Electrochemical assessment of novel misfit Ca-cobaltite-based composite SOFC cathodes synthesized by solution blow spinning

A new composite cathode for solid oxide fuel cells based on Ca₃Co₄O₉ (C349) and PrO_x was synthesized using a novel solution blow spinning (SBS) process. It is demonstrated that the presence of PrO_x in this cathode permits a remarkable decrease in total polarisation resistance, by ～15 times, mainly due to improvements in charge transfer and surface exchange processes.     

Effect of nitriding atmosphere on the morphology of AlN nanofibers from solution blow spinning

High purity AlN fiber is a promising thermal conductive material. In this work, AlN fibers were prepared using solution blow spinning followed by nitridation under N₂ or NH₃ atmosphere. Soluble polymer, such as polyaluminoxane, and allyl-functional novolac resin were adopted as raw materials to form homogeneous distribution of Al₂O₃ and C nanoparticles within the fibers, which could inhibit the growth of alumina crystal and promote their nitridation process. The effect of nitriding atmosphere on the fiber morphology was investigated. XRD results showed that complete nitridation was achieved at 1300 °C in the NH₃ or at 1500 °C in the N₂ atmosphere. Hollowed fiber structure was observed when fiber was nitrided in N₂ at high temperature, which was caused by gaseous Al gas diffusion, and this phenomenon was eliminated in NH₃ atmosphere. The nitridation mechanisms in different atmosphere were analyzed in detail. It was demonstrated that the nitridation of Al₂O₃ fibers in the NH₃ atmosphere offered the favored AlN morphology and chemical quality. Flexible AlN fiber with O content of 0.7 wt% was achieved after nitriding in NH₃ at 1400 °C. The high quality AlN can be used in thermal conductive composite materials.     

Effect of solution concentration in microfiltration properties of PLA mats produced by solution blow spinning

In order to remediate the difficulty of access to safe drinking water by 1/3 of the world population, mats produced by solution blow spinning (SBS) have a great potential for use in liquid filtration due to their small pores and high porosity, being capable of filtrating water by retaining particles and even microorganisms. In this context, this work aims the production and characterization of poly (lactic acid) mat obtained by SBS to be morphologically, thermally, and mechanically evaluated, as well as to observe water flux properties. The correlation between structure-processing-properties is an important part of the work, which shows that lower concentration of polymeric solution leads to mats with smaller average fiber diameter, greater crystallinity, impacting on their greater tensile strength. The water flux performance shows that mats obtained from higher polymer concentration solutions present less resistance to the water flow, which indicates larger pore diameters.     

Photocatalytic degradation of dyes and microorganism inactivation using solution blow spun silver-modified titania fibers

This work investigated the photocatalytic effect of silver-modified titania fibers on the degradation of rhodamine B (RB) and methylene blue (MB) and the inactivation of Escherichia coli and Staphylococcus aureus strains. Fibrous cotton-wool-like structures resulted from a combination of the sol-gel route to solution blow spinning followed by calcination of hybrids fibers at 700 °C. Analysis of X-ray diffraction and transmission electron microscopy confirmed the presence of anatase and rutile polymorphs and metallic silver on fibers. Silver-modified titania fibers inhibited bacterial growth in all experimental conditions regardless of the ion content or UV-irradiation. The effectiveness of microorganism inactivation of titania fibers increases upon UV-irradiation. pH did not influence the photodegradation of RB, and solutions with basic pH enhanced the removal of MB. In a fixed pH, MB presents a faster photodegradation rate as compared to RB, but they match when applying silver-modified titania fibers and UV-irradiation.     

Poly(lactic acid)/poly(vinyl pyrrolidone) membranes produced by solution blow spinning: Structure,thermal, spectroscopic,and microbial barrier properties

Submicrometric and nanometric poly(lactic acid)/poly(vinyl pyrrolidone) (PLA/PVP) fibrous membranes containing 0, 5, 10, 15, and 20 wt % PVP, with or without 20 wt % Copaiba oil (Copaifera sp.), were produced by solution blow spinning (SBS), using polymer injection rate of 120 μL min^?1, gas pressure of 2.4 kPa, working distance of 20 cm, and collector rotation of 200 rpm. The morphological, thermal, and spectroscopic properties of these membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry (TG), and Fourier transform infrared spectroscopy (FTIR). A method for the evaluation of membrane microbial barrier properties based on resazurin colorimetric method was proposed. Results showed that the addition of both PVP and Copaiba oil produced thicker fibers; otherwise, there was no effect on morphology. Thermal analyses (TG and DSC) indicated the immiscible nature of polymer blends produced, also confirmed by the spectroscopic studies. Antimicrobial barrier properties were related to the antimicrobial effect of Copaiba oil, combined with it hydrophobic nature. The hydrophilic nature of PVP favored degradation of fiber mats, impairing barrier property when higher concentrations of PVP were added. Results indicate that produced spun mats can potentially be used in applications such as wound dressing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44802.     

Hybrid hematite/calcium ferrite fibers by solution blow spinning: Microstructural,optical and magnetic characterization

Iron oxide and Ca-doped ferrite fibers were successfully prepared via Solution Blow Spinning (SBS). Fibers with several calcium contents (nFe/nCa = 3.0, 5.2, and 20.0 atomic ratio) were prepared after dissolving polyvinylpyrrolidone and Fe and Ca nitrates in an acidic aqueous solution, followed by SBS spinning and calcination at 800 °C. The morphological, structural, optical, vibrational, and magnetic properties of the fibers were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), Mössbauer spectroscopy, and magnetometry. The Rietveld refinement revealed Ca-doped fibers consisting of a mixture of Fe₂O₃, CaFe₂O₄, and Ca_3.6Fe_14.4O_25.2 crystalline phases. The Mössbauer spectra at 300 K showed a sextet belonging to the hematite phase and two doublets belonging to the calcium-related phases. Measurements at low temperatures showed a transition at 181.6 K attributed to Ca ferrite. The hematite fibers showed a saturation magnetization (Ms ~ 0.75 emu/g) relatively higher than the bulk α-Fe₂O₃ (Ms = 0.3 emu/g). The saturation magnetization increased from 3.6 to 6.4 emu/g with increasing Ca content.     

Stretchable and ultra-light non-woven thermal material with effective photo-thermal conversion based on solution blow spinning technology

An ideal insulation material has long been envisioned as one that not only minimizes heat loss but also provides additional heat. This study presents a non-woven fabric, comprising ultra-fine fibers embedded with zirconium carbide nanoparticles (ZrC NPs), prepared via solution blow spinning (SBS) and thermal crosslinking technology. Our results suggest that the fluffily-structured elastomer, fabricated using rigid polystyrene and flexible polyurethane, exhibits high porosity (96.96%), ultra-light characteristics (volume density of 47.12 mg cm⁻³), and effective heat retention (thermal conductivity of 23.1 mW mK⁻¹ at −40°C). Moreover, the fabric demonstrates remarkable fracture strength (206.38 kPa), high elongation at break (34.5%), and superior elasticity even after 100 compression cycles at 40% strain. Despite the fact that introducing 12% ZrC increases the thermal conductivity of the base fabric by 6%, the NPs endow the material with an excellent photothermal conversion function. Following 10 min of exposure to visible light, the surface temperature increases to 71.5°C. Given its impressive performance, this novel non-woven fabric demonstrates significant potential for applications in the field of cold protection.     

Solution blow spinning: A new method to produce micro‐ and nanofibers from polymer solutions

A solution blow spinning technique was developed using elements of both electrospinning and melt blowing technologies as an alternative method for making non‐woven webs of micro‐ and nanofibers with diameters comparable with those made by the electrospinning process with the advantage of having a fiber production rate (measured by the polymer injection rate) several times higher. The diameters of fibers produced ranged from 40 nm for poly(lactic acid) to several micrometers for poly(methyl methacrylate). This solution blow spinning method uses a syringe pump to deliver a polymer solution to an apparatus consisting of concentric nozzles whereby the polymer solution is pumped through the inner nozzle while a constant, high velocity gas flow is sustained through the outer nozzle. Analysis of the process showed that pressure difference and shearing at the gas/solution interface jettisoned multiple strands of polymer solution towards a collector. During flight, the solvent component of the strands rapidly evaporates forming a web of micro and nanofibers. The effect of injection rate, gas flow pressure, polymer concentration, working distance, and protrusion distance of the inner nozzle was investigated. Polymer type and concentration had a greater effect on fiber diameter than the other parameters tested. Injection rate, gas flow pressure, and working distance affected fiber production rate and/or fiber morphology. Fibers were easily formed into yarns of micro‐ and nanofibers or non‐woven films that could be applied directly onto biological tissue or collected in sheets on a rotating drum. Indeed, virtually any type of target could be used for fiber collection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Proteic sol-gel synthesis,structure and magnetic properties of Ni/NiO core-shell powders

Core-shell structured magnetic Ni/NiO powders were prepared by a proteic sol-gel route. Commercial gelatin and nickel nitrate were used as precursor materials. The synthesized material was calcined in air at 500 °C and further investigated by XRD, VSM and TEM. In order to investigate the effects of the structure on the magnetic properties, NiO powders were synthesized by three other methods for sake of comparison: citrate method, nitrate calcination and combustion method. XRD results revealed that the core-shell structured material is composed of 84.8 wt% NiO and 15.2 wt% Ni, while the samples from other methods are single phase. Hysteresis loop at room temperature showed a strong ferromagnetic behavior for samples prepared by proteic sol-gel and citrate methods. Powders from nitrate calcination and combustion showed weak ferromagnetic behavior most likely attributed to unpaired moments in their nanoparticles. The overall results showed that the proteic sol-gel method is a versatile chemical way to prepare Ni/NiO core-shell powders with high ferromagnetic signals.     

PCL/collagen blends prepared by solution blow spinning as potential materials for skin regeneration

Solution blow spinning (SBS), is used to prepare biocompatible fibrous materials based on poly-ε-caprolactone (PCL), modified with collagen. Materials with different compositions in terms of collagen are prepared. Structure, morphology, topography, wettability behavior, and cytotoxicity are studied in order to investigate the potentiality of these materials for medical applications in the field of tissue repairing and regeneration. Structure is studied by Fourier transformed infrared spectroscopy, morphology by scanning electron microscopy, topography by optical profilometry and wettability behavior by contact angle measurements. The addition of small amounts of collagen to PCL by SBS can induce important variations in the morphology and topography of the materials that, in turns, lead to changes in the wettability behavior and ability of HaCat cells adhesion and proliferation. The analysis of surface characteristics together with the use of a model based on mats constituted by cylinders disposed perpendicularly to each other point out that, under the compositions considered, the main factor leading to higher adhesion and proliferation of cells on the PCL/collagen is the presence of more available surface area.     

Ni/bentonite catalysts prepared by solution combustion method for CO2 methanation

A 20 wt% Ni/bentonite catalyst was prepared by a solution combustion synthesis (SCS), which exhibited higher activity for the CO₂ methanation than that of an impregnation method (IPM), and the catalyst prepared by SCS showed a CO₂ conversion of 85% and a CH₄ selectivity of 100% at 300℃, atmospheric pressure, and 3600 ml·(g cat)^-1·h^-1, and the catalyst exhibited stable within a 110-h reaction. The results showed higher metallic Ni dispersion, smaller Ni particle size, larger specific surface area and lower reduction temperature in the Ni/bentonite prepared by SCS than that of IPM. And the Ni/bentonite prepared by the SCS moderated the interaction between NiO and bentonite.     

纺丝溶液浓度对UHMWPE冻胶纤维萃取及拉伸性能的影响

通过冻胶纺丝法制备了纺丝溶液质量分数为8％～16％的超高相对分子质量聚乙烯(UHMWPE)冻胶纤维.研究了不同浓度冻胶纤维的相分离、萃取动力学、结晶性能、热性能和拉伸性能.结果表明:冻胶纤维成形之后的相分离过程开始60 min内较为剧烈,在约2000 min达到相分离平衡;冻胶纤维的萃取除油率随浴比的增大或萃取时间的延...     

Morphology and properties of Nafion membranes prepared by solution casting

In this study, dilute Nafion solutions consisting of solvents with various dielectric constants ? and solubility parameters δ, i.e. N,N′-dimethyl acetamide, N,N′-dimethyl formamide, N-methyl formamide, methanol-water mixture (4/1 g/g), ethanol-water mixture (4/1 g/g), and isopropanol-water mixture (4/1 g/g), were freeze dried and the conformations of Nafion molecules in dilute solutions were observed using transmission electron microscope. The membranes were prepared by solution casting from these solutions and evaporating the solvents at temperatures below T_G of Nafion, then annealing the membranes at 150 °C which was ∼50 °C above T_G of Nafion. We show Nafion molecular conformations in dilute solutions are strongly influenced by δ and ? of solvents. And, thus the morphology, water uptake, proton conductivity, and methanol permeability of membranes prepared by solution casting are also influenced by δ and ? of solvents.     

Nano/microfibers of EVA copolymer obtained by solution blow spinning: Processing,solution properties,and pheromone release application

Pheromones have been used for monitoring and control of insect pests in crops, reducing the use of pesticides. However, among obstacles for this technology to be more useful, is the control and time to release. In this way, this work aims the evaluation of the release of pheromones using micro/nanofibers of ethylene–vinyl acetate (EVA) produced by blow spinning. Solutions with 0.5–15 wt % EVA were prepared based on the solubility parameter of the copolymer. Fibers were obtained from solutions in the semidiluted concentration regime. Synthetic sex pheromones from the oriental fruit moth, Grapholita molesta and citrus leafminer Phyllocnistis citrella were incorporated into the micro/nanofibers. The morphology and structure of these fibers were evaluated employing field emission scanning electron microscopy and wide-angle X-ray diffraction. The fibers sizes (95–426 nm) were dependent on the feed rate of the solution. As a result, pheromone release has occurred linearly over 10 weeks, as determined by thermogravimetry analysis. The solubility parameter influences the amount incorporated in the fiber and the rate of pheromone release. The proposed fiber/pheromone system is interesting since it reduces the use of actives and can be used in several planting cycles and reused. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47647.     

Preparation,physical, and mechanical properties of soy protein isolate/guar gum composite films prepared by solution casting

Guar gum (GG) was incorporated into soy protein isolate (SPI) films using a blending solution casting method to form SPI/GG composite films. The effects of SPI and GG contents on the transparency, water susceptibility, mechanical, and gas‐barrier properties of SPI/GG composite films were analyzed. The results showed that SPI/GG composite films with added GG were much more tensile‐resistant, water‐resistant, gas‐barrier properties but less deformable property than SPI control film. The presence of GG also improved film barrier to the light. The analysis results of contact angle measurement, Fourier transform infrared spectroscopy, and scanning electron microscope indicated that GG induced increased network compactness of the composite films which resulted from strong intermolecular interactions, such as hydrogen bonding, that existed between SPI and GG. Findings indicate that GG may be used as a natural means to improve specific properties of SPI films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43382.     

Effect of fuel type on the microstructure and magnetic properties of solution combusted Fe3O4 powders

Porous magnetite (Fe₃O₄) powders were synthesized by solution combustion method using the glycine and urea at different fuel to oxidant ratios (ϕ). The combustion behavior depended on the fuel type as characterized by thermal analysis. The structure and phase evolution investigated by X-ray diffraction method showed nearly single phase Fe₃O₄ powders which were achieved only by using the glycine fuel at ϕ=1. The specific surface area and porous structures of the as-combusted Fe₃O₄ powders were characterized by N₂ adsorption-desorption isotherms and scanning electron microscopy, respectively. The surface area using the glycine fuel (62.6 m²/g) was higher than that of urea fuel (42.5 m²/g), due to different combustion reactions. Magnetic properties of the as-combusted powders were studied by vibration sample magnetometry which exhibited the highest saturation magnetization of 74 emu/g using the glycine fuel at ϕ=1 on account of its high purity and large crystallite size.     

The structures and properties of bio-based polyamide 56 fibers prepared by high-speed spinning

Bio-based polyamide 56 (PA56) fibers with the circular and trefoil cross-sections were prepared by high-speed spinning process. The pre-oriented yarns (POY) and draw-textured yarns (DTY) of PA56 were studied. The results showed that γ phase crystal dominated in POY with relative high degrees in the crystallinity and crystal orientation. In DTY, the drawing effect made the crystal transform from γ to α phase with the properties of the enhanced thickness of the crystal plate and the more order arranged molecules, that was the long period in these fibers was obviously increased to 7–8 nm. γ to α phase transition was much easy for PA56 fibers with circular cross-section during drawing. PA56 fibers had excellent moisture absorption and release performances. They were easy to be dyed and had a good color fastness.     

Synthesis,spinning, and properties of very high molecular weight poly(acrylonitrile-co-methyl acrylate) for high performance precursors for carbon fiber

In this paper, synthesis of very high molecular weight (VHMW) polyacrylonitrile-co-methyl acrylate (PAN-co-MA) polymers with weight average molecular weights of at least 1.7 million g/mole were repeatedly achieved on a laboratory scale using emulsion polymerization. The development of a hybrid dry-jet gel solution spinning technique for the VHMW PAN-co-MA enabled continuous spinning of 100 filament count tows, 100s of meters in length. Single filaments were analyzed and tested for tensile performance. Experimentally, the hybrid spinning method coupled with VHMW polymers produced precursor fibers with excellent tensile properties, averaging 954 MPa in strength and 15.9 GPa in elastic modulus (N = 296), with small filament diameters (5 μm). Results indicate a strong correlation between decreasing filament diameter, facilitated by high molecular weight polymer, and exponentially increasing tensile properties, using a hybrid dry-jet gel spinning process.     

Preparation and properties of polyamide 6 fibers prepared by the gel spinning method

Polyamide 6 (PA6) fibers were prepared by CaCl₂ complexation and the gel spinning technique. PA6 was partially complexed with CaCl₂ for the purpose of suppressing interchain amide group hydrogen bonding. The fibers were characterized with scanning electron microscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. In the gel spinning process, a mixed tetrachloroethane and chloroform solution was chosen as the coagulation bath after a comparison of different types of solutions. From our investigation of the morphology, structure, and mechanical properties of gel‐spun and hot‐drawn fibers, it was indicated that the modulus and tensile strength increased with increasing draw ratio, the orientation of the fibers was improved, and the cross section of the PA6 gel fibers became more smooth and tight. The results from the XRD, DSC, and FTIR tests indicated that calcium metal cations complexed with the carbonyl oxygen atoms of PA6. The maximum modulus and tensile strength values obtained in this study were 28.8 GPa and 413 MPa, respectively, at a draw ratio of 8. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structure evolution of ultra high molecular weight polyethylene/montmorillonite nanocomposite fibers prepared by melt spinning

Nanocomposite fibers of ultra high molecular weight polyethylene (UHMWPE) and organic montmorillonite (OMMT) were successfully prepared by a melt‐spinning process. The evolution of the microstructures of the nanocomposite fibers in the drawing process was preliminarily studied by X‐ray diffraction (XRD), differential scanning calorimetry, and small‐angle X‐ray scatters. With the increase of draw ratio values, the crystallinity of the nanocomposite fibers increased, the grain size decreased, and the folded chain crystals gradually transformed into extended chain crystals. The results suggested the evolution of the nanocomposite fibers was similar with that of the fibers made by gel‐spun drawing process. The addition of OMMT in UHMWPE improved the fluidity of the composites yet without affecting the crystal structure of UHMWPE in the drawing process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3930–3936, 2013