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.     

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.     

Solution blow spun titania nanofibers from solutions of high inorganic/organic precursor ratio

In this work titania nanofibers were produced from different precursor solutions by solution blow spinning. Hydrophilic polyvinylpyrrolidone, hydrophobic poly(vinyl acetate) and amorphous and semi-crystalline poly(lactic acid) polymers were used with green-solvents and titanium isopropoxide as the inorganic precursor. Hybrid nanofibers with high inorganic loading content were successfully produced from all precursor solutions. The fibers were calcined at different annealing temperatures for evaluation of phase transitions. The minimum temperature to obtain pure titania fiber was found to be 500 °C, as assessed by thermal characterization. Anatase was the unique polymorph formed at this annealing temperature. This is of paramount importance due to its photocatalytic character. Calcination at high temperatures showed that rutile slightly appeared at 600 °C for the polyvinylpyrrolidone-based system and showed a strong peak at 700 °C for all systems, co-existing with anatase as minor phase. The use of amorphous and semicrystalline poly(lactic acid) polymers did not influence the anatase crystal size and phase conversion. This was found to be dependent on the annealing temperature and medium acidity, as currently found in powder synthesis.     

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.     

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.     

Ni/NiO-carbon composite fibers prepared by solution blow spinning: Structure and magnetic properties

Nickel/nickel oxide-carbon magnetic fibers were prepared by Solution Blow Spinning (SBS) of polyvinyl alcohol (PVA) and Ni-nitrate. As-spun fibers with relative Ni nitrate/PVA concentrations of 30 wt% and 60 wt% were calcined at 550 °C in argon flux. The samples characterization was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and DC magnetic measurements. TEM images show a carbon matrix containing sphere-like nanoparticles with diameters in the range of 4–45 nm. The magnetic assessment shows the presence of superparamagnetic small particles with blocking temperatures between 14 and 22 K, and large particles that are thermally blocked at 300 K. The low magnetization signal, with saturation magnetization in the range of 7–10 emu/g, is due to dead magnetic layers at the surface of nanoparticles.     

Phase behavior and mechanism of formation of protofiber morphology of solution spun poly(acrylonitrile) copolymers in DMF‐water system

Phase diagrams of a series of copolymers of acrylonitrile (AN) and acrylic acid (AAc) were constructed using linearized cloud point correlation. The miscibility region in the phase diagram was found to increase with the increase in AAc content of the copolymers. For various compositions, χ₁₃ (polymer–water interaction parameter) values were estimated by sorption experiment. As the hydrophilic nature of the polymer increased with the increase in the content of acrylic acid, the χ₁₃ interaction parameter was found to decrease from poly(acrylonitrile) homopolymer to its copolymer with 50 mol % acrylic acid (AA50B). The polymer–solvent interaction parameters (χ₂₃) and composition at the critical points for all the polymers were determined by fitting the theoretical bimodal curves to the experimental cloud point curves using Kenji Kamide equations. The polymer composition at the critical point was found to increase by 400% with increasing AAc content. The polymers were solution spun in DMF‐water coagulation bath at 30°C and their protofiber structures were investigated under scanning electron microscopy. The observed morphological differences in protofibers were explained on the changes brought about in the phase separation behavior of the polymer–solvent–nonsolvent systems. The copolymers with higher acrylic acid content could be solution spun into void free homogeneous fibers even at conditions that produced void‐filled inhomogeneous fibers in poly(acrylonitrile) and its copolymers with lower AAc content. The experiments demonstrate the important role of thermodynamics in deciding the protofiber morphology during coagulation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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     

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.     

Morphology of ultrafine polysulfone fibers prepared by electrospinning

Ultrafine fibers of bisphenol‐A polysulfone (PSF) were prepared by electrospinning of PSF solutions in mixtures of N,N‐dimethylacetamide (DMAC) and acetone at high voltages. The morphology of the electrospun PSF fibers was investigated by scanning electron microscopy. Results showed that the concentration of polymer solutions and the acetone amount in the mixed solvents influenced the morphology and the diameter of the electrospun fibers. The processing parameters, including the applied voltage, the flow rate, and the distance between capillary and collection screen, were also important for control of the morphology of electrospun PSF fibers. It was suggested that uniform ultrafine PSF fibers with diameter of 300–400 nm could be obtained by electrospinning of a 20 % (wt/v) PSF/DMAC/acetone (DMAC:acetone = 9:1) solution at 10–20 kV voltages when the flow rate was 0.66 ml h^?1 and capillary–screen distance was 10 cm. Copyright © 2004 Society of Chemical Industry     

Macromolecular modification of EPDM: Wettability,miscibility, and morphology study

The present investigation deals with studies on wettability, miscibility, and morphology of the macromolecularly modified EPDM. Two different maleated EPDM rubbers (grafted rubber) were chosen (0.5 and 1% maleation) for such modification and they were used in various proportions. Wettability of the rubber substrate, as observed from dynamic contact angle measurement, was improved using these grafted rubbers. Results of X‐ray photoelectron spectroscopy showed an increase in oxygen level with higher levels of grafted rubber in the blends. Morphology study by transmission electron microscopy showed a smaller domain size for the blend with higher maleic anhydride content in the grafted rubber. The viscosity versus blend ratio results showed a negative deviation behavior for blends with 1% grafted rubber, whereas a positive negative deviation behavior was observed in blends with 0.5% grafted EPDM. As the strength of interaction increased, the glass transition shifted to a higher temperature. All blends were heterogeneous, as indicated by different degrees of dispersion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2647–2661, 2001     

Effects of molecular weight of polysulfone on phase separation behavior for cyanate ester/polysulfone blends

The effects of molecular weight of polysulfone (PSF) on the morphology of bisphenol‐A dicyanate (BADCy)/PSF blends were studied. Because the viscosity of the blend increased and the miscibility between BADCy and PSF decreased with the increase of PSF molecular weight, these two competing effects on the phase‐separation were investigated. It was observed that the effect of viscosity was predominant: the viscosity of the blends at the onset point of phase separation increased with the increase of PSF molecular weight. The phase separation mechanism depends on the viscosity of the blends at the onset point of phase separation and determines the morphology of the blends. Because the increasing viscosity with increasing the molecular weight of PSF suppressed the nucleation and growth even with 10 phr of PSF content, phase separation occurred through spinodal decomposition to form the combined morphology having both PSF particle structure and BADCy particle structure. The combined morphology and the BADCy particle structure were obtained with a smaller amount of high molecular weight PSF content. This indicates that the viscosity of the blends at the onset point of phase separation is the critical parameter that determines the morphology of the blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 921–927, 2000     

Optimization of electro-blown polysulfone nanofiber mats for air filtration applications

Durable, robust, and hydrophobic air filtration media was produced via electro-blow spinning (EBS) technique using polysulfone (PSU) due to its superior properties. To our knowledge, this is the first optimization study of PSU nanofiber production via EBS technique for air filtration applications. Concentration, air pressure, and voltage were determined as independent variables for the optimization based on “smaller is the better” approach of Taguchi Design of Experiment. The optimized values which supplied the smallest average fiber diameter (AFD) possible were obtained as 13 wt% PSU, 3 bar, and 7.5 kV. The AFD of the sample obtained from the confirmation experiment was calculated as 105 ± 34 nm. Surface morphologies, porosity values, and wettability behaviors of the samples were investigated by using scanning electron microscopy, gravimetric method, and water contact angle measurements, respectively. PSU nanofiber mats exhibited superhydrophobic behavior (water contact angle values up to 159.8°) which is important for various separation processes. Samples prepared at different deposition times (15, 30, 45, and 60 min) were investigated in terms of particle capture efficiency and pressure drop. The 0.3 μm particle filtration efficiency was found to be 98.09% at an expense of 202 Pa pressure drop which would be suitable for various respiratory and HVAC filter applications.     

熔体直纺环吹细旦FDY生产工艺探讨

对熔体直纺环吹83 dtex/72 f的细旦FDY生产中的工艺进行了较系统的探讨,结果表明:通过选择合适的PET端羧基值、控制熔体在管道中的降解和环吹的工艺条件,可纺性良好,并可以生产出指标良好的涤纶细旦FDY。     

FDY油剂的润湿性及其对纺丝加工性能的影响

介绍了 FDY油剂润湿性的意义及其在纺丝加工过程中的作用。讨论了润湿性对加工纤维的摩擦系数、抗静电性、强伸度的均匀性及可纺性的影响程度     

Phase separation behavior of cyanate ester resin/polysulfone blends

The composition of the blends and the curing temperature affect the morphology of the blends and the phase separation mechanism. The phase separation mechanism depends on the viscosity of medium at the initial stage of phase separation determined by the amount of thermoplastics and the curing temperature, and is closely related with the final morphology. When the homogeneous bisphenol A dicyanate (BADCy)/polysulfone (PSF) blends with low content of PSF (less than 10 wt %) were cured isothermally, the blends were phase separated by nucleation and growth (NG) mechanism to form the PSF particle structure. On the other hand, with more than 20 wt % of PSF content, the BADCy/PSF blends were phase separated by spinodal decomposition (SD) to form the BADCy particle structure. With about 15 wt % of PSF content, the blends were phase separated by SD and then NG to form a combined structure having both the PSF particle structure and the BADCy particle structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 33–45, 1999     

Fabrication of polysulfone asymmetric hollow‐fiber membranes by coextrusion through a triple‐orifice spinneret

Polysulfone (PSf) asymmetric hollow‐fiber membranes, which have a dense outer layer but a loose inner layer, were tentatively fabricated by coextrusion through a triple‐orifice spinneret and a dry/wet‐phase inversion process. Two simple polymer dopes were tailored, respectively, for the dense outer layer and the porous inner layer according to the principles of the phase‐inversion process. By adjusting the ratio of the inner/outer extrusion rate, the hollow‐fiber membranes with various thicknesses of outer layers were achieved. The morphology of the hollow‐fiber membranes was exhibited and the processing conditions and the water permeability of the membrane were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 259–266, 2004     

Formation of melt and solution spun polycaprolactone fibers by centrifugal spinning

Nano‐ and microfibers have a myriad of applications ranging from filtration, composites, energy harvesting, to tissue engineering and drug delivery. Electrospinning, the most common method to produce such fibers, has many limitations including low fiber output and solvent dependency. Centrifugal spinning is a new technique that uses centrifugal forces to form nano‐ and microfibers both from solution and the melt. In this work, the effect of melt temperature, collector distance, rotation speed, and concentration (for polymer solutions) of polycaprolactone were evaluated with respect to fiber morphology, diameter, alignment, and crystallinity. The fiber diameter generally decreased with increasing rotation speed and reduced concentration. Crystallinity for spun fibers decreased compared to the bulk polymer. Fiber alignment was improved with rotation speed for the melt‐spun fibers. The fiber mats were evaluated as tissue scaffolds with neuronal PC12 cells. The cells adhered and extended neurites along the fibers for both melt and solution‐spun scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41269.