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Abstract: We report here a highly durable electroless nickel plating on Kevlar fiber through iodine-aided palladium-free catalyzation process. Kevlar was first treated with an iodine–potassium iodide aqueous solution to impart iodide component into the near fiber surface. The doped iodine was converted to silver iodide particles by treatment with silver nitrate aqueous solution, and subsequently silver iodide was reduced to silver metal particles. After electroless plating, a smooth nickel layer was evenly deposited on the fiber surface, which was resistant against sonication, tape peel-off, and alkaline corrosion tests. The silver particles formed on and near the fiber surface act as an anchor for the plated layer as well as a catalyst for electroless plating. Further investigation revealed that the use of an anionic surfactant during the catalyzation process enhanced the adhesive force of the plated layer with fiber surface. The plated fibers possessed high tensile strength, electrical conductivity, and ferromagnetic properties. [Copyright &y& Elsevier]

Abstract: Highly adhesive metal plating was performed on poly(p-phenylene-2,6-benzobisoxazole) fiber named Zylon® via iodine pretreatment followed by electroless plating. First, iodine components were selectively doped into the inner part of the fiber near the surface through iodine vapor exposure. The doped iodine was converted to palladium iodide particles by treating with palladium chloride solution. After the reduction of the iodide to metal palladium particles, electroless copper plating was conducted on the fiber. A uniform copper layer was deposited on the fiber surface and exhibited high durability in durability tests such as ultrasonic exposure, tape peeling-off, and corrosion in NaCl solution. This durability was attributed to the palladium particles formed at the fiber surface that served as an anchor for the plated layer as well as an electroless plating catalyst. The plated fibers also possessed electrical conductivity. Although the tensile strength of the Zylon® fiber decreased from 5.8 to 4.9GPa after undergoing the pretreatment and plating processes, the light shielding effect improved the light resistance of the plated fibers in terms of tensile properties. After 18days of xenon lamp exposure, the plated fibers retained 74% of its initial strength, whereas that of untreated fibers decreased to 43%. [Copyright &y& Elsevier]

Abstract: Silver (Ag) nanowires were fabricated from silver chloride (AgCl) by the hydrothermal method. The successful formation of Ag nanowires relied on the low solubility of AgCl as a precursor and the structural change of glucose to polymer on the Ag nanowire (protective layer). The Ag+ ion concentration in the reaction solution containing AgCl was initially low, but after a reaction time of over 12h, Ag+ gradually reduced to Ag metal. Transmission electron microscope, Raman spectrometery, and X-ray photoelectron spectroscopy revealed that the surface of the obtained Ag nanowires possessed a carbon-rich layer with a carboxyl group, and the Ag+ ion coordinated with the carboxyl group of this layer. The difference in the surface-free energy of Ag crystals changed the crystal growth rate that impelled the anisotropic growth of the Ag particles. By examining various reaction conditions, it was determined that the ratio of Cl− to Ag+, reaction temperature, and reaction time are important factors for successful preparation of Ag nanowires. Under the reaction condition that the molar ratio of Cl− to Ag+ at 160°C for 24h is above equimolar concentration, uniform Ag nanowires were successfully prepared. [Copyright &y& Elsevier]

Abstract: Carbon fibers were prepared from silk fibers after an iodine treatment and the carbon yield, fiber morphology, structure and mechanical properties were investigated. A single or multi-step carbonization process was used for the preparation. In the single step process, silk fibroin (SF) fibers were heated from 25 to 800°C with a heating rate of 5°Cmin−1 under Ar atmosphere. However, the carbon fiber obtained was partially melted and was too fragile to handle. For better performance, SF fibers were treated with iodine vapor at 100°C for 12h and untreated and iodinated SF fibers were heated from 25 to 800°C by a multi-step carbonization process, which was defined based on the optimum thermal degradation rate of silk. In this multi-step process, the carbon fibers obtained from iodinated SF were structurally intact and stable in appearance, and the carbon yield achieved was ca. 36wt.%, much higher than the value for untreated SF. X-ray diffraction, Raman spectroscopy and transmission electron microscopic observation revealed that the obtained carbon fibers from both untreated and iodinated SFs had a basically amorphous structure. The strength of carbon fibers prepared from iodinated SF using the multi-step carbonization was considerably increased compared to that of untreated SF. According to viscoelastic measurement, by heating above 280°C the iodine introduced intermolecular cross-linking of the SF, and its melt flow was inhibited which produced a higher yield and better performance of the carbon fiber. [Copyright &y& Elsevier]

Abstract: The effect of the dispersion, ozone treatment and concentration of cup-stacked carbon nanotubes on mechanical, electrical and thermal properties of the epoxy/CSCNT nanocomposites were investigated. Ozone treatment of carbon fibers was found to increase the surface oxygen concentration, thereby causing the contact angle between water, epoxy resin and carbon fiber to be decreased. Thus, the tensile strength, modulus and the coefficient friction of carbon fiber reinforced epoxy resin were improved. Moreover, the dispersion of fibers in polymer was increased and the electrical resistivity was decreased with the addition of filler content. The dynamic mechanical behavior of the nanocomposite sheets was studied. The storage modulus of the polymer was increased by the incorporation of CSCNTs. But the glass transition temperature decreased with increasing fiber loading for the ozone treated fiber composites. The ozone treatment did affect the morphology, mechanical and physical properties of the CSCNT. [Copyright &y& Elsevier]

Transparent alumina film and fiber were prepared from the inorganic/organic polymer composites as a precursor by heating at 600–1000 °C in air. The composites were composed of basic aluminum chloride (BAC) and methyl cellulose (MC). The composite films were prepared by a casting method of aqueous solution of BAC and MC. An alumina film (40 μm thick) was obtained by heating at 1000 °C for 2 h, which exhibited high transmittance of above 85% in the range of 300–1000 nm. The phase of alumina changed from amorphous to γ-form between 800 and 900 °C. Upon heating at 1150 °C, the alumina transformed to α-form, and the appearance of the alumina film changed to opaque. Colored transparent alumina films were found to be prepared easily from the composite by the introduction of transition metal ions such as Au3+ and Co2+. Transparent and continuous alumina fiber was also obtained by heating of the composite fibers made by wet solution spinning of aqueous solution of BAC and MC. [Copyright &y& Elsevier]

The influence of heating conditions on the structure of hollow carbon fibers (H-CFs) during their fabrication from solid poly(vinyl alcohol) (PVA) fibers is reported. The hollow structure of PVA-derived carbon was formed by selective iodination and subsequent stabilization of precursor PVA fiber close to the fiber surface followed by carbonization. The broadening of X-ray diffraction peaks due to disorder and the small size effects of the (002) plane were strongly reduced by increasing the heat treatment temperature (HTT) from 800 to 3000 °C, but the asymmetric shape of (10) and (110) reflections suggests turbostratic layer stacking. The increase of HTT to 3000 °C increased the degree of graphitization evident from the decrease of interplanar spacing from 0.360 to 0.338 nm and the intensity ratio of D to G bands in Raman spectra from 0.93 to 0.58. The crystallite size, orientation and electrical conductivity of the resultant H-CFs were also improved with higher HTT. Besides, the size of the hollow core was also influenced by the HTT and both wall thickness and carbon yield decreased with higher HTT. The core of the H-CFs could be easily filled with polymer by bulk polymerization of monomer. [ABSTRACT FROM AUTHOR]

PVA is reinforced with SWCNTs using green tea extract as a dispersant to achieve good dispersion of the SWCNTs in an organic solvent and finally high-performance composite fibers. A combination of green tea extract/DMSO/SWCNT/PVA is found to disperse larger aggregates of SWCNTs to individual or thin bundles of a few nanotubes. Incorporation of 0.5 wt% SWCNTs into PVA fibers yields a tensile strength of 2.42 GPa, a Young's modulus of 46 GPa, toughness of 105 J · g−1 at a failure strain of 11%, and a loop strength of 245 MPa, much higher than the values of commercial PVA fibers. The incorporation of highly dispersed SWCNTs suppresses the fibrillation tendency of the PVA fibers. The applied load is effectively transferred from the matrix to the SWCNTs. [ABSTRACT FROM AUTHOR]

Abstract: Silk fibers from Bombyx mori silkworm was degummed with different concentration of citric acid, and the physical properties and fine structure were investigated to elucidate the effects of citric acid treatment. The silk sericin removal percentage was almost 100% after degumming with 30% citric acid which resulted in a total weight loss of 25.4% in the silk fibers. The surface morphology of silk fiber degummed with citric acid was very smooth and fine, showed perfect degumming like traditional soap-alkali method. The tensile strength of silk fiber was increased after degumming with citric acid (507MPa), where as the traditional soap-alkali method causes to decrease the strength about half of the control silk fiber (250MPa). The molecular conformation estimated by Fourier transform infrared spectroscopy and the crystalline structure evaluated from X-ray diffraction curve stayed unchanged regardless of the degumming with citric acid and soap. The dye uptake percentage of silk fiber degummed with citric acid decreased slightly, about 4.2%. On the other hand, the dye uptake percentage of silk degummed with soap was higher which indicates the disordering of the molecular orientation of the laterally ordered structure, accompanied with the partial hydrolysis of silk fibroin molecules by the alkali action of soap. The thermal properties were greatly enhanced by soap and citric acid degumming agents. Dynamic mechanical thermal analysis showed silk degummed with citric acid is more stable in higher temperature than that of soap. With heating at above 300°C, the silk degummed with citric acid shows an increase in storage modulus and an onset of tan δ peaks at 325°C and the melt flow of the sample was inhibited. The degumming of silk fibers with citric acid is safe and the results obtained are quite promising as a basis for possible future industrial application. [Copyright &y& Elsevier]

Abstract: To study the spinning condition of natural biopolymer silk, the silk fibers were directly acquired from Bombyx mori silkworm, N140×C140 by a simple artificial forcibly silking method at the speed of 60, 120, 180 and 240cmmin−1, respectively and its microstructure and physical properties were evaluated. The fine silk fibers (about 8μm) were obtained at faster spinning speed, 240cmmin−1. The tensile properties of silk fibers were remarkably increased with raising the forcibly spinning speeds. The β-sheet structure contents of silk fibers obtained at higher speed were considerably increased. The fibers obtained by different spinning speeds exhibited a fairly similar X-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber diameter. The fine silk fibers obtained at higher speed (240cmmin−1) exhibited a slightly higher thermal stability, as shown by the upward shift of differential scanning calorimetry (DSC) decomposition temperature. [Copyright &y& Elsevier]

• Cellulosic non-woven fabrics were prepared from ionic liquid solutions. • Suitable molecular weights of cellulose contributed to forming ultrafine fibers. • Fiber diameter was reduced and strength was improved as air velocity increased. • Ultrafine cellulose fibers with a high strength of ca. 940 MPa were obtained. A wet-type solution blow spinning system equipped with a single concentric nozzle was assembled to investigate the key factors for preparing ultrafine regenerated cellulose fibers. The effects of the degree of polymerization (DP) of cellulose and the velocity of blown air on fiber morphology were studied by rheological analyses and scanning electron microscopy. The results demonstrated that cellulose with a DP of 2365, together with a high air velocity, could aid the formation of continuous ultrafine fibers. Fluid filament deformation was observed using a high-speed camera and clearly correlated with the final fiber morphology. Additionally, aligned ultrafine fibers were spun on a rotational collector and their mechanical properties and structural parameters were characterized. Ultrafine cellulose fibers with a high strength of 941.4 MPa and a high crystallite orientation of 0.909 were obtained. [ABSTRACT FROM AUTHOR]

• Novel wet type solution blow spinning using water mist/vapor coagulant. • Preparation of fine regenerated cellulose fibers from an ionic-liquid solution. • Fibers with an average diameter of ˜1 μm, high crystallinity, and high orientation. • Spinning conditions decisive for fiber structure and tensile properties. A wet type solution blow spinning system with a water-mist coagulation chamber was developed to spin fine regenerated cellulose fibers from the non-volatile ionic liquid solvent 1-ethyl-3-methylimidazolium diethyl phosphate. The molecular weight distribution of cellulose, and the rheological properties and spinnability of its spinning solution were evaluated. Scanning electron microscope observations indicated that the fine water mist/vapor was important for efficient coagulation of the stretched solution jets. Under optimized spinning parameters, a non-woven fabric was obtained consisting of fine fibers with an average diameter of 0.98 ± 0.62 μm. The tensile strength of the samples was greatly influenced by the fabric structure formed upon regeneration of cellulose from solution. X-ray diffraction and polarized optical microscopy measurements revealed that the prepared cellulosic non-woven fabric was highly crystalline and had a well-defined molecular orientation, respectively, which might have contributed to the increased tensile strength. [ABSTRACT FROM AUTHOR]

Herein, we report an efficient and environmentally-friendly approach for the preparation of silver nanoparticle-coated silk fibers (SFs) through self-assembly of hyperbranched poly(amine-ester)s modified silver nanoparticles (HBPAE/AgNPs) on hyperbranched poly(amidoamine)s modified silk fibers (HBPAA/SFs) driven through intermolecular interactions between hydroxyl-terminated HBPAE and amino-terminated HBPAA. The HBPAE/AgNPs had a particle size of 11.8 nm and were slightly negatively charged. The self-assembly process was conducted by successively impregnating the SFs with HBPAA and HBPAE/AgNPs solutions. Up to 160 mg/L of HBPAE/AgNPs could completely self-assemble onto HBPAA/SFs (2 g) at room temperature within 10 min, allowing the Ag content of HBPAE/AgNP-coated HBPAA/SFs to be precisely controlled up to 8 mg/g by simply adjusting the concentration of the AgNPs. The antibacterial activity of HBPAE/AgNP-coated HBPAA/SFs was dose-dependent and the minimum Ag content was determined as 1.5 mg/g with an inhibitory rate of over 99%. Further characterization demonstrated that the as-prepared HBPAE/AgNP-coated HBPAA/SFs have unique structural features including well-dispersed NPs on the surface and good chemical stability. The developed self-assembly technology may provide a simple, efficient, and environmentally-friendly coating strategy for the precise control of Ag content on coated fibers, which is important for the quality control of antibacterial textiles. [ABSTRACT FROM AUTHOR]

We propose a copper iodide (CuI)-doped nylon mesh prepared using polyiodide ions as a precursor toward anti-biofouling polymer textile. The CuI-doped nylon mesh was subjected to the prevention of biofouling in marine environments. The attachment of the marine organisms was markedly inhibited on the CuI-doped nylon mesh surface until 249 days. Scanning electron microscopy-energy dispersive X-ray analysis indicated that copper compounds were maintained in the nylon mesh after the field experiment, although copper content in the nylon mesh was reduced. Therefore, the copper ions slowly dissolved from nylon mesh will contribute to the long-term prevention of biofouling. Furthermore, electron spin resonance analysis revealed the generation of reactive oxygen species (ROS) from CuI-doped nylon mesh after the field experiment. One of the possibilities for toxic action of copper ions will be the direct effect of Cu-induced ROS on biofilm forming on nylon mesh surface. The proposed polymer textile can be applied to fishing and aquafarming nets, mooring rope for ship, or silt fence to restrict polluted water in marine environments. [ABSTRACT FROM AUTHOR]

Abstract: Many textiles have been often used in marine environments for a wide variety of purposes. Consequently, effective and clean methods to prevent biofouling in these textiles are needed. In this study, a nylon mesh doped with AgI was examined for its antifouling performance. The nylon mesh was iodinated with an iodine–potassium iodide aqueous solution and subsequently immersed in silver nitrate solution to form AgI particles in the fiber. SEM-EDX analysis indicated that the AgI crystals were highly incorporated into the nylon 6,6 polymer (173wt% gain). The bactericidal activity of AgI-doped nylon mesh was more than 200 times higher than that of silver-coated nylon mesh. Furthermore, continuous prevention of biofouling in the coastal marine environment was attained for 437days by using the AgI-doped nylon mesh. Since the concentration of the released silver ions from the nylon mesh was estimated to be less than 1ppb, the proposed nylon mesh is useful as an effective and clean method for prevention of biofouling in polymer textiles. [Copyright &y& Elsevier]

Abstract: To utilize the extreme reinforcing performance of chitin whiskers (ChWs), the current work was undertaken to fabricate nanocomposites embedded with highly uniaxial oriented ChWs into the matrix polymer. Fibers of poly(vinyl alcohol) (PVA)/ChWs were prepared by gel spinning and the fibers were subjected to a hot drawing to their maximal draw ratio. WAXD analysis revealed the very high orientation of ChWs in the PVA matrix. DSC measurements showed that, upon ChWs loadings, crystallinity of PVA increased and non-isothermal cooling crystallization peak of PVA shifted towards lower temperature, indicating the interaction of PVA with ChWs. Measurement of infrared dichroism suggested that the orientation of overall PVA chains increased with the increase in ChWs loading due to the possible dragging of PVA chains attached with ChWs during drawing, which resulted higher PVA crystallinity in the composites. The stress transfer in PVA/ChWs interface quantified by X-ray diffraction evidenced the strong adherence between the two. The stress transfer between PVA and ChWs interface, and higher PVA crystallinity induced by ChWs were reflected to the outstanding enhancement in mechanical- and anti-creep properties of nanocomposite fibers. [Copyright &y& Elsevier]

Abstract: Hollow carbon fibers were fabricated from solid poly(vinyl alcohol) (PVA) fibers with the aid of an iodine pretreatment followed by stabilization. Iodination converted the chemical structure of PVA to polyene form due to dehydration reaction, and stabilization of heat treatment at 200°C in air provided insolubilization of iodinated PVA fibers. These processes extremely enhanced the carbon yield and enabled to obtain intact carbon fiber. By selective iodination and subsequent stabilization within the fiber cross-section close to the fiber surface, hollow carbon fibers were made through the carbonization. [Copyright &y& Elsevier]

Abstract: Structural development of isotactic polypropylene (iPP) fibers was analyzed in real time through in-situ WAXD/SAXS and fiber temperature measurements during CO2 laser-heated drawing because the CO2 laser irradiation can nearly fix the necking position on the running fiber. The in-situ WAXD/SAXS measurements were carried out with a high time-resolution of 0.4 ms. The as-spun iPP fibers of two different initial structures were laser-heat-drawn to a draw ratio of 6.5. For the drawing of PP fiber containing mesophase structure, diffraction from the oriented mesophase remained until an elapsed time of 1.0 ms, when oriented α-phase crystal started to form. Meanwhile, for the drawing of PP fiber containing both an α-phase and a mesophase structure, fragmented microcrystals were reorganized by orientation-induced crystallization before an elapsed time of 1.0 ms. The long period increased drastically with fragmentation, and decreased with reorganization. The long period was about 16 nm for both drawn fibers. [Copyright &y& Elsevier]

Abstract: High-strength composite fibers were prepared from polyvinyl alcohol (PVA) (Degree of polymerization: 1500) reinforced by single-walled carbon nanotubes (SWCNTs) containing few defects. The SWCNTs were dispersed in a 10wt.% PVA/dimethylsulfoxide solution using a mechanical homogenizer that reduced the size of SWCNT aggregations to smaller bundles. The macroscopically homogeneous dispersion was extruded into cold methanol to form fibers by gel spinning followed by a hot-drawing. The tensile strength of the well-oriented composite fibers with 0.3wt.% SWCNTs was 2.2GPa which is extremely high value among PVA composite fibers ever reported using a commercial grade PVA. The strength of neat PVA fibers prepared by the same procedure was 1.7GPa. Structural analysis showed that the PVA component in the composite fibers possessed almost the same structure as that of neat PVA fibers. Hence a small amount of SWCNTs straightforward enhanced by 0.5GPa the tensile strength of PVA fibers. The results of mechanical properties and Raman spectra for the SWCNT composites suggest the relatively good interfacial adhesion of the nanotubes and PVA that improves the load transfer from the polymer matrix to the reinforcing phase. [Copyright &y& Elsevier]

Abstract: Because rapid and uniform laser heating can fix the neck-drawing point in continuous drawing of PTT fiber, we have successfully analyzed the fiber structure development in the continuous drawing process by in-situ measurement with a time resolution of less than 1ms. In this study, we investigated fiber structure development for PTT around the neck point controlled with a CO2 laser-heated apparatus during continuous drawing, through on-line measurements of WAXD, SAXS, and fiber temperature. Fiber temperature attained by laser radiation initiated a rise around −3mm in relation to the neck point at 0mm, and increased to about 90°C, which is past the 45°C T g for PTT. The instantaneous increase in fiber temperature continued with a vertical ascent, with plastic deformation around the neck point. The crystalline diffraction pattern was revealed initially at the elapsed time of 0.415ms immediately after necking, and remained fairly constant with elapsed time. The ultimate crystalline diffraction pattern for a completely drawn fiber showed little difference from that at the initial stage. In PET a two-dimensionally ordered structure in the form of a mesophase was detected immediately after the necking, whereas in PTT the phenomenon was not observed. With elapsed time, the d spacing of (002) plane decreased gradually due to transformation of the initial all-trans conformation into trans-gauche-gauche-trans conformation, and ultimately the PTT molecular chain could favorably adopt the trans-gauche-gauche-trans conformation. SAXS pattern immediately after the necking revealed an X-shape; the scattering intensity concentrated on meridian directions due to individual crystal development, and at 2ms two-pointed scattering started to appear. Past 8ms, the typical two-pointed scattering pattern was prominent and its intensity increased with elapsed time. Long period decreased with increasing elapsed time, but the crystallite size of meridian (002) plane hardly changed. The decrease in long period might be caused by chain relaxation in the amorphous region. [Copyright &y& Elsevier]

Abstract: Rubber composite sheets filled with 5wt.% and 30wt.% of highly aligned carbon nanotubes (CNTs) were fabricated through conventional rubber technology. The alignment of CNTs was possibly derived from dragged shear force during the optimized milling process. The selective alignment of CNTs led to enhancements in the elastic modulus, thermal conductivity, electrical conductivity, and electromagnetic shielding property, compared to neat rubber sheet. [Copyright &y& Elsevier]

Abstract: Epoxy/vapor grown carbon nanofiber composites (VGCF) with different proportions of VGCF were fabricated by the in situ process. The VGCFs were well dispersed in both of the low and high viscosity epoxy matrices, although occasional small aggregates were observed in a high viscosity epoxy of 20wt.%. The dynamic mechanical behavior of the nanocomposite sheets was studied. The storage modulus and the glass transition temperature (T g) of the polymer were increased by the incorporation of VGCFs. The electrical and mechanical properties of the epoxy–VGCFs nanocomposite sheets with different weight percentages of VGCFs were discussed. The results were that both had maximum tensile strength and Young’s modulus at 5wt.% for both materials and reduced the fracture strain with increasing filler content. The electrical resistivity was decreased with the addition of filler content. Mechanical, electrical and thermal properties of low viscosity epoxy composites were resulted better than that of the high viscosity composites. [Copyright &y& Elsevier]

Abstract: The structure development in the continuous laser-heated drawing process of poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) fiber was analyzed by in-situ X-ray diffraction measurement. Because of the rapid and uniform laser heating, and the resultant steady-state nature of the necking-drawing, the structure development after the on-set of necking could be measured in the time resolution of several hundred microseconds. We found for the first time the temporal appearance of meridional (001′) diffraction at several milliseconds after the on-set of necking indicating that the mesophase structure similar to the one reported for poly(ethylene terephthalate) was also formed in the initial stage of fiber structure development of PEN. The d-spacing of the (001′) diffraction 1.230±0.003nm was shorter than the c-axis lengths of both α and β crystals. [Copyright &y& Elsevier]