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Charge generation, charge transport, and residual charge in the electrospinning of polymers: A review of issues and complications

Collins, George; Federici, John; Imura, Yuki; Catalani, Luiz Henrique
Fonte: AMER INST PHYSICS; MELVILLE Publicador: AMER INST PHYSICS; MELVILLE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.71%
Electrospinning has become a widely implemented technique for the generation of nonwoven mats that are useful in tissue engineering and filter applications. The overriding factor that has contributed to the popularity of this method is the ease with which fibers with submicron diameters can be produced. Fibers on that size scale are comparable to protein filaments that are observed in the extracellular matrix. The apparatus and procedures for conducting electrospinning experiments are ostensibly simple. While it is rarely reported in the literature on this topic, any experience with this method of fiber spinning reveals substantial ambiguities in how the process can be controlled to generate reproducible results. The simplicity of the procedure belies the complexity of the physical processes that determine the electrospinning process dynamics. In this article, three process domains and the physical domain of charge interaction are identified as important in electrospinning: (a) creation of charge carriers, (b) charge transport, (c) residual charge. The initial event that enables electrospinning is the generation of region of excess charge in the fluid that is to be electrospun. The electrostatic forces that develop on this region of charged fluid in the presence of a high potential result in the ejection of a fluid jet that solidifies into the resulting fiber. The transport of charge from the charge solution to the grounded collection device produces some of the current which is observed. That transport can occur by the fluid jet and through the atmosphere surrounding the electrospinning apparatus. Charges that are created in the fluid that are not dissipated remain in the solidified fiber as residual charges. The physics of each of these domains in the electrospinning process is summarized in terms of the current understanding...

Desenvolvimento de membranas compósitas de poliuretano pelo processo de eletrofiação.; Development of polyurethane composite membranes by electrospinning process.

Harada, Nikolas Sinji
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/06/2014 PT
Relevância na Pesquisa
56.45%
O presente trabalho tem por objetivo o desenvolvimento de um novo material nanocompósito com propriedades biocidas, alta porosidade e alta permeabilidade ao ar, possibilitando sua aplicação na área biomédica. Neste trabalho, foram desenvolvidas membranas compósitas de poliuretano termoplástico (TPU) contendo prata (Ag) e óxido de zinco (ZnO), a partir da evaporação de soluções durante o processo de eletrofiação. Mediu-se as propriedades de viscosidade e de condutividade elétrica das soluções preparadas para eletrofiação. Avaliou-se a modificação da morfologia do material pelo uso de vários solventes em diferentes concentrações. Uma morfologia mais uniforme das membranas contendo fibras eletrofiadas foi obtida com o sistema de solventes tetra-hidrofurano (THF) e dimetilformamida (DMF), na proporção de 50:50. A avaliação da morfologia e da distribuição da fase dispersa inorgânica nas membranas foi efetuada utilizando-se microscopia ótica (MO) e microscopia eletrônica de varredura (MEV), e a formação de fibras com diâmetros na faixa de 250 a 800 nanômetros foi observada. As fases dispersas apresentaram-se distribuídas na membrana, sem a presença de regiões de aglomeração. A presença de prata ou de óxido de zinco nas membranas eletrofiadas foi confirmada através da espectroscopia de energia dispersiva de raios- X (EDS) e por difratometria de raios-X. As propriedades bactericidas das membranas compósitas de TPU/ZnO e TPU/Ag foram avaliadas e estabelecidas em testes com as bactérias S. aureus e K. pneumoniae. O teste de citotoxicidade das membranas de TPU foi executado e numa avaliação inicial foi observada a sua biocompatibilidade.; The aim of this study is to develop nanostructured polyurethane composite membranes which have antibacterial properties...

Desenvolvimento e caracterização de nanofibras de acetato de celulose para liberação controlada de fármacos; Development and characterization of cellulose acetate nanofibers for controlled release of drugs

Silvia Vaz Guerra Nista
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/02/2012 PT
Relevância na Pesquisa
36.6%
Este projeto foi desenvolvido em duas fases, usando a tecnologia de eletrofiação. A primeira fase foi dedicada a obtenção de membranas eletrofiadas com acetato de celulose, as quais formaram nanofibras que foram carregadas com Sulfato de gentamicina, na segunda fase, para estudos da liberação controlada deste fármaco. Na primeira fase as membranas de nanofibras de Acetato de Celulose, chamadas de nanomembranas, foram produzidas utilizando-se quatro misturas de solventes (Acido Acético/Água (75:25 m/m), Acetona/Água (85:15 m/m), Dimetilacetamida (DMAc)/Acetona (1:2 m/m), Dimetilacetamida/Acetona/Água (32/63/5 m/m)). Usando a ferramenta de planejamento de experimentos (DOE), foram definidos os melhores parâmetros para preparação das membranas nanoestruturadas, em cada sistema de solvente. Três variáveis, sendo a distância entre a agulha e o coletor, a concentração de acetato de celulose na solução e a tensão aplicada, em dois níveis (alto e baixo), foram estudadas em cada sistema. As respostas avaliadas para obtenção da melhor condição, em cada caso, foram o diâmetro médio da fibra obtida e aspecto da membrana formada. Foi realizado também, no sistema de solvente Acido Acético/Água (70:30 m/m), um comparativo entre fiação horizontal...

Instalação da tecnologia de electrospinning para a produção e caracterização de nanofibras de celulose incorpodadas com óleos naturais; Installation of electrospinning technology for production and characterization of cellulose nanofibers embedded with essencial oils

Ana Luiza Garcia Millás
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/07/2012 PT
Relevância na Pesquisa
46.55%
A ciência dos biomateriais e a nanotecnologia caminham juntas em busca de novas alternativas e da melhoria das propriedades físicas, químicas e mecânicas dos materiais, relacionadas à alta razão superfície/volume e às dimensões nanométricas que possibilitam obter ótimo desempenho com pouca quantidade de material. Esse trabalho objetivou a produção de nanofibras biodegradáveis e biocompatíveis a partir da solução de acetato de celulose a 10(%m/m) dissolvido em sistema de acetona e água (4:1). A pesquisa partiu da instalação de um equipamento de electrospinning e do estudo dos parâmetros que influenciam o processo e a formação de nanofibras através dessa tecnologia. Concentrações entre 1% e 15% dos óleos naturais das espécies Copaifera langsdorffii e Cymbopogon nardus com comprovadas propriedades cicatrizantes, analgésicas, antimicrobianas e de repelência a insetos foram misturadas a solução de acetato de celulose e estudou-se a influência desses compostos sobre o processo de eletrofiação e a estrutura das fibras confeccionadas. Com foco no óleo de copaíba verificou-se por cromatografia gasosa a sua presença nas nanofibras e foram feitos testes preliminares de viabilidade celular e biocompatibilidade in vitro. A intenção futura dessa pesquisa é a aplicação desse material na área da medicina regenerativa de tecidos...

Nanocompósitos poliméricos obtidos por freeze-casting e eletrofiação; Polymer nanocomposites obtained by freeze-casting and electrospinning

Lucimara Lopes da Silva
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/10/2013 PT
Relevância na Pesquisa
46.51%
Neste trabalho, examinou-se o comportamento de dispersões aquosas de látex e seus nanocompósitos com argila, quando submetidos aos processos de moldagem por liofilização (freeze-casting) e eletrofiação (electrospinning). Os sólidos resultantes foram caracterizados principalmente por microscopia eletrônica de varredura (MEV). Através do freeze-casting do látex poli(estireno-co-acrilato de butila-co-ácido acrílico (P(S-BA-AA)) foi obtido um monolito de baixa densidade com variadas morfologias de poros (colunares, alongados e lamelares) e predominância de poros com morfologia do tipo espinha de peixe, semelhantes a "shish-kebabs" encontrados em polímeros semicristalinos. A moldagem por liofilização de espumas líquidas de látex com e sem argila originou espumas sólidas que apresentaram hierarquia de poros, com poros menores orientados sobre cavidades maiores, derivadas de bolhas de ar. As diferentes morfologias obtidas são modeladas pelo gelo, cujo hábito cristalino experimenta diversas transições morfológicas durante o processo de congelamento, devido às instabilidades térmicas na interface sólido-líquido (S/L). A técnica de eletrofiação permitiu obter fibras de blendas poliméricas imiscíveis e fibras nanocompósitas a partir de uma dispersão aquosa de látex poli(estireno-acrilato de butila) (P(S-BA)) misturada com soluções aquosas de poli(óxido de etileno) (PEO) de diferentes massas molares e argila. As fibras poliméricas apresentaram morfologia coaxial...

Biodegradable nanomats produced by electrospinning : expanding multifunctionality and potential for tissue engineering

Ashammakhi, N.; Ndreu, A.; Piras, A. M.; Nikkola, L.; Sindelar, T.; Ylikauppila, H.; Harlin, A.; Gomes, Manuela E.; Neves, N. M.; Chiellini, E.; Chiellini, F.; Hasirci, Vasif; Redl, Heinz; Reis, R. L.
Fonte: American Scientific Publishers Publicador: American Scientific Publishers
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
Relevância na Pesquisa
46.42%
With increasing interest in nanotechnology, development of nanofibers (n-fibers) by using the technique of electrospinning is gaining new momentum. Among important potential applications of n-fiber-based structures, scaffolds for tissue-engineering represent an advancing front. Nanoscaffolds (n-scaffolds) are closer to natural extracellular matrix (ECM) and its nanoscale fibrous structure. Although the technique of electrospinning is relatively old, various improvements have been made in the last decades to explore the spinning of submicron fibers from biodegradable polymers and to develop also multifunctional drug-releasing and bioactive scaffolds. Various factors can affect the properties of resulting nanostructures that can be classified into three main categories, namely: (1) Substrate related, (2) Apparatus related, and (3) Environment related factors. Developed n-scaffolds were tested for their cytocompatibility using different cell models and were seeded with cells for to develop tissue engineering constructs. Most importantly, studies have looked at the potential of using n-scaffolds for the development of blood vessels. There is a large area ahead for further applications and development of the field. For instance...

Patterning of polymer nanofiber meshes by electrospinning for biomedical applications

Neves, N. M.; Campos, R.; Pedro, A. J.; Cunha, J.; Macedo, F.; Reis, R. L.
Fonte: DOVEPress Publicador: DOVEPress
Tipo: Artigo de Revista Científica
Publicado em //2007 POR
Relevância na Pesquisa
46.28%
The end-product of the electrospinning process is typically a randomly aligned fiber mesh or membrane. This is a result of the electric field generated between the drop of polymer solution at the needle and the collector. The developed electric field causes the stretching of the fibers and their random deposition. By judicious selection of the collector architecture, it is thus possible to develop other morphologies on the nanofiber meshes. The aim of this work is to prepare fiber meshes using various patterned collectors with specific dimensions and designs and to evaluate how those patterns can affect the properties of the meshes relevant to biomedical applications. This study aims at verifying whether it is possible to control the architecture of the fiber meshes by tailoring the geometry of the collector. Three different metallic collector topographies are used to test this hypothesis. Electrospun nonwoven patterned meshes of polyethylene oxide (PEO) and poly(ε-capro-lactone) (PCL) were successfully prepared. Those fiber meshes were analyzed by scanning electron microscopy (SEM). Both mechanical properties of the meshes and cell contacting experiments were performed to test the effect of the produced patterns over the properties of the meshes relevant for biomedical applications. The present study will evaluate cell adhesion sensitivity to the patterns generated and the effect of those patterns on the tensile properties of the fiber meshes.

Electrospinning : processing technique for tissue engineering scaffolding

Martins, A.; Reis, R. L.; Neves, N. M.
Fonte: Maney Publicador: Maney
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
56.45%
Electrospinning has attracted tremendous interest in the research community as a simple and versatile technique to produce synthetic polymeric ultrafine fibres with diameters ranging from a few micrometres to tens of nanometres. Recently, some natural origin polymers have also been successfully electrospun. Owing to their very small diameter, polymeric nanofibres exhibit unusual properties such as high specific surface area, flexibility in surface functionalities and superior mechanical properties. In addition, electrospun non-woven meshes could physically mimic the extracellular matrix structure of native tissues. These remarkable properties render electrospun nanofibres useful for many applications, particularly those related to the field of biomedical engineering. The first part of this review is intended to provide a fundamental survey of the electrospinning process (apparatus, governing parameters) and of recent improvements of the technique, including associated structural modifications of polymeric nanofibre meshes. The prospective tissue engineering/biomedical applications of electrospun polymeric nanofibres are then reviewed, namely, wound dressings, medical prostheses, drug delivery systems, DNA release and tissue engineering scaffolds. The essential properties of scaffolds in terms of the structural features of electrospun nanofibre meshes are discussed. Finally...

Characterization of an electrospinning process using different PAN/DMF concentrations

Gomes,Demetrius S.; Silva,Ana N. R. da; Morimoto,Nilton I.; Mendes,Luiz T. F.; Furlan,Rogerio; Ramos,Idalia
Fonte: Associação Brasileira de Polímeros Publicador: Associação Brasileira de Polímeros
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2007 EN
Relevância na Pesquisa
56.46%
We performed an extensive characterization of an electrospinning process to evaluate how the process parameters and precursor solution characteristics affect the fibers morphology. The work was conducted using precursor solutions with different concentrations of polyacrylonitrile (PAN) diluted in a fixed amount of N,N/dimethylformamide (DMF). Fibers obtained with this process can find important applications in the field of nanosensors. The characteristics of the electrospun fibers were analyzed as a function of the solution viscosity, applied voltage and distance between the needle tip (positive electrode) and the collector plate (grounded electrode). The electrical current was monitored during the deposition process and its behavior was correlated with the characteristics of the fibers obtained. Our results demonstrate that the diameter of the fibers increases with increasing viscosity and applied voltage. The number of deposited fibers also increases with the applied voltage. Also, viscosity and applied voltage strongly affect the shape, length and morphology of the fibers. Of particular interest, we demonstrated that by monitoring the electrical current it is possible to control the fibers morphology and bead concentration. The distance between tip and collector plate determines the way the fibers arrive on the collector plate. A main contribution of this study was the definition of conditions to controllably obtain fibers that are smooth and that present diameters in the range between 140 and 300 nm.

Fabrication and characterization of nanofibrous scaffold developed by electrospinning

Dhandayuthapani,Brahatheeswaran; Yasuhiko,Yoshida; Maekawa,Toru; Kumar,D. Sakthi
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2011 EN
Relevância na Pesquisa
46.45%
Electrospinning has been recognized as an efficient technique for the forming of polymer nanofibers. Silk fibroin (SF) nanofibers were electrospun from SF solution using trifluoroacetic acid solution as a solvent. In the present work, we have systematically evaluated the effects of instrument parameters, including applied voltage, tip-target distance, solution flow rate, solution parameters; such as polymer concentration and solution viscosity on the morphology of electrospun SF fibers. The applied voltage and flow rate was monitored at fixed tip target distance during the electrospinning process and it was correlated with the characteristics of the fibers obtained. The number of deposited fibers also increases with the applied voltage. Also, viscosity, flow rate and applied voltage strongly affect the shape and morphology of the fibers. A particular interest, we demonstrated that by monitoring the applied voltage and flow rate it is possible to control the fibers morphology and bead concentration. Rheological study showed a strong dependence of spinnability and fiber morphology on solution viscosity. Solution concentrations has been found to most strongly affect fiber size, with fiber diameter increasing with increasing solution concentration and the morphology of the deposition on the collector changed from spherical beads to interconnected fibrous networks. FTIR analysis clearly shows that there are no spectral differences between fibers and which suggests that there was no chemical modification developed during the process. Under optimized conditions...

Nanocomposites of polyamide 6/residual monomer with organic-modified montmorillonite and their nanofibers produced by electrospinning

Beatrice,Cesar Augusto Gonçalves; Santos,Camila Ribeiro dos; Branciforti,Marcia Cristina; Bretas,Rosario Elida Suman
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
46.37%
Nanocomposites of an organic-modified montmorillonite (MMT) and polyamide 6 (PA6) with a residual monomer were produced by melt mixing in a torque rheometer. By wide angle X-rays diffraction (WAXD), intercalated/exfoliated structures were observed in the PA6/MMT nanocomposites with 3 and 5 wt. (%) of MMT; on the other hand, when 7 wt. (%) of MMT was added, a nanocomposite with exfoliated structures was obtained due to the predominant linking reactions between the residual monomer and the "nanoclays" organic surfactant. Solutions of these PA6/MMT nanocomposites at 15, 17 and 20 wt. (%) in formic acid were prepared. The 3 and 5 wt. (%) nanocomposites were successfully electrospun; however, electrospinning of the 7 wt. (%) nanocomposite was not possible. WAXD, scanning and transmission electron microscopy results showed that the 3 and 5 wt. (%) nanofibers with average diameter between 80-250 nm had exfoliated structures. These results indicate that the high elongational forces developed during the electrospinning process changed the initial intercalated/exfoliated structure of the nanocomposites to an exfoliated one.

Spray deposition of live cells throughout the electrospinning process produces nanofibrous three-dimensional tissue scaffolds

Seil, Justin T; Webster, Thomas J
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.28%
Compared with traditional in-vitro cell culture materials, three-dimensional nanofibrous scaffolds provide a superior environment for promoting cell functions. Since nanofibrous scaffolds have nanometer pore sizes, cells are unable to penetrate on their own, so must be incorporated into the scaffold during fabrication to ensure proper cell distribution. In this study, biodegradable and cytocompatible poly(DL-lactide-co-glycolide) (PLGA) nanofibers were produced using an electrospinning process. As a model cell line, fibroblasts were periodically sprayed from a pump-action spray bottle onto the developing scaffold. The viability of cells before and after spraying, and also after incorporation into the scaffold, was compared. Results indicated that cell spraying and the scaffold fabrication process did not significantly reduce cell viability. These findings, thus, contribute to the understanding of how to produce more physiological relevant cell-seeded nanofibrous scaffolds, an important element for the future of nanotechnology and tissue engineering.

Drug-Loaded Zein Nanofibers Prepared Using a Modified Coaxial Electrospinning Process

Huang, Weidong; Zou, Tao; Li, Shengfang; Jing, Jinqiu; Xia, Xianyou; Liu, Xianli
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 21/03/2013 EN
Relevância na Pesquisa
46.5%
This study investigated the preparation of drug-loaded fibers using a modified coaxial electrospinning process, in which only unspinnable solvent was used as sheath fluid. With zein/ibuprofen (IBU) co-dissolving solution and N, N-dimethylformamide as core and sheath fluids, respectively, the drug-loaded zein fibers could be generated continuously and smoothly without any clogging of the spinneret. Field emission scanning electron microscopy and transmission electron microscopy observations demonstrated that the fibers had ribbon morphology with a smooth surface. Their average diameters were 0.94 ± 0.34 and 0.67 ± 0.21 μm when the sheath-to-core flow rate ratios were taken as 0.11 and 0.25, respectively. X-ray diffraction and differential scanning calorimetry verified that IBU was in an amorphous state in all fiber composites. Fourier transform infrared spectra showed that zein had good compatibility with IBU owing to hydrogen bonding. In vitro dissolution tests showed that all the fibers could provide sustained drug release files via a typical Fickian diffusion mechanism. The modified coaxial electrospinning process reported here can expand the capability of electrospinning in generating fibers and provides a new manner for developing novel drug delivery systems.

Tunable biphasic drug release from ethyl cellulose nanofibers fabricated using a modified coaxial electrospinning process

Li, Chen; Wang, Zhuan-Hua; Yu, Deng-Guang; Williams, Gareth R
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em 23/05/2014 EN
Relevância na Pesquisa
46.24%
This manuscript reports a new type of drug-loaded core-shell nanofibers that provide tunable biphasic release of quercetin. The nanofibers were fabricated using a modified coaxial electrospinning process, in which a polyvinyl chloride (PVC)-coated concentric spinneret was employed. Poly (vinyl pyrrolidone) (PVP) and ethyl cellulose (EC) were used as the polymer matrices to form the shell and core parts of the nanofibers, respectively. Scanning and transmission electron microscopy demonstrated that the nanofibers had linear morphologies and core-shell structures. The quercetin was found to be present in the nanofibers in the amorphous physical status, on the basis of X-ray diffraction results. In vitro release profiles showed that the PVP shell very rapidly freed its drug cargo into the solution, while the EC core provided the succedent sustained release. Variation of the drug loading permitted the release profiles to be tuned.

Electrospinning of polymeric nanofiber materials : process characterization and unique applications

Yu, Jian Hang, Ph. D. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 156 p.
ENG
Relevância na Pesquisa
36.76%
Electrospinning or electrostatic fiber spinning employs electrostatic force to draw a fiber from a spinneret. This fiber solidifies and lies down on a collector in the form of a non-woven fiber mat. Electrospinning has attracted much attention recently due to the ease with which fine fibers about 10 nanometers to 10 microns in diameter can be produced from both natural and synthetic polymers. Despite the large volume of publications on this technology, few publications discuss the mechanics of electrospinning. Most publications deal with the exploratory works on what material can be electrospun and the potential applications of the electrospun fibers. This work examined the electrohydrodynamics of the electrospinning process and developed this technology for making functional materials. The first part of this dissertation deals with the electrohydrodynamics of the process. The effects of processing parameters and material properties on the size and structure of electrospun fibers were studied. The experimental findings validated the analytical scaling model developed by Fridrikh and co-workers to predict how the final radius or "the terminal jet radius" of the electrospun fiber depends on the processing parameters.; (cont.) The scaling formula is derived from the force balance between surface tension and surface charge repulsion. The scaling model provides a powerful tool for controlling the fiber diameter just by adjusting the surface tension...

Preparação e caracterização de nanofibras da blenda PLLA/PCL obtidas pelos processos de eletrofiação e rotofiação; Preparation and characterization of nanofibrous of PLLA/PCL blend by electrospinning and rotary jet spinning processes

Talita Almeida Vida de Brito
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/07/2013 PT
Relevância na Pesquisa
36.64%
Este trabalho apresenta a preparação e caracterização de nanofibras da blenda poli (L-ácido láctico) (PLLA)/poli (Ɛ-caprolactona) (PCL) através dos processos de eletrofiação e rotofiação destinada à produção de fibras visando futuras aplicações como suporte para a engenharia tecidual. As blendas foram preparadas através da dissolução do polímero em clorofórmio e clorofórmio mais acetona, resultando em uma solução de 6%. A eletrofiação é um processo relativamente simples e de baixo custo, que consiste na aceleração de uma solução polimérica, inicialmente contida em um capilar metálico, pela presença de um campo elétrico externo, para produzir fibras com diâmetro médio reduzido. Apesar da popularidade e da versatilidade, o processo de eletrofiação apresenta algumas desvantagens, tais como o uso de fonte de alta tensão, baixa taxa e longo tempo de produção das fibras. Com a necessidade de encontrar um método de produção de fibras para sanar eventuais obstáculos encontrados na eletrofiação, foi realizado um estudo com um novo processo: a rotofiação. O processo de rotofiação é um processo simples que forma fibras durante o jateamento da solução polimérica através de um orifício central utilizando alta velocidade de rotação e não utiliza campo elétrico de alta voltagem...

Non-woven nanofiber chitosan/peo membranes obtained by electrospinning

Bizarria,M. T. M.; d'Ávila,M. A.; Mei,L. H. I.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2014 EN
Relevância na Pesquisa
46.5%
The present work focused on the preparation and morphological characterization of chitosan-based nanofiber membranes, aiming at applications in medical and pharmacological areas. Membranes with nanofiber diameters ranging from 50 - 300 nm were prepared from polymer solutions through the electrospinning process. To stabilize the process, it was necessary to use poly(ethylene oxide) (PEO), which is a biocompatible synthetic polymer. Pure chitosan solutions, as well as chitosan and PEO solution blends, were characterized by their rheological behavior, conductivity, and surface tension measurements. The electrospun fiber thermal characteristics and crystalline structures were investigated through thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Scanning electron microscopy images (SEM) were used for the morphological evaluations of the membranes. The addition of PEO to the chitosan solutions improved their electrical conductivity, surface tension and viscosity, greatly favoring the electrospinning process. Thus, membranes with 80% chitosan could be electrospun.

Effects of non-linear rheology on the electrospinning process: a model study

Pontrelli, Giuseppe; Gentili, Daniele; Coluzza, Ivan; Pisignano, Dario; Succi, Sauro
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.37%
We develop an analytical bead-spring model to investigate the role of non-linear rheology on the dynamics of electrified jets in the early stage of the electrospinning process. Qualitative arguments, parameter studies as well as numerical simulations, show that the elongation of the charged jet filament is significantly reduced in the presence of a non-zero yield stress. This may have beneficial implications for the optimal design of future electrospinning experiments.

Investigation of Linear Electrospinning Jets

Knopf, Jeffrey A.
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Undergraduate Thesis
Relevância na Pesquisa
46.59%
Norman Wagner; Electrospinning, the process of creating polymeric nanofibers through the use of an electric charge, has attracted significant research recently due to the numerous potential applications of the fibers, such as tissue scaffolds, multi-functional composites, filtration devices, and sensors. One major issue with the process is the lack of a functional model that can link processing parameters to final fiber diameter; most developed models are only functional for a specific polymer-solvent system. A newly simplified electrohydrodynamic model has been developed, and has identified important dimensionless groups and scaling regimes controlling the stable portion of an electrospinning jet. The present work studies a novel polymer solvent system, poly(ethylene oxide) ??? chloroform, with the aim of further testing the newly simplified model for a completely different system through the use of high speed imaging and velocimetry measurements. The poly(ethylene oxide) ??? chloroform system is unique because of the fact that a completely linear electrospinning jet without a bending instability can be produced. This allows for the collection of a large volume of highly spatially oriented fibers of uniform diameter, which is not normally possible. Experiments revealed that this linear system followed some of the scaling regimes predicted in the model...

Corn starch nanofilaments obtained by electrospinning

Ledezma-Oblea,J.G.; Morales-Sánchez,E.; Gaytán-Martínez,M.; Figueroa-Cárdenas,J.D.; Gaona-Sánchez,V.A.
Fonte: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería Publicador: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2015 EN
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Until today, there are not reports of nanofilaments from starch. Therefore, the aim of this research was to find the conditions for obtaining nanofilaments from natural polymers by the electrospinning process. An electrospinning prototype system built at laboratory was used. The performance of native corn starch water suspension (control), and succinated corn starch mixed with water, glycerol and surfactant were evaluated by electrospinning. Several processing parameters were critical for obtaining nanofilaments, among them were distance between needle and collector, voltage, conductivity, dielectric constant as well as water suspension viscosity. Native starch was not appropriate for obtaining nanofilaments due to particles agglomeration by retrogradation. To overcome those problems, several mixtures of succinated starch, surfactant Tween-20 and glycerol were evaluated. The viscosity was reduced from 664 cP in native starch mixture to 28 cP in succinated corn starch/Tween 20/glycerol, and the resulting low viscosity together with high dielectric constant >253 were adequated for achieving nanofilament of average diameter of 200 nm by electrospinning due to formation of Taylor's cone. Corn starch nanofilaments have several amazing characteristics making them optimal for many applications as scaffolds in regenerative medicine...