Fabrication and UV-blocking property of nano-ZnO assembled cotton fibers via a two-step hydrothermal method

A novel ZnO/cotton composite, in which ZnO nanoparticles were synthesized directly inside of the lumen and the mesopores of cotton fibers, was fabricated via a simply two-step hydrothermal method in situ using zinc nitrate hexahydrate and hexamethylenetetramine as raw materials. The as-obtained cotton sample was characterized by powder X-ray diffractometer, field emission scanning electron microscopy, and energy-dispersive spectroscopy, respectively. The UV-blocking property of the as-obtained sample was investigated by UV–vis spectrophotometry. The results showed that hexagonal wurtzite nano-ZnO with a diameter of about 30–40 nm was successfully assembled into the lumen as well as the mesoporous structure of the cotton fibers. The UV-blocking property of the modified cotton fibers can be greatly improved by assembling nano-ZnO into the inner of cotton fibers. Comparing with the neat cotton fibers, the UV-blocking ratio of the ZnO assembled cotton fibers inside of KBr disk could reach 80% at 300 nm and 95% at 225 nm, respectively. Therefore, it demonstrated a significant advance in protective functional treatment and provided a potential commercialization.     

Synthesis and characterization of polyvinyl butyral–Al(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> composite sol used for alumina based fibers

The polyvinyl butyral–Al(NO₃)₃ composite sol used for alumina based fibers was synthesized by the sol–gel process in an aqueous solution using the polyvinyl butyral (PVB) and Al(NO₃)₃ · 9H₂O (AN). The alumina fibers with smooth surface and uniform diameter were prepared. PVB, AN, PVB–AN composite sol and alumina fibers have been studied by X-ray diffraction (XRD), derivative thermo-gravimetric/differential scanning calorimetry (DTG/DSC), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The interaction between PVB and AN was reported. The presence of a new weak peak at low angle and deviation of diffraction angle in XRD patterns implied that the reaction between PVB and AN took place. DTG/DSC curves showed the decomposition temperatures of AN increased and that of PVB decreased in the PVB–AN composite sol, which was considered to be caused by the interaction between PVB and AN. FTIR spectroscopy of PVB–AN gel showed a new absorption peak due to the COOH group, which implied the presence of new reaction product. The schematic reaction formula was shown in this paper. The XRD pattern of fibers sintered at 1,200 °C showed the formation of α-alumina and the fibers showed smooth surface and uniform diameter.     

Preparation and characterization of zirconium titanate fibers with good high temperature performance

Zirconium titanate (ZT) precursor fibers were prepared via sol–gel technique by dry-spinning method using polyacetylacetonatozirconium (PAZ) and tetrabutyl titanate (TBOT) as starting materials. PAZ and TBOT were added into methanol with vigorous stirring at room temperature for 2 h and mixed together homogenously. The mixture came into being a new and complicated polymerization system, and PAZ and TBOT were connected through –O– bridge forming the –O–Zr–O–Ti–O– linear chains. The evolutions from the precursor fibers to polycrystalline oxide fibers were characterized by Fourier transform infrared (FT–IR) and thermal gravimetry/differential thermal analysis (TG/DTA). The surface of the ZT fibers was smooth, dense in cross-section without cracks by scanning electronic spectroscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The size of the nanocrystals was less than 50 nm and arranged compactly by atomic force microscopy (AFM). The fibriform was still kept and the size of the grains was up to 400–500 nm due to the grain growth with increasing temperature and the ZT fibers were with good high temperature performance.     

Preparation and properties of barium-ferrite-containing glass ceramic fibers via an electrospinning/sol–gel process

Barium-ferrite-containing glass ceramic fibers were successfully prepared by the combination of a sol–gel process and electrospinning technique using basic iron formate, barium acetate and boric acid as the starting materials. After leaching of barium borate matrix, pure phase BaFe₁₂O₁₉ fibers were obtained. The relationship of aged time and viscosity of the precursor solution was studied and the results showed that the viscosity corresponding to the spinnable state was 1–4 Pa s. The morphology, structure and magnetic properties of the obtained fibers were characterized with scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis–differential scanning calorimetry, vibrating sample magnetometer. The X-ray diffraction results indicate that only the M-type Ba-ferrite and Ba-borate exist. The fibers had rough surface and hollow structure with the diameter no more than 1 μm. The fibers were composed of 40 nm BaFe₁₂O₁₉ nanoparticles embedded in the borate matrix. The coercivity and saturation magnetization of the synthesized fibers were 4,106.9 Oe and 17.8 emu/g, respectively.     

Thermodynamic and experimental study of the interaction of silicon and carbon monoxide: Synthesis of silicon carbide nanofibers

The reaction of crystalline silicon with carbon monoxide to produce silicon carbide was studied. Thermodynamic simulation of the equilibrium phase composition of the nSi-mCO system was carried out in the range 300–2000 K (27–1727°C). Conditions required for silicon carbide was carried out applying various experimental modes (n, m, and T) and possible pathways of the reactions were determined. Interaction between crystalline silicon and carbon monoxide formation in a temperature range of 1000–1450°C. The order of the reaction in CO was found to be close to unity. Silicon carbide nanofibers with thicknesses of from 5 to 100 nm were synthesized and characterized by powder X-ray diffraction, mass-spectral elemental analysis, and scanning electron microscopy. A possibility of synthesizing high-purity silicon carbide fibers were experimentally evaluated.     

Sol–gel derived mesoporous bioactive glass fibers as tissue-engineering scaffolds

Mesoporous bioactive glass (MBG) fibers have been synthesized using the combination of a sol–gel process and a high velocity spray procedure by carefully controlling the sol composition, acidity and water content. A three-dimensional (3D) macro-structure with ∼50–100 μm interconnected macropores is formed in the spraying process. The MBG fibers possess well-ordered hexagonal mesostructure and excellent in vitro bioactivities. Sprague–Dawley (SD) rat osteoblasts have been cultured on MBG fibers. It is found that the MBG fibers have good cell biocompatibility and the 3D macro-structure is beneficial for cell attachment. It is anticipated that MBG fibers with controlled mesostructure and excellent in vitro bioactivity are good candidates for future tissue-engineering scaffolds.     

Synthesis and characterization of zinc titanate fibers by sol-electrospinning method

A facile and economic electrospinning approach has been developed for the synthesis of zinc titanate-rutile composite fibers as a nanofibrous mat at the first time. The composite fibers with different morphologies were obtained by calcination of the PVP/Ti(OC₄H₉)₄–Zn(CH₃COO)₂ fibers. The reaction mechanism was characterized by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infraction spectroscopy (FT-IR) spectra techniques. According to the thermal analysis, the phase of ZnTiO₃ occurred at 450 °C and it decomposed at 885 °C. FE-SEM micrographs indicated that the as-spun fibers were round and had a rather uniform and smooth surface with the diameters in the range of 300–800 nm over its length. Its morphology is greatly affected by the calcination temperatures.     

Synthesis of CaSnO<Subscript>3</Subscript> nanofibers by electrospinning combined with sol–gel

Calcium stannate (CaSnO₃) nanofibers were synthesized by electrospinning technique combined with a sol–gel process. The structure and morphology of the as-prepared CaSnO₃ nanofibers were characterized by X-ray diffraction and scanning electron microscopy, respectively. The samples had a band gap of about 3.87 eV, which was estimated by UV–Vis diffuse reflectance spectroscopy. On the basis of the experiment results, the composite fibers containing polymer and inorganic salt can be changed to pure CaSnO₃ nanofibers only when they were sintered at an appropriate temperature. At the same time, a possible mechanism of the nanofibers forming process was also proposed.     

Thermal analysis and spectroscopic studies of electrospun nano-scale composite fibers

The aim of this article is to develop nano-scale composite fibers from wood pulp, modified wood pulp, and polyethylene oxide (PEO). Composite fibers were developed in the diameter range of 339–612 nm. Alignment process of the composite fibers was done by electrostatic interactions between two collector disks. DSC results demonstrated a lower melting temperature of composite fibers than PEO powder. The development of crystalline structure in the composite fibers and acetylated wood pulp was poor. Thermogravimetric analysis revealed that the thermal stability of composite fibers were relatively lower than PEO powder. Fourier transform infrared spectroscopy (FTIR) showed significant differences between modified and unmodified wood pulp in the region of 960–1746 cm⁻¹. The peak intensity of acetylated wood pulp was appeared at 1746 cm⁻¹ because of acetyl groups. The composite fibers demonstrated the characteristic peak of PEO since less wood pulp was incorporated in the composite system.     

Structure and mechanical performance of in situ synthesized hydroxyapatite/polyetheretherketone nanocomposite materials

Nano-hydroxyapatite (HA) particles were prepared by a sol–gel method and polyetheretherketone (PEEK) composite materials containing a various amount of lab-prepared HA fillers had been successfully synthesized via an in situ synthesis process. The materials structure was characterized by infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy and the mechanical performance was investigated by a tensile strength test. The tensile strength of HA/PEEK composites reaches an optimal 108 MPa at 6.1% HA content. The composites with HA content below 17.4% exhibit a plastic break mode, while a brittle break mode above 17.4%. The results exhibit that the strong bonding between hydroxyapatite fillers and PEEK matrix has been achieved. And it was proved that this strong bonding may be mainly attributed to the physical factors, such as mechanical interlock between PEEK molecules and HA surface. The study clearly demonstrates that in situ synthesized HA/PEEK composite materials have the potential for use as an alternative material for hard tissue replacement.     

Synthesis and characterization of ambient temperature superionic solids in the composite system CuI–Ag<Subscript>2</Subscript>O–TeO<Subscript>2</Subscript>

The present work deals with the composite system (CuI) _x –(Ag₂O–TeO₂)_{100– x} , where x=30, 35, 40, 45, 50, 55, 60, 65, 70 and 75 mol%, respectively, synthesized by a solid-state reaction route. Powder specimens were analysed using differential scanning calorimetry, X-ray diffraction and Fourier transform infrared techniques. These studies have revealed the formation of Cu₃TeO₆, AgI and/or other phases. The ambient temperature electrical conductivities obtained for the samples using a complex impedance method were found to lie in the range 10^–6–10^–4 Scm^–1, with low activation energies, thus indicating their superionic nature. The typical composition 35CuI–32.5Ag₂O–32.5TeO₂ was identified as the best conducting one, having an electrical conductivity of 6×10^–4 Scm^–1 at 296 K and an activation energy of 0.23 eV. Ion transport number measurements carried out using Wagner's polarization technique as well as by an electromotive force method suggested that silver ions were responsible for the observed transport features of the composite system. Electronic Publication     

Disordered carbon nanofibers/LiCoPO<Subscript>4</Subscript> composites as cathode materials for lithium ion batteries

LiCoPO₄-coated disordered carbon nanofibers (CNFs/LiCoPO₄) were obtained by a sol–gel method, using triethyl phosphite or triethyl phosphate as the phosphorous source. The crystal structure of the products was analyzed by X-ray powder diffraction, while morphology was studied using scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. Optimal synthesis conditions for the CNFs/LiCoPO₄ in light of the best electrochemical performance are discussed. The best discharge capacity 105 mAh/g (or ca. 63% of the theoretical capacity) shows the material with 40% CNFs/LiCoPO₄ and addition coating by carbon black. This composition has a best purity of active materials and point coverage of CNFs. The X-ray photoelectron C1s spectra of the CNFs surface without and with sputter erosion show enhancement of C–O bonds at the fiber surface, which does not influence significantly electrochemical behavior of the composite materials.     

Phase transitions and ion transport in NASICON materials of composition Li1 + xZr2 ? xInx(PO4)3(x = 0–1)

NASICON materials of composition Li_{1 + x} Zr_{2 − x} In _x (PO₄)₃(x = 0–1) were synthesized. The phase constitution, particle size, and conductivity of these materials were studied as s function of synthesis temperature. High-temperature X-ray powder diffraction was used to study phase transitions in the materials synthesized. Low levels (x ≤ 0.1) partial substitution of indium for zirconium considerably increase the lithium ion conductivity and reduce the activation energy for conduction compared to the parent compound.     

Synthesis and optical property of NaTaO<Subscript>3</Subscript> nanofibers prepared by electrospinning

This paper describes a procedure of preparing sodium tantalite nanofibers for the first time. Sodium tantalite nanofibers were synthesised by electrospinning a sol–gel precursor solution of poly(vinyl pyrrolidone)/sodium tantalite, followed by careful sintering of the as-electrospun composite fibers at 550 °C for 3 h. The morphology, microstructure and crystal phase were investigated by transmission electron microcopy and X-ray diffraction. The optical property was characterized by ultraviolet–visible (UV–vis) spectrometer. Typical nanofibers were with diameter between 70 and 90 nm and length exceeding 0.1 mm. An unusual phenomenon, the red-shift of optical absorption band edge happened, indicated the fabricated NaTaO₃ nanofibers were potential good candidates for photocatalytic application. The experiment photodegradation of methylene blue by NaTaO₃ nanofibers under UV light irradiation was performed.     

Aligned electrospun cellulose fibers reinforced epoxy resin composite films with high visible light transmittance

Uniaxially oriented cellulose nanofibers were fabricated by electrospinning on a rotating cylinder collector. The fiber angular standard deviation (a parameter of fiber orientation) of the mats was varied from 65.6 to 26.2^o by adjusting the rotational speed of the collector. Optically transparent epoxy resin composite films reinforced with the electrospun cellulose nanofibrous mats were then prepared by the solution impregnation method. The fiber content in the composite films was in the range of 5–30 wt%. Scanning electron microscopy studies showed that epoxy resin infiltrated and completely filled the pores in the mats. Indistinct epoxy/fiber interfaces, epoxy beads adhering on the fiber surfaces, and torn fiber remnants were found on the fractured composite film surfaces, indicating that the epoxy resin and cellulose fibers formed good interfacial adherence through hydrogen-bonding interaction. In the visible light range, the light transmittance was 88–92% for composite films with fiber loadings of 16–32 wt%. Compared to the composite films reinforced with 20 wt% randomly oriented fibers, the mechanical strength and Young’s modulus of the composite films reinforced with same amount of aligned fibers increased by 71 and 61%, respectively. Dynamical mechanical analysis showed that the storage moduli of the composite films were greatly reinforced in the temperature above the glass transition temperature of the epoxy resin matrix.     

Fabrication and characterization of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles and polyurethane/(TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>) nanocomposite films

TiO₂–SiO₂ composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO₂–SiO₂ composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO₂–SiO₂) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO₂–SiO₂ composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO₂–SiO₂ composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO₂–SiO₂ core surface via surface functionalized reaction. The particle size of TiO₂–SiO₂ composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid films. The average particle size of the TiO₂–SiO₂ composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO₂–SiO₂ composite nanoparticles are well dispersed in the PU matrix.     

Structure and magnetic properties of the nanocomposites γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>

The structural features and magnetic properties of composite materials Fe₂O₃-SiO₂ consisting of γ-Fe₂O₃ nanoparticles in an amorphous porous matrix of SiO₂ were considered. The studied samples were synthesized by the sol-gel method. The structure of γ-Fe₂O₃-SiO₂ depending on the heating temperature was studied by electron microscopy, X-ray diffraction analysis, ESR and IR spectroscopy. Magnetic measurements were performed on a SQUID magnetometer in the range 2–350 K.     

Preparation, thermal, spectral and microscopic studies of calcium silicate hydrate–poly(acrylic acid) nanocomposite materials

A series of calcium silicate hydrate (C–S–H)-polymer nanocomposite (C–S–HPN) materials were prepared by incorporating poly(acrylic acid) (PAA) into the inorganic layers of C–S–H during precipitation of quasicrystalline C–S–H from aqueous solution. The as-synthesized C–S–HPN materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The XRD analysis of C–S–HPN materials suggest the intermediate organizations presenting intercalation of PAA within C–S–H and exfoliation of C–S–H. The SEM micrographs of C–S–H, PAA and C–S–HPN materials with different PAA contents exhibit the significant differences in their morphologies. The effect of the material’s composition on the thermal stability of a series of C–S–HPN materials along with PAA and C–S–H were studied by TG, DTA and DSC. Three significant decomposition temperature ranges were observed on the TG curves of all C–S–HPN materials.     

Evaluation of AMP–PAN composite for adsorption of Cs+ ions from aqueous solution using batch and fixed bed operations

Ammonium molybdophosphate–polyacrylonitrile (AMP–PAN) as an organic–inorganic composite ion exchanger was synthesized and investigated for adsorption of cesium from aqueous solutions. The synthesized composite was characterized by various techniques including X-ray powder diffraction, Fourier Transform Infrared Spectroscopy, thermogravimetry-differential scanning calorimetry, specific surface analysis, scanning election microscopy, X-ray fluorescence spectroscopy and CHN elemental analysis. The cesium adsorption on composite adsorbent was studied as a function of contact time, pH, temperature, and presence of various cations. In addition, adsorption thermodynamic parameters were determined and it was observed that the adsorption of cesium on the adsorbent is an endothermic and spontaneous process. The Langmuir and Freundlich adsorption isotherms were fitted to the adsorption data and the results showed that the Langmuir model best predicates the cesium adsorption on the adsorbent. The dynamic behavior of cesium adsorption on AMP–PAN ion exchanger was also investigated for a fixed bed column and desorption was carried out.     

Electrochemical performance of LiVPO<Subscript>4</Subscript>F/C composite cathode prepared through amorphous vanadium phosphorus oxide intermediate

LiVPO₄F/C composites with better electrochemical performance were prepared by calcination of LiF and amorphous vanadium phosphorus oxide (VPO) intermediate synthesized by a sol–gel method using H₃PO₄, V₂O₅ and citric acid as raw materials. The properties of LiVPO₄F/C composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests. The analysis of XRD patterns and Fourier transform infrared spectra (FTIR) reveal that VPO intermediate prepared by sol–gel method is amorphous and VPO₄ may exist in VPO intermediate. The compositions of LiVPO₄F/C composites are related to the calcination temperature for preparation of amorphous VPO/C intermediate and LiVPO₄F/C composite prepared by VPO/C synthesized at 700°C consists of a single crystal phase of LiVPO₄F. The electrochemical tests show that LiVPO₄F/C composite prepared by VPO/C synthesized at 700°C exhibits higher discharge capacity and excellent cycle performance. This LiVPO₄F/C composite displays discharge capacity of 133 mAh g⁻¹ at 0.5 C (78 mA g⁻¹) and remains capacity retention of 96.8% after 30 cycles, even at a high rate of 5 C, the composite exhibits high discharge capacity of 115 mAh g⁻¹ and capacity retention of 97% after 100 cycles.