymers were characterized by FTIR, CHN analysis, 1H-and 13C-NMR, and viscometry. The reactivity ratios were calculated using Fineman–Ross and Kelen–Tudos methods. In all three systems, the value of r1 (AN) is much less than the value of r2. However, the r2 (MAA) is higher than r2 of (AA) and (IA). The reactivity ratios were calculated using Q and e schemes also. The results are in good agreement with experimentally calcualted data. The tacticity and sequence length distribution of these copolymers were calculated using 13C-NMR from CN and CH signals. It was observed that the isotacticity of acrylonitrile–itaconic acid copolymer P(AN–IA) with 8.2 mol % of a comonomer is lower than that of P(AN–MAA) with 10.3 mol % and P(AN–AA) with 7.61 mol %. © 1996 John Wiley & Sons, Inc.

Feldspar/titanium dioxide/chitosan hybrid, a photoactive biocompatible adsorbent for anionic dyes, was synthesized, char- acterized, and successfully tested. The adsorbent characterization, pH role, adsorbent dose effect, equilibrium data, kinetic plats, and thermodynamic parameters are reported. The point of zero charge for the hybrid was measured to be 8.3, and the most favorable pH range for the adsorption process was found to be below this pH value. The adsorption equilibrium study demonstrated that the Freundlich model was best fitted to the experimental data. Without UV light exposure, the prepared adsorbent adsorbed 72 mg of Acid Black 1 (AB1)/g of sorbent (86% removal) from a 100-mL solution with an initial dye concentration of 50 mg/L, whereas UV irradiation resulted in an increase in the elimination of AB1 dye (97% removal). The kinetic data was depicted well by the pseudo- second-order model. The thermodynamic parameters indicated that the reaction between the hybrid and the dye was exothermic and also spontaneous at lower temperatures. In the batch desorption process, several aqueous solutions adjusted to different pH values were tested, and the best desorption performance (90% desorption) was achieved at pH 11. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40247.

Graft copolymerization of acrylic acid (AA) onto Poly(ethylene terephthalate) (PET) fabrics with the aid of benzoyl peroxide was carried out. The effect of polymerization parameters on the graft yield was studied. Percent grafting was enhanced significantly by increasing benzoyl peroxide (BP) concentrations up to 3.84 g/lit and then decreased upon further increase in initiator concentration. Preswelling of PET leads to changes in its sorption-diffusion properties and favors an increase in the degree of grafting. The antibiotics treated grafted fabrics showed antibacterial properties towards gram-positive and gram-negative microorganisms. FTIR and SEM were used to characterize AA-grafted polyester fabrics.

In this work the use of silkworm pupa, which is the waste of silk spinning industries has been investigated as an adsorbent for the removal of C.I. Basic Blue 41. The amino acid nature of the pupa provided a reasonable capability for dye removal. Equilibrium adsorption isotherms and kinetics were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that adsorption behavior of the dye could be described reasonably well by either Langmuir or Freundlich models. The characteristic parameters for each isotherm have been determined. The monolayer adsorption capacity was determined to be 555 mg/g. Kinetic studies indicated that the adsorption follows pseudo-second-order kinetics with a rate constant of 0.0434 and 0.0572 g/min mg for initial dye concentration of 200 mg/l at 20 and 40 °C, respectively. Kinetic studies showed that film diffusion and intra-particle diffusion were simultaneously operating during the adsorption process. The rate constant for intra-particle diffusion was estimated to be 1.985 mg/g min 0.5 .

Solid-state polymerisation (SSP) is a convenient method of producing high molecular weight polymers at relatively low temperatures. In this work the SSP of nylon-6 was examined in a fixed-bed reactor. The solid-state polymerisation reaction kinetics of Nylon-6 was investigated in connection with the relative viscosity (RV) of the initial starting materials. The changes in the molecular weight and other properties were monitored as a function of the reaction times at solid-state temperatures of 130–200 °C. Starting materials with higher initial molecular weights exhibited higher rates of SSP than those with lower initial values. Activation energies decreased at temperatures above 170 °C, and this indicated a change in the SSP reaction mechanism. At temperatures of 170–200 °C similar activation energies were required for the polymerisation of all samples.