维生素对聚乙烯醇溶液静电纺丝性能的影响

将维生素(VC)溶解在质量分数8%的聚乙烯醇(PVA)水溶液中,通过静电纺丝制得PVA/VC共混纳米纤维。分析了VC含量对溶液性能及静电纺丝速度的影响;测试了纤维的形貌结构及力学性能。结果表明:PVA/VC共混溶液属于切力变稀流体;当PVA/VC质量比为100/10或100/20时,共混溶液的电导率和静电纺丝速度较纯PVA溶液明显提高,制得的纳米纤维表面光滑,粗细均匀;与纯PVA纳米纤维比较,其平均直径和拉伸强度降低,断裂伸长率提高。     

聚乙烯醇/壳聚糖共混纤维毡的制备与表征

将不同质量比的聚乙烯醇(PVA)和壳聚糖(CS)溶于甲酸中配制成共混溶液进行静电纺丝,得到PVA/CS共混纤维毡。对纤维毡进行原子力显微镜(AFM)表征、红外光谱分析和吸水性能测试。结果表明:共混溶液中PVA质量分数为8%,CS质量分数为4%时,静电纺丝效果较好,纤维光滑平直,平均直径为307 nm,;红外光谱分析表明,PVA和CS共混时,大分子之间产生了较强的氢键作用,CS原有的结晶结构在一定程度上被破坏;PVA/CS共混纤维毡的吸水量和吸水速率都小于PVA纤维毡。     

稀乙酸对聚乙烯醇水溶液静电纺丝性能的影响

采用质量分数3%乙酸水溶液作为高醇解度聚乙烯醇(PVA)的溶剂,研究了PVA稀乙酸溶液的性质及其静电纺丝工艺。结果表明:加入质量分数3%乙酸,PVA溶液粘度下降,表面张力及电导率提高;纺丝液浓度对PVA稀乙酸溶液的静电纺丝性能影响最大;当PVA稀乙酸溶液质量分数为8%～13%,固化距离15mm,纺丝电压14～18kV时,可制得形态良好的PVA超细纤维无纺毡。     

静电纺抗紫外PVA/芦丁纳米纤维膜的制备及其性能研究

以聚乙烯醇(PVA)为原料,以芦丁为改性剂,将PVA与芦丁共混于去离子水中,通过静电纺丝制备抗紫外PVA/芦丁纳米纤维膜,并对其性能进行表征。结果表明:静电纺丝工艺条件为电压20 k V,纺丝速度0.5 m L/h,接收距离10 cm,温度30℃;加入少量芦丁,对PVA静电纺丝成纤性无影响,但纤维直径增大,直径均匀性变差;纤维中PVA与芦丁之间存在氢键;相对PVA,芦丁质量分数为4.76%时,PVA/芦丁纳米纤维膜的纤维平均直径为302 nm,抗紫外系数大于40,具有良好的抗紫外性能。     

聚乳酸/聚乙烯醇纳米纤维的制备及结构

以二甲基亚砜为溶剂,制备不同配比的聚乳酸(PLLA)和聚乙烯醇(PVA)的混合溶液,静电纺丝制得PLLA/PVA纳米纤维。采用红外光谱仪、原子力显微镜等对PLLA/PVA纳米纤维结构与性能进行了表征。结果表明:PLLA/PVA纳米纤维中PVA上的羟基与PLLA上的羰基形成了氢键,PLLA与PVA之间存在一定的相互作用,但PLLA/PVA纳米纤维存在相分离现象;混合溶液的PLLA质量分数为11%,PVA质量分数为8%时可以得到较好的PLLA/PVA纳米纤维,但PVA质量分数为6%时出现液滴及珠丝,PVA质量分数为4%时,不能制得纳米纤维。     

丝素蛋白/海藻酸钠复合纤维的制备与性能表征

为了提高海藻酸钠(SA)纤维的力学性能,将从蚕茧中提取的丝素蛋白(SF)和SA共混,制备了SF/SA纺丝溶液,通过湿法纺丝制得SF/SA复合纤维,对纺丝溶液流变性能进行了研究,对SF/SA复合纤维进行了结构与性能表征。结果表明:SF/SA纺丝溶液为切力变稀的假塑性流体,纺丝溶液的表观黏度随SF含量增加呈增加的趋势,当SF质量分数(相对SA)为10%时,纺丝溶液结构黏度指数最小,可纺性最好;提取的SF以无规卷曲结构和β-折叠结构为主,SA和SF间有较强的氢键作用;SF/SA复合纤维以非晶形态存在,纤维表面存在明显的沟槽结构,与纯SA纤维相比,SF的加入提高了SA纤维的力学性能,SF质量分数为10%的SF/SA复合纤维的断裂强度高达1.63 cN/dtex,较SA的提高了22.5%,SF的加入使复合纤维的耐热性略有降低。     

PVP/PEO复合微纳米纤维的电纺性研究

采用聚乙烯毗咯烷酮/聚氧化乙烯/水(PVP/PEO/H2O)体系进行静电纺丝制备PVP/PEO复合微纳米纤维,研究了PVP/PEO共混溶液浓度、PVP相对分子质量及PVP:PE0(质量比)对PVP静电纺丝的影响.结果表明:当溶液质量分数增大到15%、PVP相对分子质量为1.3×106或PEO含量增大时,均可制得形貌清晰、表面光滑的微纳米纤维.当PVP/PEO溶液质量分数为12%、PVP相对分子质量为1.3 × 106及PVP:PE0(质量比)为8:2时,静电纺丝所得纤维形貌最佳.     

PEDOT/PSS质量分数对纺丝液流变性能及导电纤维可纺性的影响

将质量分数为10%的聚乙烯醇(PVA)水溶液与聚3,4-乙烯二氧噻吩/聚苯乙烯磺酸(PEDOT/PSS)水分散液共混,经过恒温高速搅拌,制备出均匀的PVA/PEDOT/PSS共混纺丝液,随后通过湿法纺丝制备出PVA/PEDOT/PSS纤维。借助旋转式流变仪探究不同PEDOT/PSS质量分数的纺丝液在纺丝温度的差异下,纺丝液的流变特性与可纺性的关系。采用高阻计和电子单纤维强力仪对成品纤维的导电性能和力学性能进行测试表征。使用扫描电子显微镜对不同PEDOT/PSS质量分数的纤维表面形貌进行表征。结果表明,PEDOT/PSS质量分数在0%～9.09%的质量分数范围内,随着纺丝液中PEDOT/PSS质量分数的增加,纺丝液黏度增大,PVA/PEDOT/PSS纺丝液可纺性呈先提高后降低的趋势。在30～90℃的范围内,随着纺丝体系温度的提高,PVA/PEDOT/PSS纺丝液可纺性呈先升高后降低的趋势;随着PEDOT/PSS质量分数的提高,PVA/PEDOT/PSS纤维的电导率逐渐升高,拉伸强度逐渐增加,拉伸断裂伸长率逐渐降低。     

小麦蛋白/聚乙烯醇复合纳米纤维的制备及其表征

以小麦蛋白、聚乙烯醇(PVA)为原料,采用静电纺丝法制备小麦蛋白/PVA共混复合纳米纤维,重点研究纺丝液质量分数、电压、接收距离对纤维形态的影响,利用扫描电镜、傅里叶变换红外光谱、X-射线衍射光谱对纤维的形态与结构进行表征。结果表明:在纺丝液质量分数10%、小麦蛋白与PVA质量比8∶2、电压12 kV、接收距离10 cm的条件下,可以制备平均直径为280 nm左右的均一、表面光滑的纳米纤维。小麦蛋白与PVA复合后,分子间以氢键结合。     

丝素蛋白-聚乙烯醇共混改性电纺膜的制备

采用静电纺丝技术,以特殊设计的金属丝螺旋盘绕滚筒作为接收装置,制备了具有一定取向的丝素蛋白(SF)-聚乙烯醇(PVA)共混纳米纤维材料。利用扫描电子显微镜(SEM)对纤维形貌进行观察,并通过Image-Pro Plus软件对纤维细度进行测试,探讨了SF与PVA的配比以及纺丝电压、接收距离等静电纺丝参数对所得纳米纤维形貌、细度及其分布的影响。结果表明:将质量浓度为25 kg/L的SF与质量分数为8%的PVA以质量比15∶3.2共混,并采用20 kV的纺丝电压和13 cm的接收距离静电纺时,所得纳米纤维的平均直径约为238 nm,且直径分布较为均匀。采用该法制得的纳米纤维材料具有一定的纤维取向,有利于细胞生长,可应用于生物医药领域。     

Preparation of atactic poly(vinyl alcohol)/sodium alginate blend nanowebs by electrospinning

Through the blending of a rigid polymer, sodium alginate (SA), and a flexible polymer, atactic poly(vinyl alcohol) (PVA), with various ratios of SA and PVA and through the electrospinning of SA/PVA solutions, SA/PVA blend nanowebs were successfully prepared. The structure and morphology of the SA/PVA blend nanowebs were investigated through a series of instrumental analyses. Through the examination of the morphological variations of each blend web, it was found that with only PVA, the electrospun nanowebs had very uniform and fine fiber structures, but the SA/PVA blend nanowebs had a mixture of large beads and fibers, which were generated with increasing SA content. A thermal analysis indicated that the endothermic peaks of the SA/PVA blend nanowebs decreased with an increase in the SA content. The SA content was determined by the observation of the changes in the SA peak intensity via Fourier transform infrared spectroscopy. The tensile strength decreased with increasing SA content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Controlled mechanical and swelling properties of poly(vinyl alcohol)/sodium alginate blend hydrogels prepared by freeze–thaw followed by Ca2+ crosslinking

Poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend hydrogels have immense potential for use as functional biomaterials. Understanding of influences of processing parameters and compositions on mechanical and swelling properties of PVA/SA blend hydrogels is very important. In this work, PVA/SA blend hydrogels with different SA contents were prepared by applying freeze–thaw method first to induce physical crosslinking of PVA chains and then followed by Ca²⁺ crosslinking SA chains to form interpenetrating networks of PVA and SA. The effects of number of freeze–thaw cycles, SA content and Ca²⁺ concentration on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels were investigated. The results showed that the blend hydrogels have porous sponge structure. Gel fraction, which is related to crosslink density of the blend hydrogels, increased with the increase of freeze–thaw cycles and strongly depended on SA content. The SA content exerts a significant effect on mechanical properties, swelling kinetics, and pH‐sensitivity of the blend hydrogels. The number of freeze–thaw cycles has marked impact on mechanical properties, but no obvious effect on the pH‐sensitivity of the PVA/SA blend hydrogels. Concentration of CaCl₂ aqueous solution also influences mechanical properties and pH‐sensitivity of the blend hydrogel. By altering composition and processing parameters such as freeze–thaw cycles and concentration of CaCl₂ aqueous solution, the mechanical properties and pH‐sensitivity of PVA/SA blend hydrogels can be tightly controlled. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characteristics of the nanofiltration composite membranes based on PVA and sodium alginate

Chemically stable nanofiltration (NF) composite membranes based on poly(vinyl alcohol) (PVA) and sodium alginate (SA) (hereafter, these membranes are called PVA/SA composite membranes) were prepared by coating microporous polysulfone (PSF) supports with dilute PVA/SA blend solutions. The PSF supports were pretreated with small monomeric compounds to reduce their pore size and to improve their hydrophilicity before coating with the PVA/SA blend solutions. The concentration of the PVA/SA blend solutions ranged from 0.1 to 0.3 wt %. The membranes prepared in this study were characterized with various methods such as SEM, FTIR, permeation tests, and z‐potential measurements. Especially, chemical stabilities of the membranes were tested, using three aqueous solutions with different pHs such as a HCl solution (pH 1), a K₂CO₃ solution (pH 12.5), and a NaOH solution (pH 13). Their chemical stabilities were compared with that of a polyamide (PA) composite membrane prepared from piperazine (PIP) and trimesoyl chloride (TMC). In this study, it was found that the PVA/SA composite membranes prepared showed not only good chemical stabilities but also good permeation performances in the range from pH 1 to 13. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2471–2479, 2001     

丝素-聚乙烯醇共混溶液静电纺丝及其含银纳米纤维形态研究

研究了不同丝素-聚乙烯醇（SF-PVA）配比的共混溶液和加入硝酸银的丝素-聚乙烯醇（SF-PVA）共混溶液的静电纺丝,利用扫描电镜观察纤维的形态变化。结果表明：在丝素（SF）或聚乙烯醇（PVA）占绝大部分时,整个体系溶解性保持相对稳定,容易形成比较均一的溶液,且纺丝后纤维形态比较均匀、规则;而在两组分含量接近时整个体系的溶解性能较差,不易形成比较均一的溶液,表现为溶液粘度的显著增大,纺丝后纤维不均匀、不规则。笔者选用SF/PVA=1：9（质量比）的共混纺丝液加入硝酸银,随着硝酸银在溶液中含量的增加,溶液电导率会明显增加,纤维的直径明显下降;但随着电导率的增大,纤维中珠状物会增多,纤维均一性也变差。     

冷冻处理对α-PVA/s-PVA共混溶液静电纺丝的影响

将少量的间规聚乙烯醇(s-PVA)加入无规聚乙烯醇(α-PVA)的水溶液中,制得α-PVA/s-PVA共混溶液,对溶液进行冷冻处理,通过高压静电纺丝获得a-PVA/s-PVA纳米纤维毡.研究了s-PVA的加入及冷冻处理对PVA溶液静电纺丝性能的影响.结果表明:随着s-PVA含量的增加,共混溶液的剪切枯度升高,静电纺纤维毡的平均直径减小,拉伸强度增加;冷冻处理后的共混溶液静电纺丝制得的纳米纤维毡与未经冷冻处理的相比,其平均直径增大,珠结减小,拉伸强度提高了约8倍.     

Preparation and characterization of PVA/SA composite nanofiltration membranes

Nanofiltration (NF) composite membranes based on poly(vinyl alcohol) (PVA) and sodium alginate (SA) were prepared by coating PVA/SA (95/5 in wt %) mixture solutions on microporous polysulfone (PSF) supports. For the formation of a defect free thin active layer on a support, the PSF support was multi‐coated with a dilute PVA/SA blend solution. The PVA/SA active layer formed was crosslinked at room temperature by using an acetone solution containing glutaraldehyde as a crosslinking agent. The prepared composite membranes were characterized with a scanning electron microscopy (SEM), a Fourier transform infrared spectroscopy (FTIR), an electrokinetic analyzer (EKA) and permeation tests: The thicknesses of the active layers were about 0.25 μm and 0.01 μm depending on the preparation conditions. The crosslinking reaction of the active layers were completed in less than three minutes via the formation of acetal linkage. The surface of the PVA/SA composite membrane was found to be anionic. The permeation properties of the composite membrane were as follows: 1.3 m³/m² day of flux and > 95% of rejection at 200 psi for 1000 ppm PEG600 solution. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 347–354, 2000     

Effect of poly(ethylene oxide) with different molecular weights on the electrospinnability of sodium alginate

Although sodium alginate (SA) could not be electrospun from its aqueous solution, SA-based electrospun nanofibers can be fabricated with the help of polyethylene oxide (PEO). In this study, the influence of PEO on the electrospinnability of SA aqueous solution was investigated and the roles of chain entanglements and conformations of the blend system were emphasized. It was found that a little amount of PEO100 with high molecular weight could improve the electrospinnability of SA aqueous solution. However, a large amount of PEO2 with low molecular weight had no positive effect on the electrospinnability of SA aqueous solution. Dynamic laser light scattering (DLLS) results showed that only when the PEO molecular chains in aqueous solution were in an entangled state, PEO can enhance the electrospinnability of SA aqueous solution. The further study on rheological measurements showed that SA molecular chains could not form significant entanglements for the electrospinning even when the SA solution concentration approached concentrated regime. SA molecular chains are closely “overlapped” due to its rigid and extended conformation and cannot form effective chain entanglement. The main contribution of PEO100 to improve SA electrospinnability is offering entanglement sites and thereby enhancing the applicable entanglement degree of the blend system. Whereas, although the chain interaction between PEO2 and SA may improve slightly the flexibility of SA chains, the significant chain entanglements of the blend solution is not achieved. Three molecular models are proposed to depict visually the effect of PEO with different molecular weights on chain conformations and entanglements of SA.     

海藻酸钠的疏水改性对其电纺性能的影响

以聚乙烯醇(PVA)作为助纺剂,对疏水改性的海藻酸钠衍生物海藻酸辛酰胺(ACA)进行电纺性能研究。采用透射电镜、激光粒度和zeta电位分析仪、表面张力仪、电导率仪和流变仪对ACA的胶体界面性能进行表征,并采用扫描电镜、红外光谱仪和多晶X射线衍射仪对ACA/PVA电纺纳米纤维膜的形貌、官能团和晶型结构进行测试。结果表明:疏水改性使海藻酸钠(SA)分子灵活性增强,ACA分子可以蜷曲形成水动力学粒径大小为324 nm(PDI=0.38),zeta电位为-43.8 m V的胶束。疏水改性和添加PVA助纺剂可以有效地降低SA溶液的表面张力和电导率,使其有效链缠结增多,ACA/PVA电纺纳米纤维膜的形貌更加规整均一。光谱分析结果表明,ACA和PVA两者间的氢键作用力是其增加链缠结点,实现静电纺丝的主要作用力。     

Tailoring Unidirectional Water-Penetration Janus Fabric with Surface Electrospun Deposition

This paper provides a new method to fabricate an integrated Janus fabric that has excellent unidirectional water-penetration property. Based on commercial polyester fabric that is pretreated with CaCl₂ solution, polyvinyl alcohol/sodium alginate (PVA/SA) solution is deposited directly on the fabric via electrospinning and in situ chelated with Ca²⁺ contained in the fabric. The in situ formed PVA/SA gel coating not only transfers the surface of polyester fabric from hydrophobic to hydrophilic but also retains original porous structure of polyester fabric. As the water droplet contacts with unelectrospun side of modified polyester fabric (M-PET) pretreated with 10 wt% CaCl₂, it penetrates through the M-PET within 1 s from unelectrospun side to electrospun side after application, and disappears on unelectrospun side within 2 s, and in turn, droplet spreads out on electrospun side of M-PET within 2 s after application and no penetration occurs. The M-PET pretreated with CaCl₂ solution has outstanding antistatic property, vapor, and air permeability. The impact of ratio (v/v) of the PVA and SA solution and the concentration of CaCl₂ pretreating solution on properties of the M-PET are investigated.     

Characterization of sodium alginate and poly(vinyl alcohol) blend membranes in pervaporation separation

By blending a rigid polymer, sodium alginate (SA), and a flexible polymer, poly(vinyl alcohol) (PVA), SA/PVA blend membranes were prepared for the pervaporation separation of ethanol–water mixtures. The rigid SA membrane showed a serious decline in flux and a increase in separation factor due to the relaxation of polymeric chains, whereas the flexible PVA membrane kept consistent membrane performance during pervaporation. Compared with the nascent SA membrane, all of the blend membranes prepared could have an enhanced membrane mobility by which the relaxation during pervaporation operation could be reduced. From the pervaporation separation of the ethanol–water mixtures along with the temperature range of 50–80°C, the effects of operating temperature and PVA content in membrane were investigated on membrane performance, as well as the extent of the relaxation. The morphology of the blend membrane was observed with PVA content by a scanning electron microscopy. The relaxational phenomena during pervaporation were also elucidated through an analysis on experimental data of membrane performance measured by repeating the operation in the given temperature range. SA/PVA blend membrane with 10 wt % of PVA content was crosslinked with glutaraldehyde to enhance membrane stability in water, and the result of pervaporation separation of an ethanol–water mixture through the membrane was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:949–959, 1998