Preparation of poly(acrylonitrile)-grafted silk fibers with antibacterial properties

This study is focused on investigating the feasibility of using silver(I) ions loaded poly(acrylonitrile)-grafted silk fibers as antibacterial dressing material. The optimum grafting conditions for ceric ammonium nitrate induced graft-copolymerization of acrylonitrile onto silk fibers were found to include initiator concentration of 35 mM, catalyst HNO₃ concentration of 0.40 M and initiation time of 10 min. The poly(acrylonitrile)-grafted silk fibers were loaded with silver(I) ions by equilibration method. The resulting fibers were investigated for their biocidal action against E. coli, by using zone inhibition and colonies counting method.     

Structure and performance of<Emphasis Type="Italic">Bombyx mori</Emphasis> silk modified with nano-TiO<Subscript>2</Subscript> and chitosan

Bombyx mori (B. mori) silk was modified with the nano-TiO₂ and chitosan dispersion system by the crosslinking reactions of citric acid (CA) and maleic anhydride (MA). The average size of the nano-TiO₂ particles in the aqueous dispersion system was 36.7 nm. The scanning electron microscopy (SEM) micrographs showed that the nano-TiO₂ particles were spherical and homogeneously dispersed in the dispersion system, and the surface ofB. mori silk fiber treated with the nano-TiO₂ and chitosan dispersion system was rougher than that of the untreated one. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) Spectrometry indicated that the crystallinity of theB. mori silk fiber increased after treatment. It was also found that the nano-TiO₂ and chitosan contributed to significantly enhance the mechanical properties including breaking strength, breaking elongation, initial modulus, rupture work, and elastic recovery property of theB. mori silk fiber. The wrinkle-resistant performance of the treatedB. mori silk fabrics was also greatly improved.     

An adsorption study of alum-morin dyeing onto silk yarn

Silk yarn was dyed with morin (2′,3,4′,5,7-pentahydroxyflavone) by using alum as mordant. In order to optimize the process, three methods of dyeing involving: pre-mordanting, simultaneous mordanting, and post-mordanting were assessed and compared with a mordant-free process. The adsorption of alum-morin dye onto silk fibers indicated that the adsorption capacities were significantly affected by pH, the initial dye concentration, and temperature. The initial dye adsorption rates of alum-morin dye on silk before equilibrium was reached increased with higher dyeing temperatures. The pseudo second-order kinetic model was indicated for alum-morin dyeing (simultaneous mordanting) of silk at pH 4.0 with an activation energy (E _a ) of 45.26 kJ/mol. The value of the enthalpy of activation (ΔH ^#) for alum-morin dyeing on silk at pH 4.0 was −31.29 kJ/mol. Also, the free energy (ΔG ^o) and entropy changes (ΔS ^o) for alum-morin dyeing on silk were −17.73 kJ/mol and −45.7 J/molK, respectively, consistent with a spontaneous and exothermic adsorption process.     

Fusarium proliferatum侵染玉米花丝的解剖学研究

层出镰刀菌(Fusarium proliferatum)分生孢子喷洒在玉米花丝上,可侵入玉米柱头的茸毛细胞、表皮细胞以及花丝的表皮细胞,菌丝沿花丝的薄壁组织细胞、维管束细胞向子房方向生长。F.proliferatum侵染花丝后,导致花丝薄壁细胞、表皮细胞皱缩,花丝萎缩变形。结果显示,F.proliferatum可直接侵染玉米花丝,借助花丝通道侵入玉米雌穗,花丝通道是F.proliferatum侵染玉米雌穗的途径之一。     

Polyaniline-doped TiO<Subscript>2</Subscript>/PLLA fibers with enhanced visible-light photocatalytic degradation performance

A simple and practical strategy has been developed for preparing polyaniline(PANi)-doped TiO₂/poly(l-lactide) (P@TiP-C) fibers by a combination of coaxial-electrospinning and in-situ polymerization. The TiO₂/PLLA composite fibers with TiO₂ located on the surface were fabricated by coaxial-electrospinning, with PLLA as the core phase and a dispersion of TiO₂ particles, a well-known photocatalyst, in the sheath phase. The aniline monomers were also located in the core phase and in-situ polymerized by ammonium persulfate (APS) after electrospinning. SEM images show that TiO₂ particles were located on the surface of PLLA fibers. Photocatalytic degradation tests show that the P@TiP-C fibers exhibit enhanced photocatalytic activity for degradation of methyl orange under visible light, likely due to the synergistic effect of PANi and TiO₂.     

Polyacrylonitrile/electroconductive TiO<Subscript>2</Subscript> nanoparticles composite fibers <Emphasis Type="Italic">via</Emphasis> wet-spinning

For the first time, novel polyacrylonitrile (PAN)/electroconductive TiO₂ (EC-TiO₂) nanoparticles composite fibers have been successfully spun via wet-spinning. The composite fibers had uniform diameter and homogeneous surface. Moreover, at low content of EC-TiO₂ nanoparticles, the composite fibers realized a transition from an insulator to a conductor. This work has provided a simple and effective avenue for the production of PAN/EC-TiO₂ nanoparticles composite fibers that have great potential applications in the antistatic textiles.     

Dyeing properties of Bombyx mori silks grafted by 2-hydroxyethyl methacrylate (HEMA)

Graft copolymerization technique was selected to improve properties of Bombyx mori silks. The silks were degummed and grafted by 2-hydroxyethyl methacrylate (HEMA), resulting in different graft yields of the degummed silks. It was found that thermal decomposition temperature and wear strength of the silks grafted by HEMA were clearly improved. In addition, dyeing properties of the degummed and HEMA-grafted silks were investigated by using different natural dyes, i.e. coconut shell (Cocos nucifera), pandanus (Pandanus odorus) and Siamese cassia (Cassia siamea) and also synthetic dyestuff, i.e. acid dye. When dyeability and colorfastness properties were investigated, it was observed that higher graft yield of the HEMA-grafted silks exhibited greater dye uptake for all of the applied dyes. Besides, fastness properties to washing, perspiration, light and rubbing of the degummed and HEMA-grafted silks were examined.     

Study on coloration of silk based on coupling reaction with a diazonium compound

This paper describes how coloration of silk can be achieved using a coupling reaction between a diazonium compound, made from Color Base Red G (C.I. 37105) and tyrosine residues in the silk protein fibroin. A pigment with an azo structure obtained from the reaction between the diazonium of Color Base Red G with p-methylphenol was synthesized and studied as a model compound for the coloration reaction. The colored materials were characterized using UV-vis, FT-Raman, FT-IR, ¹H-NMR, and mass spectroscopy. Both the colored silk and the model compound gave yellow colors with absorption maxima in the region of 400 nm. The results suggest that the use of coupling reactions could be developed into a dyeing method for protein fibers or other protein materials that contain tyrosine residues. Because the chromophores are incorporated into the protein chains, such dyed silks should have good wet fastness properties.     

The Use of Sumac as a Natural Mordant in Green Production of Iranian Carpet

Dyeing is a state-of-the-art realm of textile engineering, however, the emphasis on petroleum-based products is now shifting towards green fibers, particularly, green manufacturing processes. In the present work, a natural mordant, sumac, was extracted and used alone and in combination with alum (a mineral mordant) in silk fibers dyeing with madder and Reseda green dye to make the green production of Iranian carpet possible. The FT-IR ATR spectra of the washed, mordanted, and mordanted dyed silk fibers revealed bonding between silk fibers and green materials. The color of the silk fibers dyed with madder and Reseda extraction was quantified in terms of CIELab (L*, a*, and b*) and K/S values. The effects of different treatments on fastness properties including light, wash, and rubbing fastness were assessed by ISO standard test method.     

Performance of PTT fabric treated with CNTs/SiO<Subscript>2</Subscript>/thiazole dye hybrid materials

A series of CNTs/SiO₂/thiazole dye hybrid materials prepared via the sol-gel process is synthesized from carbon nanotubes (CNTs) and tetraethoxysilane with heteroaryl 4-phenyl-2-amino-thiazole dyes. Heterocyclic 4-phenyl-2-aminothiazole dyes are processed with the hydrolysis-condensation reaction at a constant ratio of vinyltriethoxysilane and tetraethoxysilane condensed with modified CNTs in appropriate proportion under a catalyst. The structures of the CNTs/SiO₂/thiazole dye hybrid materials are characterized by Fourier transform infrared spectroscopy (FTIR). Polytrimethylene terephthalate (PTT) fabrics are used to evaluate the morphology structure by scanning electron microscopy (SEM). SEM images show that a uniform dyeing on the PTT fabrics to confirm the reaction of hybrid materials with PTT fabrics. The washing fastness, color evenness, water contact angle, air permeability, electric conductivity, and weatherability of PTT fabrics dyed with CNTs/SiO₂/thiazole dye hybrid materials are evaluated, with results indicating improved conductivity and water-repellent.     

Performances of ramie fiber pretreated with dicationic imidazolium ionic liquid

The chemical structure of a new gemini dicationic imidazolium ionic liquid, 3,3′-[1,2-ethanediylbis (oxy-2,1-ethanediyl)]-bis[1-methyl-imidazolium]-dibromide (PEG₁₅₀-DIL) was established by ¹H-NMR and elemental analyses. Then, PEG₁₅₀-DIL was applied to pretreat ramie fiber. PEG₁₅₀-DIL treated ramie fiber was characterized by FT-IR, XRD, DSC-TG and FE-SEM. Finally, the mechanical and dyeing properties of PEG₁₅₀-DIL pretreated ramie fibers were studied. The optimum condition of PEG₁₅₀-DIL modification was carried out at 100 °C for 30 min. The color strength increased obviously with the duration time and temperature of the PEG₁₅₀-DIL. The tensile strength and strength retention of PEG₁₅₀-DIL -treated ramie fibers decreased with the increase of pretreating time and temperature. The tensile strength retention was 86.20 % under optimal PEG₁₅₀-DIL pretreating condition (100 °C, 30 min).     

Fabrication and characterization of nano Al<Subscript>2</Subscript>O<Subscript>3</Subscript> filled PVA:NH<Subscript>4</Subscript>SCN electrolyte nanofibers by electrospinning

Present paper reports a method of preparing polymer composite electrolyte nanofiber mat using polyvinyl alcohol (PVA), ammonium thiocynate (NH₄SCN) salt, and aluminium oxide (Al₂O₃) nano particles based on electrospinning technique. Two-stage process of preparation of nanofibers, namely, preparation of nano particles filled PVA electrolyte gel solution followed by its electrospinning has been used. The so obtained nanofibers have been characterized by XRD, DSC, SEM, and Conductivity measurements. XRD patterns affirm the formation of nanocomposite while SEM pictures reveal formation of fibers on a nano scale format (300–800 nm). Fibers of the electrolytes are seen to be thermally stable. Ionic conductivity of electrolyte fiber is seen to improve in the presence of nano filler at room temperature with a maximum at 5.31×10⁻³ Scm⁻¹ for 4 wt% filler concentration, which is comparable to that for corresponding dried gel electrolyte films.     

Modification and Characterization of Nano-TiO<Subscript>2</Subscript> for Efficient Fixation on Cotton Fibers

In this paper, a silane coupling agent, 3-aminopropyltriethoxysilane, was reacted with nano-TiO₂ to introduce amino group onto it which was then reacted with trichlorotriazine to obtain a dichlorotriazine functionalized nano-TiO₂ for the firm fixation of it on cotton fibers. The reaction process was monitored by the titration of primary and secondary amino groups, and the reaction conditions were optimized with orthogonal method accordingly. The dichlorotriazine functionalized nano-TiO₂ was reacted with cotton fabric by the nucleophile substitution reaction to afford nano-TiO₂ functionalized cotton fabric, the structure and surface morphology of the nano-TiO₂ finished cotton fibers were studied by FT-TR and SEM. In addition, the fixation duration of the nano-TiO₂ modified cotton was studied according to AATCC test method 61–2010. The results show that the washing fastness of the nano-TiO₂ is excellent.     

The effects of electrical discharge on the mechanical properties of <Emphasis Type="Italic">Bombyx mori</Emphasis> silk fibroin

Bombyx Mori is a representative of natural fibers which is known for its mechanical stability. In this study, electrical discharge of the fibers exposed to different voltages for certain periods was examined and mechanical lifetime was measured and also the structure parameters U _o and γ were calculated. We observed that crosslinks might be formed at the silk fibers exposed to high voltages and as a result, fibers become more resistant to mechanical effects.     

Preparation of Cu-BTC/PVA Fibers with Antibacterial Applications

In this study, a metal-organic framework (MOF)/polymer electrospun fiber was prepared. The MOF, copper-1,3,5- benzenetricarboxylate (Cu-BTC), was synthesized using a sonochemical method at 25 °C, with a 1:1:1 mixture of dimethylformamide, ethanol, and deionized water as solvent. The sonication time was shown to have a pronounced effect on the morphology and structure of the Cu-BTC. A square pyramid shape with sides of 100 nm was obtained after 2 h of sonication. Extending the sonication time provided a lower amount of unknown phase and produced a uniform Cu-BTC framework. The Cu-BTC-modified PVA fibers were then fabricated by electrospinning. The effect of the Cu-BTC and PVA concentration was investigated at 25 kV, a flow rate of 10 μl/min, and a working distance of 150 mm. FTIR spectra and FESEM images showed good dispersion of the Cu-BTC on the PVA fiber. The as-prepared Cu-BTC-modified PVA fibers exhibited excellent antibacterial effectiveness against S. aureus.     

Unusual Microstructure and Mechanical Properties of Egg Case of the Bolas Spider <Emphasis Type="Italic">Mastophora corpulenta</Emphasis> Banks (Araneae,Araneidae)

Bolas spiders of the genus Mastophora are very uncommon orb-weaver spiders, famous for their unusual predatory behavior. Being strictly nocturnal and very cryptic, they are extremely difficult to reveal, which explains their rarity in world arachnological collections. After a recent finding of an adult female of Mastophora corpulenta Banks (one of especially rare representatives of the genus), a few egg cases of this species became available, which seem to be very different from those of more common spiders due to their unusual hardness and coloration. We characterized some spectral, structural, and mechanical properties of this unusual silk material, by using Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), 3D profilometer imaging, and atomic force microscopy (AFM). For comparison, similar studies were performed for egg cases of the Southern black widow Latrodectus mactans Fabricius, since spiders of the genus Latrodectus are known to produce silk fibers of comparable toughness. Some similarities were observed between the silks produced by Mastophora corpulenta and Latrodectus mactans in terms of the size and chemical composition of egg cases. At the same time, SEM imaging and AFM force characterization revealed striking differences between them, due to the fact that Mastophora egg cases, unlike those produced by more common Araneae species, includes a solid (fused) wall, lacking evident porous structure, which results in their outstanding stiffness and strength.     

Preparation and characterization of inner-pressure hollow fiber composite membrane via two-way coating technique for CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> separation

High-selectivity inner-pressure hollow fiber composite (HFC) membrane for CO₂/CH₄ separation was prepared through the Two-way coating (TWC) technique. The blends of poly(vinylamine) (PVAm)/polyvinyl alcohol (PVA) were coated onto porous hollow fiber polysulfone (PSF) ultrafiltration (UF) membrane with an effective membrane area of 0.4 m². The effects of fabrication parameters on the permselectivity of the resultant HFC membrane were investigated and the optimum preparation conditions were obtained as follows: coating time for 30 min and air blowing time for 30 min after the coating. The prepared HFC membrane showed the typical characteristic of fixed carrier membrane with a high selectivity of CO₂ and CH₄: the separation factor of CO₂/CH₄ (40 vol% CO₂ at 25 °C and 0.2 MPa) was 36.6 and the CO₂ permeability was 56.3 GPU. Field emission scanning electron microscopy (FESEM) images indicated that the HFC membrane prepared by TWC technique had a uniform coating layer along the whole hollow fiber. Membrane permselectivity showed almost no difference between different membrane sections. The HFC membrane showed a good stability during the continuous testing process of 540 h. And the HFC membrane preserved at 30 °C and 40 % humidity exhibited a good durability with a basically unchanged separation factor after 30 days.     

Properties and performance of polypyrrole (PPy)-coated silk fibers

Different silk substrates in form of spun silk tops, nonwoven web, yarn, and fabric were coated with electrically conducting doped polypyrrole (PPy) by in situ oxidative polymerization from an aqueous solution of pyrrole (Py) at room temperature using FeCl₃ as catalyst. PPy-coated silk materials were characterized by optical (OM) and scanning electron (SEM) microscopy, FT-IR spectroscopy, and thermal analysis (DSC, TG). OM and SEM showed that PPy completely coated the surface of individual silk fibers and that the polymerization process occurred only at the fiber surface and not in the bulk. Dendrite-like aggregates of PPy adhered to the fiber surface, with the exception of the sample first polymerized in the form of tops and then spun into yarn using conventional industrial machines. FT-IR (ATR mode) showed a mixed spectral pattern with bands typical of silk and PPy overlapping over the entire wavenumbers range. DSC and TG showed that PPy-coated silk fibers attained a significantly higher thermal stability owing to the protective effect of the PPy layer against thermal degradation. The mechanical properties of silk fibers remained unchanged upon polymerization of Py. The different PPy-coated silk materials displayed excellent electrical properties. After exposition to atmospheric oxygen for two years a residual conductivity of 10–20 % was recorded. The conductivity decreased sharply under the conditions of domestic washing with water, while it remained essentially unchanged upon dry cleaning. Abrasion tests caused a limited increase of resistance. PPy-coated silk tops were successfully spun into yarn either pure or in blend with untreated silk fibers. The resulting yarns maintained good electrical properties.     

A new consolidation system for aged silk fabrics: Interaction between ethylene glycol diglycidyl ether,silk Fibroin and Artificial Aged Silk Fabrics

Consolidation of fragile historic silks is of great importance for further displays and researches. An effective and convenient method to consolidate aged silk fabric has been proposed by using a silk fibroin (SF)/ethylene glycol diglycidyl ether (EGDE) consolidation system. Artificial aged silk fabrics treated with SF/EGDE show great improvement in mechanical properties. The chemical reaction between EGDE and silk fabrics has been proved in previous paper. And in this paper, mechanical test, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrum (FTIR) test and amino acid analysis (AAA) were applied to illustrate the interactions between SF and silk fabric, EGDE and SF. Results show that SF takes part in the consolidation in the form of adhesions on the surface of silk fibers. The chemical reactions and film adhesion are both responsible for the improvements of mechanical properties in the consolidation.     

Dyeing and antibacterial properties of <Emphasis Type="Italic">Liriope platyphylla</Emphasis> fruit extracts on silk fabrics

Dyeing and antibacterial properties of a natural dye extracted from Liriope platyphylla fruit applied on silk fabrics have been studied. The total phenolic content (1109.13±69.02 mg), total flavonoid content (530.60±89.44 mg), and total anthocyanin content (492.26±77.79 mg) were measured in 100 g fresh weight of L. platyphylla fruits. In addition, ten anthocyanins and four flavanols were identified in L. platyphylla fruits by high performance liquid chromatography with diode array detection coupled with electrospray ionization mass spectrometry (HPLC-DAD/ESI-MS). A broad variation in color shade and color depth can be achieved with mixtures of dye extracts and metal mordants. Purple, blue, and pale green were main color shades of silk fabrics dyed with the extracts. The fastness of dyed silk fabrics except for control dyed fabrics against light, washing, and rubbing were acceptable with at least a grey scale rating of 3. The antibacterial activities of L. platyphylla fruit extracts were retained on dyed silk fabrics even after home washing 30 cycles. Mordanting with metal salt mordant had a positive effect on antibacterial activity of dyed silk fabrics in this study. Among them, aluminum and copper were the most effective mordants for improving antibacterial activity of silk fabrics dyed with L. platyphylla fruit extracts. The costs of natural dyeing of per silk fabrics kg by the extracts from L. platyphylla fruit were also calculated on laboratory scale.