Adhesion and protective properties of polyvinyl alcohol nanofibrous composite fabrics

To avoid the separation of nanofiber mats and substrates during post-processing, the substrate was pretreated by plasma before electrospinning. Polyvinyl alcohol (PVA) nanofiber mats were deposited on the habutae, polyester-taffeta, and nylon-taffeta fabrics by a needless electrospinning setup with spiral disk spinnerets. The effects of plasma treatment on the adhesion of electrospun PVA nanofibrous composite fabrics were studied. The aerosol particles protective performance and wearabilities were also investigated as a function of the thickness of electrospun PVA nanofiber mat. Results showed that the surface nanoscale concave–convex roughness of substrate fabric was formed after oxygen plasma treatment. The peeling strength and peeling energy increased with the increase in surface roughness in a limited range. The peeling energy of PVA/nylon-taffeta enhanced to 2.97 times when nylon-taffeta treated by oxygen plasma at 200 W for 3 min. The aerosol particle filtration efficiency enhanced with the increase in electrospinning time, and the quality factor of PVA/nylon-taffeta was the highest with electrospinning for 10 min. Simultaneously, the air permeability and the water vapor transmission rate of PVA/nylon-taffeta decreased with the increase in electrospinning time, whereas the drape coefficient increased.     

Essential Oil Bioactive Fibrous Membranes Prepared via Coaxial Electrospinning

A novel antimicrobial composite material was prepared by encapsulating orange essential oil (OEO) in zein prolamine (ZP) via the coaxial electrospinning (ES) technique. By manipulating process parameters, the morphological features of ZP/OEO fibers were modulated. Fine fibers with diameters ranging from 0.7 to 2.3 μm were obtained by regulating ZP solution concentration and process parameters during the ES process. Optimal loading capacity (LC) and encapsulation efficiency (EE) of OEO in fibrous ZP mats were determined to be 22.28% and 53.68%, respectively, and were achieved using a 35 w/v% ZP ES solution. The encapsulation of OEO was found to be reliant on ZP solution concentration (the enveloping medium). SEM analysis indicates the surface morphology of ZP/OEO electrospun fibers is dependent on ZP solution loading volume, with lower ZP concentrations yielding defective fibrous structures (for example, beaded and spindled‐string like morphologies). Furthermore, this loading volume also influences OEO LC, EE, mat water contact angle and oil retention. CCK‐8 assay and cell morphology assessment (HEK293T cells) indicate no significant change with electrospun ZP and ZP/OEO fibrous membranes over an 8 h period. Antimicrobial activity assessment using Escherichia coli, suggests composite nonwovens possess sterilization properties; elucidating potential application in active food packaging, food preservation and therefore sustainability.     

J. Cosmet. Sci., 59, 233–242 (May/June 2008) Electrospun poly (vinyl alcohol) fiber mats as carriers for extracts from the fruit hull of mangosteen

Electrospinning is a process used to produce ultrafine fibers with diameters in the nanometer range. Electrospun fiber mats have high potentials for biomedical uses, due to their high surface area and ease of drug incorporation into the fibers. They can be used as carriers for drug delivery and can enhance drug release and skin permeability. The aim of this study was to prepare electrospun fiber mats and to incorporate extracts from the fruit hull of mangosteen. Anti-oxidant activity and extract release were determined and compared between the extract incorporated in the electrospun fiber mats and in the cast films. Poly (vinyl alcohol) (PVA) was selected as the polymer matrix. Extracts in the amount of 2.5%, 5%, and 10% w/w, based on the weight of PVA, were incorporated with 10% w/w PVA to finally obtain electrospun fiber mats and cast films. The extract content was evaluated by anti-oxidative activity using the 2,2-diphenyl-1picryhydrazyl (DPPH) method. The morphology of the electrospun fiber mats was analyzed using a scanning electron microscope (SEM). The results showed that the diameters of the fibers were in nanoscales and that no crystal of the extract was found at any concentration of the extract. The extract contents in the electrospun fiber mats prepared at 2.5%, 5%, and 10% w/w of the extract were 9.6%, 9.7%, and 10.8% of the initial loading concentration, respectively, whereas, those in the cast films were 23.9%, 14.5%, and 21.0%, respectively. The release of the extract from the electrospun fiber mats prepared at 2.5%, 5%, and 10% w/w of the extract at 120 min were 73.2%, 83.6%, and 81.3% w/w, respectively. However, much slower release from the cast films was observed (i.e. 4.3%, 29.1%, and 40.8% w/w, respectively).     

可见光响应聚丙烯腈纤维膜的制备及其光催化性能

通过静电纺丝及后续的水热处理工艺制备载有二氧化钛的聚丙烯腈纤维膜,该纤维膜具有可见光响应光催化性能。静电纺丝得到的初生纤维中含有钛酸四丁酯、硝酸钆、聚丙烯腈和聚乙烯吡咯烷酮,纤维表面光滑(直径约为320 nm)。再将初生纤维膜置于特氟龙水热釜中进行水热处理;纤维变成表面凹凸不平的多孔纤维(直径约为350 nm,BET比表面积为17.45 m2/g);结合XPS和XRD测试结果证实载有anatase相二氧化钛(Gd/N-Ti O2)晶体的聚丙烯腈纤维膜制备成功。在室温条件下,这种有机/无机杂化纤维膜对罗丹明B水溶液具有明显的可见光降解效果。     

Electrospinning and characterization of poly (vinyl alcohol)–sericin nanofibers as a potential for tissue engineering applications

Poly vinyl alcohol (PVA) is a hydrophilic, biocompatible, and biodegradable polymer which has found application in biodrugs and tissue engineering. Sericin accompanying silk is a waste which is produced in scouring silk and has interesting properties which has attracted the attention of researchers. Silk sericin is also hydrophilic, biodegradable, and biocompatible. Moreover, it is cheap and anti-cancerous. Mixture of PVA and sericin in the form of 2D membrane or 3D hydrogels has been employed to heal skin damages. This research aimed at electrospinning PVA–sericin blend nanofibers in the form of a mat which has applications in tissue engineering, using dimethyl sulfoxide (DMSO) as an organic solvent. This research showed that the solution of PVA–sericin in DMSO was electrospinnable; however, the addition of urea to the solution made the electrospinning easier. The electrospinning solution contained ratio of 0:100, 10:90, 15:85, 20:80, and 25:75 sericin (%w/w)–PVA (%w/w). The electrospun PVA–sericin nanofibers had an average diameter in the range of 179–285 nm. X-ray diffractometer and differential scanning calorimetry investigations showed no reaction occurring between PVA and sericin. Polyvinyl alcohol 100% was also electrospun in DMSO. Up to now, the electrospinning of PVA in non-aqueous media has not been reported in the literature.     

静电纺丝法制备锂离子电池隔膜的研究进展

利用静电纺丝技术可以制得高比表面积、高孔隙率的纤维及纤维毡状材料,使其在制备锂离子电池隔膜中具有明显的应用优势。综述了采用静电纺丝法制备纳米纤维膜用作电池隔膜的技术特点及其主要影响因素。重点阐述了静电纺隔膜的结构和性能,如膜的形态结构、机械性能、化学稳定性和热稳定性等。     

Electrospinning of Poly(vinyl alcohol) Nanofibers Loaded with Hexadecane Nanodroplets

Abstract: The feasibility of producing poly(vinyl alcohol) (PVA) nanofibers containing fine-disperse hexadecane droplets by electrospinning a blend of hexadecane-in-water emulsions and PVA was investigated. Hexadecane oil-in-water nanoemulsions (d₁₀= 181.2 ± 0.1 nm) were mixed with PVA at pH 4.5 to yield polymer-emulsion blends containing 0.5 to 1.5 wt% oil droplets and 8-wt% PVA. The solution properties of emulsions and emulsion-PVA blends (viscosity, conductivity, surface tension) were determined. Solutions were electrospun and the morphology and thermal properties of deposited fiber mats characterized by scanning electron microscopy and differential scanning calorimetry. Fiber mats were dissolved in buffer to liberate incorporated hexadecane droplets and the buffer solutions analyzed by optical microscopy, UV-spectroscopy, and light scattering. Analysis of dry fiber mats and their solutions showed that emulsion droplets were indeed part of the electrospun fiber structures. Depending on the concentration of hexadecane in the initial emulsion-polymer blends, droplets were dispersed in the fibers as individual droplets or in form of aggregated flocs of hexadecane droplets. Nanofibers with spindle-like perturbations or nanofibers containing bead-like structures with approximately 5 times larger than the size of droplets in the original nanoemulsion were obtained. Remarkably, incorporation of hexadecane droplets in fibers did not alter size of individual droplets, that is, no coalescence occurred. The manufacture of solid matrix containing nanodroplets could be of substantial interest for manufacturers wishing to develop encapsulation system for lipophilic functional compounds such as lipid-soluble flavors, antimicrobials, antioxidants, and bioactives with tailored release kinetics. Practical Applications: The paper describes the formation of electrospun nanofibers from hydrophilic polymers that contain fine-disperse emulsion droplets. By incorporating emulsion droplets, a large variety of lipophilic ingredients can be easily loaded into the fibers’ hydrophilic polymer matrix. This is of practical importance as to date the only way to include a lipophilic ingredient in a nanofibers is by dissolving the lipophilic ingredient and polymer in an organic solvent followed by electrospinning. However, use of an organic solvent is (a) not feasible if one wants to electrospin hydrophilic polymers, and (b) use of organic solvents is generally highly undesirable in the food industry. Our results should be of interest to a number of industries such as the food, pharmaceutical, chemical, and personal care industries that are generally in need of novel matrices that can serve as carrier vehicles and release functional components such as flavors, antimicrobials, antioxidants, drugs, and bioactives.     

静电纺聚乳酸纤维毡的微观结构及力学行为

通过静电纺丝可以制备由直径为数微米的聚乳酸纤维构成的多孔状材料。在确定纺丝工艺条件的基础上,分析接收基底对PLA纤维毡微观结构和力学性能的影响。研究结果表明:质量分数为11%的聚乳酸/二氯甲烷溶液可以利用静电纺纺出连续光滑且比较均匀的纤维;当以纳米级的静电纺丝素或锦纶纤维毡为基底时,可以使PLA纤维的分布均匀化,同时纤维的直径下降;经过复合后,PLA复合纤维毡承受负荷的能力得到了很大提高。     

Preferences of dairy cows for three stall surface materials with small amounts of bedding

Farmers’ concerns about the economy, cost of labor, and hygiene have resulted in reduced use of organic bedding in stalls for dairy cows; however, the reduced use of organic bedding possibly impairs cow comfort. The effects of different stall surface materials were evaluated in an unheated building in which only a small amount of bedding was used. The lying time and preferences of 18 cows using 3 stall surface materials (concrete, soft rubber mat, and sand) were compared. All materials were lightly bedded with a small amount of straw, and the amount of straw added to each stall was measured. The cows only had access to stalls of one surface type while their lying time was observed. Lying times were longest on the rubber mats compared with other surfaces (rubber mat 768; concrete 727; sand 707 ± 16 min/d). In a preference test, cows had access to 2 of the 3 types of stalls for 10 d and their stall preference was measured. Cows preferred stalls with rubber mats to stalls with a concrete floor (median 73 vs. 18 from a total of 160 observations per day; interquartile range was 27 and 12, respectively), but showed no preference for sand stalls compared with stalls with a concrete floor or with rubber mats. More straw was needed on sand stalls compared with concrete or mat (638 ± 13 g/d on sand, 468 ± 10 g/d on concrete, and 464 ± 8 g/d on rubber mats). Lying times on bedded mats indicated that mats were comfortable for the cows. If availability or cost of bedding material requires limiting the amount of bedding used, rubber mats may help maintain cow comfort.     

PVDF静电纺纤维毡表面电性能

研究静电纺丝过程中纺丝液的质量浓度和性质、施加电压的极性和施加方式对所得聚偏二氟乙烯（PVDF）超细纤维微观形貌、纤维直径和纤维毡表面电性能的影响,并考察采用静电纺丝方法制备PVDF驻极体的可行性。结果表明：静电纺丝所得PVDF纤维毡表面有一定量的电荷残留,其电荷残留量与纺丝原液质量浓度成正比,但残留电荷很快耗散,不能直接用来制备驻极体;对比发现不同介电常数的接收介质（如：锡箔,非织造布,塑料薄膜等）对静电纺丝纤维毡表面电势残留有直接的影响。     

Effect of electrospinning parameters on piezoelectric properties of electrospun PVDF nanofibrous mats under cyclic compression

The high piezoelectric response capacity of electrospun PVDF nanofibers is currently a challenging area of research, and this study attempts to optimize the piezoelectric properties of electrospun PVDF nanofibrous mat under controlled electrospinning process. Some experiments were designed to study the relationship between electrospinning processing parameters and the piezoelectric properties of PVDF mats under cyclic compression, and this relationship was compared with the change of crystalline structure features with the electrospinning parameters. The excitation method is based on low velocity compression test by cyclically pressing flat contactor on samples. The impact of each of processing parameters has been investigated. It was found that three electrospinning parameters including: applied voltage, feeding volume flow rate and syringe needle tip diameter, are significant influential factors to the piezoelectric properties of the electrospun PVDF nanofibrous mats. However, the feeding volume flow rate has a greater effect on the piezoelectric responses to cyclic compression than both applied voltage and volume flow rate does, and its effect on the piezoelectric responses is different from that of β-phase fraction of crystalline structure within PVDF nanofiber. It was also observed that the relationship between the piezoelectric peak intensity and the applied voltage as well as the feeding volume flow rate is nonlinear.     

Untersuchungen zur Permeabilität von Faser-, Span- und OSB-Matten für Gase

After an explanation of the importance of mat permeability during wood-based panel manufacture the relevant literature is reviewed. Preparation of specimens and gas-permeability measurement methods are described. Darcy’s law can be applied to describe the gas flow in wood-based panel mats under the influence of a pressure gradient during the hot pressing process. The permeability parallel to the panel surface influences the rate of venting. The transverse permeability is important for the convective transfer of heat and moisture into the core layer. The permeability of fibre, particle and strand mats with densities varying from 200 to 1200 kg/m³ was determined. At lower densities, the parallel and transverse permeability of fibre mats and the transverse permeability of OSB mats are distinctly lower than the permeability of particle mats. Particle mats made from surface material are less permeable than those made from core material. At higher densities, fibre mats reveal highest permeability followed by surface and core layer particle mats and strand material. At higher densities, mat permeability decreases with increasing glue and moisture contents. The pressing temperature and the accompanying plastizisation of the mats does not influence the permeability.     

聚酰胺含量对静电纺丝素纤维结构和性能的影响

将质量分数分别为9%和12%的再生丝素甲酸溶液和聚酰胺6/66共聚物的甲酸溶液混合,在喷丝头到接收屏之间的距离(C-SD)为15 cm、电压为15 kV的条件下进行静电纺丝得到丝素/聚酰胺复合纤维。研究了聚酰胺的含量和纤维直径、结晶结构以及纤维毡的力学性能之间的关系,探讨了产品在乙醇处理后结构和性能的变化。研究发现,聚酰胺的加入不仅可以降低纤维直径,而且提高了纤维的结晶度和纤维毡的断裂强度;乙醇处理后纤维发生均匀溶胀,结晶度提高,纤维毡的断裂强度和在水中的尺寸稳定性增加。     

Influence of solution and processing parameters towards the fabrication of electrospun zein fibers with sub-micron diameter

The effects of processing and solution parameters on the morphology of food grade electrospun fibers were investigated. The relationship of entanglement concentration (C_e) of zein solution and its electrospinnability was inspected to determine the correlation of fiber morphology with the rheology of solutions. Bead-free and uniform zein electrospun fibers were successfully constructed. Response surface methodology (RSM) was utilized to facilitate a more systematic understanding of the electrospinning parameters of zein solutions. The electrospinning parameters studied were concentration of zein solution, solution feed rate, applied voltage and distance between needle tip and collector. The individual and interaction effects between the parameters on average diameter of the electrospun fibers were determined using Box and Behnken factorial design. The interaction effect between feed rate and voltage, the quadratic coefficients of the applied voltage as well as linear coefficients of the solution concentration, voltage and feed rate were found statistically significant in the fabrication of sub-micron fibers. Hence, this work provides an overview on the impact of solution and processing parameters to the fabrication of zein electrospun fibers which may find uses as nanostructured materials in food industry.     

静电纺蛋白质和多糖纳米纤维及其在食品行业的应用进展

静电纺丝技术是一种简单且有效地制备纳米纤维的方法,所得纳米纤维具有纤维直径可控、孔隙率高及比表面积大等优良特性,在生物医学、过滤材料、传感器、酶固定化及食品包装等领域具有良好的应用前景。应用于食品行业的电纺纳米纤维必须生物相容性好、毒性低且可生物降解,故目前常采用蛋白质和多糖等天然聚合物进行静电纺丝。本文主要综述了含蛋白质(大豆分离蛋白、玉米醇溶蛋白、乳清蛋白等)或多糖(壳聚糖、透明质酸、淀粉、普鲁兰多糖等)电纺纳米纤维的制备过程、电纺过程中各主要因素对纤维形貌的影响,所得纳米纤维的特性及其在食品行业,包括抗菌保鲜、抗氧化和控制释放等方面的潜在应用,并展望了静电纺蛋白质和多糖纳米纤维未来的研究方向。     

Properties of electrospun PVA/nanoclay composites

Laponite^® nanoclay was added to poly(vinyl alcohol) (PVA) solution which was electrospun to make PVA/Laponite^® nanocomposites. After adding Laponite^® nanoclay, fibers were observed to be warped, making their surface rougher. The addition of Laponite^® resulted in less water solubility of electrospun PVA web. PVA/Laponite^® nanocomposite disintegrated after exposure to heat and agitation in water reducing its filtration capability. PVA/Laponite^® nanocomposites showed lower air permeability than electrospun PVA webs probably because of more resistance to air stream caused by rougher and less uniform fiber surface. Tensile and tear strength were weakened by Laponite^® nanoclay due to several reasons: random orientation of nanoclay along fiber axial direction, and fiber discontinuity caused by nanoclay and inhomogeneous distribution of nanoclay.     

Culture systems for pluripotent stem cells

Pluripotent stem cells have the capacity to self renew and to differentiate to cells of the three somatic germ layers that comprise an organism. Embryonic stem cells are the most studied pluripotent stem cells. Pluripotent stem cells have also been derived from adult tissues. Both embryonic and adult stem cells represent valuable sources of cells for applications in cell therapy, drug screening and tissue engineering. While expanding stem cells in culture, it is critical to maintain their self-renewal and differentiation capacity. In generating particular cell types for specific applications, it is important to direct their differentiation to the desired lineage. Challenges in expansion of undifferentiated stem cells for clinical applications include the removal of feeder layers and non-defined components in the culture medium. Our limited basic knowledge on the requirements for maintaining pluripotency of adult pluripotent stem cells and the lack of appropriate markers associated with pluripotency hinders the progress toward their wide spread application. In vitro differentiation of stem cells usually produces a mixed population of different cell lineages with the desired cell type present only at a small proportion. Use of growth factors that promote differentiation, expansion or survival of specific cell types is key in controlling the differentiation towards specific cell lineages. A variety of bioreactors for cell cultivation exist and can be readily adapted for stem cell cultivation and differentiation. They provide a well-controlled environment for studying the process of stem cell propagation and differentiation. Their wide use will facilitate the development of processes for stem cell application.     

静电纺MWNTs/丝素复合纳米纤维毡的结构与性能

静电纺丝素纤维毡在水中极不稳定,力学性能较差,这些缺陷限制了其应用。将经过酸处理的多壁碳纳米管（MWNTs）均匀地分散在丝素膜甲酸溶液中,以MWNTs增强静电纺丝素纳米纤维,XPS的测定结果显示,碳纳米管并不是仅仅以物理形式混杂在丝素纤维中,而是形成了某些有助于提高增强效果的化学键。随碳纳米管质量分数的增加,纤维直径明显下降,纤维内部结构的规整性有所提高。当纺丝液中MWNTs的质量分数小于1%时,复合纤维毡的断裂强度和初始模量都有明显的增强,但是MWNTs的质量分数太大时,力学性能反而恶化。     

纳米TiO2对魔芋葡甘聚糖/玉米醇溶蛋白复合膜结构和性能的影响

本文以魔芋葡甘聚糖、玉米醇溶蛋白为成膜基质,添加不同含量（1%、2%、3%）的纳米TiO₂,以流延方式制备纳米TiO₂/魔芋葡甘聚糖/玉米醇溶蛋白复合膜,并对复合膜的微观结构、热性能、力学性能、疏水性、水蒸气透过率和抑菌性能进行了分析。结果表明,纳米TiO₂与魔芋葡甘聚糖、玉米醇溶蛋白间发生相互作用,有良好的相容性;添加纳米TiO₂使复合膜表面粗糙度增加,复合膜热稳定性和疏水性增强,力学性能降低;纳米TiO₂添加量为1% wt时,复合膜的水蒸气透过率（5.7×10?13 g·cm/（cm2·s·Pa））和溶胀率（16.4%）最小,水接触角值（99.6 °）最大;复合膜对金黄色葡萄球菌和大肠杆菌有明显的抑制作用,对枯草芽孢杆菌的抑制作用不明显。本研究为纳米TiO₂/魔芋葡甘聚糖/玉米醇溶蛋白复合膜作为包装材料的开发与应用提供一定参考依据。     

Wettability, surface microstructure and mechanical properties of films based on phosphorus oxychloride-treated zein

BACKGROUND: Zein, the predominant protein in corn, has been extensively studied as an alternative packaging material in edible and biodegradable films. However, films made from 100% zein are brittle under normal conditions. The aim of this investigation was to improve the film‐forming properties of zein by chemical phosphorylation. The surface hydrophobicity, surface microstructure and mechanical properties of films based on untreated and phosphorus oxychloride (POCl₃)‐treated zein were evaluated and compared. The effect of POCl₃ treatment on the rheological properties of zein solutions was also studied. RESULTS: POCl₃ treatment, especially at pH 7 and 9, led to an increase in the apparent viscosity of zein solutions. Atomic force microscopy (AFM) analysis showed that the film based on POCl₃‐treated zein at pH 7 had a stone‐like surface microstructure with a higher roughness (R_q) than the untreated zein film. The AFM data may partially account for the phenomenon that this film exhibited high surface hydrophobicity (H₀). POCl₃ treatment diminished the tensile strength (TS) of zein films from 4.83–6.67 to 1.3–2.29 MPa. However, the elongation at break (EAB) of the films at pH 7 and 9 increased from 3.0–4.5% (control film) to 150.1–122.7% (POCl₃‐treated film), indicating the potential application of zein films in wrapping foods or in non‐food industries such as sugar, fruit or troche that need good extension packing materials. CONCLUSION: The data presented suggest that the properties of zein films could be modulated by chemical phosphorylation treatment with POCl₃ at an appropriate pH value. Copyright © 2011 Society of Chemical Industry