Fabrication of electrospun fibers from a waterborne soy-based polyurethane employing polyethylene oxide as a coformer

The fabrication of electrospun fibers made from aqueous dispersions of polyurethane obtained from renewable sources is an eco-friendly method to produce porous membranes for different applications. Polyethylene oxide (PEO) has been already employed in formulations for allowing fiber formation, but its role was not yet completely understood. In this work the fabrication of electrospun fibers made from biobased polyurethane aqueous dispersion with PEO in order to obtain regular fibers is performed. The role of PEO was studied by thermal analysis, infrared and Raman spectroscopy, rheology, and fiber morphology. Polyurethane fibers were obtained only when PEO was added, otherwise the dispersion is electrosprayed and particles are formed. It was observed that PEO modifies the rheology of dispersion and assists coalescence of polyurethane particles. On the other hand, polyurethane fibers conserved their diameter and their homogeneous structure after removal of PEO by immersion in water, which indicates that the distribution of both polymers was even within the fibers. This work provides both an insight on the role of PEO and a route for the fabrication of eco-friendly biobased polyurethane microfibers from aqueous dispersions.     

Technology of electrostatic spinning for the production of polyurethane tissue engineering scaffolds

Electrostatic spinning was investigated as an alternative to electrospinning to establish the potential of the technique for the production of a range of microfibrous polyurethane scaffolds with a variety of structures and properties related to the fabrication conditions. Tecoflex^® SG‐80A polyurethane was spun, systematically altering the spinning parameters, and the resulting scaffolds were characterised using scanning electron microscopy. Inter‐fibre separation was significantly affected by flow rate, spray distance and grid and mandrel voltages; fibre diameter by flow rate and mandrel voltage; void fraction by flow rate; fibre orientation by traverse speed and mandrel speed; and thickness by flow rate. Thus, scaffold (three‐dimensional) architecture may be controlled through manipulation of the electric fields and the fibre deposition (spinning parameters of flow rate and grid and mandrel voltages); and by spray movement and direction (spinning parameters of relative spray height, spray distance, traverse speed and mandrel speed). There were significant differences between the internal and external scaffold surfaces, due in part to the manner in which the surface of the mandrels was prepared. We conclude that the process may be used to produce a range of polyurethane scaffolds for use in many tissue engineering applications. Copyright © 2007 Society of Chemical Industry     

静电纺丝抗菌聚氨酯纳米纤维的结构与性能

在聚氨酯/四氢呋喃-N,-二甲基甲酰胺(PU/THF-DMF)溶液中分别添加质量分数为5%的TiO_2-Ag,HM-98,三氯均二苯胺(TCC),4-氯-3,5-二甲基苯酚(PCMX),2,4,4'-三氯-2'-羟基二苯酚(DP 300),ε-聚赖氨酸(ε-PLYS)抗菌剂通过静电纺丝技术制备了PU抗菌纳米纤维,并对其性能和结构进行了研究。结果表明:含ε-PLYS,HM-98,TiO_2-Ag,DP300抗菌剂的抗菌PU纳米纤维对金黄色葡萄球菌和大肠杆菌的抗菌效果较为优良,抗菌率均达到了99.9%以上,TCC、PCMX抗菌剂的抗菌效果较差;添加HM-98抗菌剂降低了纺丝溶液的可纺性,但纤维直径有所下降;抗菌剂在PU中的分散性好。     

Dry‐jet‐wet spun polyurethane fibers. I. Optimization of the spinning parameters

This study examined the spinning of polyurethane‐based elastomeric fibers with the dry‐jet‐wet spinning method. The three important spinning variables that were chosen were the coagulation bath ratio (dimethylformamide/water), the bath temperature, and the stretch ratio. A three‐variable factorial design method, proposed by Box and Behnken, was used to optimize these process parameters. The spinning process was further fine‐tuned by the variation of the stretch ratio and the dope solid content. The effect of the dry‐jet length on the fiber properties was also studied. The tenacity and elastic recovery properties of the fibers were found to be optimum at a bath ratio (dimethylformamide/water) of 60 : 40, a bath temperature of 15°C, and a stretch ratio of 2.5. The density and sonic modulus were measured to determine the effect of varying the process variables on structural parameters such as the density and orientation. The surface morphological features, as revealed by scanning electron microscopy, were correlated to the fiber properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

热处理时间对熔纺聚氨酯纤维性能的影响

讨论预聚体法生产的熔纺酯型聚氨酯纤维在 80℃下热处理时间对其性能的影响。结果表明 :该纤维的热处理一段时间后线密度随热处理时间的增加而增加 ,强度开始随热处理时间增加而提高 ,但随着时间进一步增加而下降 ;断裂伸长率 ,沸水收缩率随热处理时间的增加而降低 ,热处理时间对纤维的干热和湿热收缩率影响不大     

Fabricating and robust artificial neural network modeling nanoscale polyurethane fiber using electrospinning method

With regard to the fact that currently there is no comprehensive method to predict diameter of polyurethane/solvent fiber from electrospinning, in this study, diameter prediction of polyurethane/solvent fiber was conducted using neural networks and an error of 166 nm was observed. This error shows that artificial neural networks (ANNs) can predict diameter of electrospinning polyurethane fibers well. Then, considering weak repeatability nature of electrospinning in fabricating fibers with desired diameter, least mean square is used to improve stability of neural network model that shows an error of 113 nm, which represented better results compared to common ANN. To investigate the effect of each one of parameters affecting fiber diameter, sensitivity analysis was conducted. Along with this predicting model, sensitivity analysis can be used to reduce parameters space before conducting future studies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45116.     

电纺法制备TPU微/纳米纤维的研究进展

本文介绍了电纺热塑性聚氨酯(TPU)制备中所涉及熔融电纺法和溶液电纺法的研究现状,并综述了电纺TPU在医用支架材料、伤口敷料、锂电池电解质、形状记忆材料、吸声材料、压阻敏感性材料方面的应用研究进展。     

Poly(lactic acid) fibers obtained by solution blow spinning: Effect of a greener solvent on the fiber diameter

Poly(lactic acid) (PLA) fibers has been obtained by solution blow spinning (SBS) using different solvents, however most of them are toxic and can be dangerous to human health or cause harm to the environment. Therefore, this work aimed to evaluate the use of dimethyl carbonate (DMC), a greener solvent, on the production of PLA fibers by SBS using surface response analysis to evaluate and compare the influence of three solvents (chloroform, DMC, and 1,1,1,3,3,3‐hexafluoro‐2‐propanol, HFP) in the average fiber diameter. Scanning electron microscopy (SEM) was used to analyze the fiber morphology and different ranges of fiber diameter was observed when varying the solvents (chloroform: 260–970 nm; DMC: 240–650 nm; and HFP: 220–470 nm). Regression analysis showed the polymer concentration was significant for all solvents and the air pressure was significant when using chloroform and HFP. Regardless of the air pressure, increasing the PLA concentration increased the average fiber diameters for all solvents. Chloroform and HFP indicated a tendency of reduction on the average fiber diameter when the air pressure was decreased, however this behavior was not observed for DMC. It was also observed that the standard deviation indicated to be more affected by the polymer concentration than by the air pressure. The results also indicated that lower surface tension and viscosity can reduce fiber thickness. All solvents showed to be feasible to produce PLA fibers by SBS and DMC can be used to produce PLA fibers with an affordable price using a greener process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43379.     

Bio-inspired acid-sensitive polyurethane woven artificial muscle nanofibers with tunable mechanical properties via electrostatic spinning

Polyurethane (PU) is a traditional chemical known for its chemical stability and mechanical performance. Inspired by the similarity between the formation and breakage of chemical coordination bonds and the energy storage and release of muscle fibers, muscle-like electrostatically spun fibers with acid-responsive energy storage and release were prepared by introducing bio-inspired elastic energy storage groups and bio-active degradation groups (PU-BPY-Fe) in the main chain of PU, taking advantage of the good mechanical properties of PU. The fabricated electrospinning film PU-BPY-Fe can respond to external stimulation, which generated high strain (32 MPa), stretch of 206%, outperforming the nanofiber membrane before stimulation, similar and even higher than the biological muscles. The variable mechanical properties and elastic energy storage capacity of PU-BPY-Fe were attributed to the reversible hydrogen bonding and the destabilization of metal coordination bonds (Fe³⁺ to Fe²⁺) within the material under acidic stimulation. Cytotoxicity testing of the synthesized fibers indicated a degree of biocompatibility, suggesting potential for in vivo applications. This method of storing and releasing elastic energy was demonstrated and has endowed the PU-BPY-Fe with stimuli-responsibility and muscle-like mechanical properties, which may inspire the design of soft muscles materials for robots and tissue engineering applications.     

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.     

Electrospinnability of poly(butylene succinate): Effects of solvents and organic salt on the fiber size and morphology

Submicrosized and nanosized fibers of polymers can be formed easily by electrospinning techniques. However, bead formation can occur if inappropriate solvent systems are used. In this study, we focused on investigating the effects of solvents and organic salt on the electrospinnability of poly(butylene succinate) (PBS). Electrospun PBS fibers were obtained from single‐solvent systems, that is, systems with chloroform (CF) or dichloromethane, at various concentrations (8–30% w/v). Discrete beads and beaded fibers were still found at every PBS concentration. In this study, the electrospinnability of the PBS solutions in CF were improved by the addition of methanol (MeOH) as a cosolvent and an organic salt [alkyl ammonium ethyl sulfate (AAES)]. The obtained fibers were smooth without any beads, and the diameters were affected by the amount of MeOH and the PBS concentration. The electrospinnability of PBS could be enhanced by the addition of a cosolvent with a high dielectric constant or organic salt (AAES). Moreover, the diameters of the electrospun PBS fibers decreased with increasing AAES concentration. We found that the presence of MeOH (30 vol %) and the addition of AAES caused an increase in the crystallinity of the PBS fibers. Therefore, we concluded that bead‐free ultrafine PBS fibers could be obtained through the addition of the cosolvent and the organic salt. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42716.     

Neem oil encapsulated electrospun polyurethane nanofibrous bags for seed storage: A step toward sustainable agriculture

For higher crop yields, availability of good quality healthy seeds is a major challenge which is directly related to post-harvesting proper seed storage. Various reasons for significant seed storage losses includes varying temperature, humidity and presence of rodents, insects and microbial infestation. In this study, a new type of seed storage bag is produced using electrospun polyurethane (PU) nanofibers encapsulated with neem oil. The effect of neem oil loading (3, 5, and 10% w/v) on fiber morphology, wettability, and water vapor permeability is studied. The interaction of neem oil with PU is investigated and correlated with thermal stability and mechanical strength. The physico-mechanical characteristic then compared with commercial polypropylene storage bags to confirm its applicability. The real time storage experiment carried out for 75 days infers that 90% seeds stored in nanofibrous bags were uninfected, whereas 70% seeds in commercial bags found to be infected with storage fungi. These nanofabric bags show a great potential toward reducing seed storage losses and may be a game changer for achieving food security as one of the goal for sustainable development.     

Study on the effect of inorganic salts on the alignment of electrospun fiber

Well‐aligned and highly ordered architectures are always required in many fields, such as tissue engineering, electronics, and preparation of composite materials. In this study, electrospun mats with well‐aligned fibers and various fiber assemblies were successfully fabricated by electrospinning of poly(vinylbutyral) (PVB)/inorganic salt solution under the optimal salt condition. Then, the effect of inorganic salts on the degree of electrospun fiber alignment was comprehensively investigated, and the results indicated that the viscosity and conductivity of the solutions were the key factors influencing the degree of fiber alignment. It was expected that this simple and feasible method could be helpful for the fabrication of the well‐aligned electrospun fibers and various fiber assemblies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of solvent on morphology of electrospinning ethyl cellulose fibers

The influence of the composition of a multicomponent solvent on the surface morphology and diameter distribution of ethyl cellulose fibers produced by electrospinning technology was investigated. The results showed that the average diameter of the fibers using the multicomponent solvent was thinner than when using either of the two components and the diameter distribution of the fibers became narrower. Tiny tubercles formed on the fiber surface, which may improve the specific surface area and broaden the applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1292–1297, 2005     

Evolution of polyacrylonitrile precursor fibers and the effect of stretch profile in wet spinning

Wet spinning of polyacrylonitrile-based polymers is a common technique to manufacture carbon fiber precursors. Understanding the role of stretch profile on structural evolution will support efforts to reduce cost and improve process robustness. Fiber stretch generally occurs in three sequential stages: jet stretch, wet stretch (first draw), and hot draw (second draw). In this study, total fiber stretch was kept constant, but distributed differently across the stretch stages yielding three different fiber variants. Samples were collected and analyzed after each stretch stage in order to correlate process parameters to structural information. For all variants, orientation of the ordered phase increases gradually for each stage of stretch while activation energy for the structural relaxation decreases. Alternatively, crystallite size increases substantially during hot draw, which is shown to have the most pronounced effect on cyclization behavior. Given the process conditions, the variant with the lowest jet stretch and highest hot draw demonstrates the highest tenacity and modulus along with the greatest orientation, crystallite size, and highest peak exotherm temperature.     

聚氨酯的静电纺丝

简述了聚氨酯(PU)的特性;分析了PU静电纺丝的可纺性影响因素;论述了静电纺丝PU纤维的特性及应用领域。指出PU具有较好的可纺性,PU纤维具有优异的力学性能,应用前景广阔。建议PU静电纺丝应从静电纺丝工艺参数、利用静电纺丝制备组织工程支架、纤维抗菌功能改性等方面进行更深入的研究。     

Melt‐electrospun fibers obtained from polypropylene/poly(ethylene‐co‐vinyl alcohol)/polypropylene three‐layer films

Production of polypropylene (PP) nanofibers below 1 μm in average diameter is difficult with conventional melt‐spinning. A nozzle‐free melt‐type electrospinning (M‐ESP) system with a line‐like CO₂ laser beam melting device were used to produce PP nanofibers. To achieve the purpose, core [poly(ethylene‐co‐vinyl alcohol) (EVOH)]–clad (PP) nanofibers (average diameter, 0.88 μm) were fabricated from PP/EVOH/PP three‐layer films using the M‐ESP. The core–clad structure was formed by a wrapping phenomenon caused by the difference in the melt flow rates (MFRs) of PP and EVOH melts. Hollow PP nanofibers were obtained from the core–clad nanofibers by extraction of EVOH. Nanofiber diameter and hollow wall thickness could be altered by changing the MFR of the PP melt. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46393.     

Electrospinning of gelatin fibers using solutions with low acetic acid concentration: Effect of solvent composition on both diameter of electrospun fibers and cytotoxicity

Gelatin fibers were prepared by electrospinning of gelatin/acetic acid/water ternary mixtures with the aim of studying the feasibility of fabricating gelatin nanofiber mats at room temperature using an alternative benign solvent by significantly reducing the acetic acid concentration. The results showed that gelatin nanofibers can be optimally electrospun with low acetic acid concentration (25%, v/v) combined with gelatin concentrations higher than 300 mg/mL. Both gelatin solutions and electrospun gelatin mats (prepared with different acetic acid aqueous solutions) were analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry techniques to determine the chemical and structural changes of the polymer. The electrospun gelatin mats fabricated from solutions with low acetic acid content showed some advantages as the maintenance of the decomposition temperature of the pure gelatin (～ 230°C) and the reduction of the acid content on electrospun mats, which allowed to reach a cell viability upper than 90% (analyzed by cell viability test using human dermal fibroblast and embryonic kidney cells). This study has also analyzed the influence of gelatin and acetic acid concentration both on the solution viscosity and the electrospun fiber diameter, obtaining a clear relationship between these parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42115.     

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     

溶胶纺丝法制备氧化锆纤维研究进展

溶胶凝胶法制备可纺性锆溶胶的常见体系以及几种纺丝方法,并对其进行了对比;对凝胶纤维的热处理进行了阐述,强调了气氛预烧结的重要性。