静电纺丝:聚丙烯腈炭化制备碳纳米纤维

用静电纺丝的方法制得聚丙烯腈纳米纤维,并在250℃下预氧化,850℃下炭化,得到碳纳米纤维.用扫描电镜观察了静电纺纳米纤维、预氧化后的纳米纤维和炭化后的纳米纤维表面形态结构的变化,采用X射线衍射和红外光谱法分析了原料聚丙烯腈粉末、静电纺纳米纤维、预氧化后的纳米纤维和炭化后的纳米纤维内部结构的变化.     

改进静电纺丝法制备连续平行排列的聚合物纤维

介绍一种简单的静电纺丝新方法，它能够制造单轴平行排列的亚微米级纤维。相对于典型的静电纺丝装置，本装置使用两个相对放置的金属电极相应地与正负电压相连。纤维从两个喷丝头纺出以后合并成纱线，然后缠绕在高速旋转的圆形收集辊上。以这种方法制得的纤维具有连续、排列良好、收集区域大等优点．实验中以聚乙烯醇（PVA）和聚乙烯毗咯啉酮（PVP）为原料纺制定向排列的纤维。分析了纤维排列的形成原理，同时研究了溶液的浓度和卷取速度对纤维排列的影响。     

静电纺丝制备聚合物/无机物复合纳米纤维研究进展

利用静电纺丝技术制备的聚合物/无机物复合纳米纤维可以综合聚合物、无机物和纳米纤维三者的优点,表现出许多特殊的优异性能。介绍了国内外应用静电纺丝技术制备具有优良光学、电学、热学和力学性能的聚合物/无机物复合纳米纤维所取得的最新研究进展,指出了今后的研究热点及主要发展方向。     

静电纺丝多孔碳纳米纤维制备与应用研究进展

为更好地通过静电纺丝技术制备多孔碳纳米纤维,综述了近年来国内外静电纺丝技术实现工业化的可行性,静电纺丝制备多孔碳纳米纤维的方法、多孔结构类型以及多孔碳纳米纤维的应用等方面的最新进展。主要介绍了聚合物与聚合物共混以及聚合物与无机粒子共混静电纺丝多孔碳纳米纤维的2种方法的制备原理及所制得多孔碳纳米纤维的特点,并根据孔结构形状将多孔碳纳米纤维分为中空结构、介孔结构、多级孔结构和碳壳-蜂巢芯结构等类型。最后介绍了静电纺丝多孔碳纳米纤维在电化学、储氢、催化和吸附等领域的应用情况,并对未来多孔碳纳米纤维的发展前景进行了展望。     

电子纺丝法制备功能性纳米纤维

电子纺丝是一种由聚合物熔融或溶液纺丝液制备纳米级纤维(直径低于100m，长度可达千米)的方法电子纺丝时，采用不同的收集方法可以制备功能性纳米结构，如纳米管和纳米线等。过去几年电子纺丝的研究进展很快，并在众多领域展开应用研究。目前电子纺丝的研究主要集中在两方面：一是确定不同聚合物(包括生物聚合物)电子纺丝时的工艺参数；另一方面是进行深层次的机理研究，以期能控制纳米纤维的形态结构和表面性能，并探索合适的收集方法。本文从我国研究的实际情况出发，主要摘编了目前电子纺丝在应用方面的研究，希望能引起国内有关方面的重视，以尽快在这方面展开研究。     

远红外/抗菌多功能纳米纤维纱线的制备及其性能

将二氧化硅(SiO₂)和氧化锌(ZnO)纳米粒子添加到纺丝液中,利用静电纺丝将SiO₂/ZnO/PU纳米纤维沉积在均匀输送的棉网上,通过传统纺纱工艺制成远红外/抗菌多功能纳米纤维纱线,并对其织物的远红外发射率和抗菌性能进行表征。结果显示：SiO₂和ZnO粒子的协同作用可有效增强织物的远红外发射功能,其发射率随纳米粒子质量分数的增加而升高;质量分数为6%时,纳米纤维纱线具有较好的形貌与力学性能,同时具有较高的远红外发射率和优异的抗菌性能,远红外发射率为0.896,对大肠埃希菌和金黄色葡萄球菌的抑菌率为99.99%。     

用静电纺丝法制备可交联高性能聚合物纳米纤维

为解决高性能聚合物作为模板材料在烧蚀过程中会出现黏连或者成膜的问题,采用亲核缩聚法制备了含有10%烯丙基的羧基聚芳醚酮聚合物,利用静电纺丝法将该聚合物制成负载有镉离子的含羧基聚芳醚酮纳米纤维,将得到的纤维在紫外光的照射下交联固化,通过烧蚀得到氧化镉纳米纤维。通过扫描电子显微镜照片可看到：交联后的氧化镉纳米纤维形貌保持良好,而未经交联的模板煅烧后得到的纤维出现严重的熔融变形,甚至连成薄膜。纤维形态测试结果表明,经过交联后的聚合物复合纤维煅烧后得到的氧化镉纳米纤维结构保持完好,且直径比较均匀。可交联羧基聚芳醚酮在进行交联固化后能够保持良好的形貌特征,起到了很好的模板作用。     

碳纳米纤维负极材料制备及其电化学性能

为了获得性能优异的碳纳米纤维负极材料并对材料的碳化工艺进行探讨,利用静电纺丝技术和高温碳化制备一维碳纳米纤维负极材料。对获得的碳纳米纤维的形貌、化学成分结构及电化学性能进行测试分析,得到优化的预氧化和碳化条件。结果表明:在预氧化条件为250℃、120 min,碳化条件为800℃、120 min条件下制得的碳纳米纤维具有较好的形貌特征及化学性能,平均直径为190 nm,此时碳结构更加有序,碳含量达到73.7%。通过组装锂离子电池测试电池充放电性能,得到在100 mA/g的电流密度下,放电比容量达到568.4 mAh/g,经过100圈循环后容量保持率达77.3%。     

聚合物熔体法制备纳米纤维技术研究现状

针对聚合物熔体法生产纳米纤维效率低、性能不稳定,无法规模化应用的现状,对熔体法制备纳米纤维技术进行了综述。首先根据熔体法制备纳米纤维原理,对现有熔体法制备纳米纤维方法进行分类和对比分析,并结合研究现状,认为将不同单一纳米纤维制备方法进行有机组合是熔体法制备纳米纤维的发展趋势;然后详细综述了熔体法制备纳米纤维的工艺参数与纤维线密度之间的关系,揭示了熔体法纺纳米纤维细化技术的共性问题;最后介绍了熔体微分静电纺丝技术在纳米纤维制备方面的主要成果,通过机制揭示、工艺优化、材料改性等关键技术,熔体微分静电纺丝技术实现了平均直径小于500 nm 纤维的规模化制备。     

静电纺丝纳米纤维多功能敷料的研究进展

针对传统敷料缺乏复杂创面修复功能的问题,回顾了具有高比表面积、高孔隙率静电纺丝纳米纤维膜在多功能医用敷料领域的研究进展。首先从静电纺丝原理出发,讨论了各种静电纺丝纳米纤维制备方法的优势和局限性,然后重点介绍了静电纺丝纳米纤维材料在渗液管理、药物定向缓释、伤口监测及不同种类伤口修复中的应用,最后在阐明静电纺丝纳米纤维多功能敷料现存问题的基础上,指出多功能协同作用将是未来伤口敷料发展的重要方向之一。     

超声波酶法提取豆渣中水溶性多糖条件的优化

以水酶法提油后的副产物豆渣为原料,采用超声波协同纤维素酶法提取水溶性大豆多糖。在相同的超声波条件下(超声功率150W、超声温度88℃、超声时间17min、液固比28∶1、六偏磷酸钠溶液浓度2%)对水酶法提油后的豆渣进行预处理,在此基础上考察ViscozymeL复合纤维素酶对水溶性大豆多糖提取率的影响,首先对提取工艺进行单因素的选择,然后设计三因素三水平的正交实验,确定超声波协同纤维素酶法提取水溶性大豆多糖的最佳工艺条件为:液固比28∶1,酶解时间1.5h,酶解温度45℃,纤维素酶用量0.4%,pH4.0。在此条件下,超声波酶法的提取率为25.92%,与超声波法的水溶性大豆多糖的提取率(11.51%)相比,提高了14.41%。      

水性超细碳黑在N-甲基吗啉-N-氧化物溶液中的分散稳定性

 采用直接分散法和乳液聚合法分别制备了可用于Lyocell纤维原液着色用的水性分散型超细碳黑和包覆型超细碳黑,研究了不同方法得到超细碳黑的粒子大小以及在N-甲基吗啉-N-氧化物(NMMO)溶液中的分散稳定性。研究结果表明包覆型超细碳黑的平均粒径明显小于分散型超细碳黑,包覆型超细碳黑在NMMO溶液中的离心稳定性和耐热稳定性高于分散型超细碳黑,NMMO溶液中加入包覆型超细碳黑,其粘度明显下降,且加入量越大,粘度下降越明显。     

静电纺聚丙烯腈/线性酚醛树脂碳纳米纤维电极的制备及其性能

为研究炭化温度对碳纳米纤维电极性能的影响,采用静电纺丝法制备了聚丙烯腈/线性酚醛树脂(PAN/PF)纳米纤维,然后经不同温度炭化处理得到不同结构与性能的碳纳米纤维,并制备成电极材料.对碳纳米纤维的表面形貌、比表面积、孔结构、石墨化程度和元素含量,以及碳纳米纤维电极的电化学性能进行测试与表征.结果表明:PAN/PF碳纳米...     

亚临界水提取豆渣中可溶性大豆多糖工艺研究

考察了亚临界水提取豆渣中可溶性大豆多糖的最佳工艺条件。结果表明最佳提取条件为:亚临界水温度150℃,液料比35∶1,提取时间11 min,该条件下可溶性大豆多糖得率达22.8%。与传统提取方法相比,亚临界水提取法可明显缩短提取时间,并提高可溶性大豆多糖得率。     

莲心中可溶性成分的有效提取

采用不同的原料处理,改变提取的流程和提取时间，测定不同条件下所得提取液的可见吸收光谱，以此反映各提取液的组分和浓度是否发生变化，并比较在最大吸收波长下各提取液的吸光度大小，从而确定将莲心捣碎后，加热回流时间为60min的提取方法效果最佳。     

蜜环菌水溶性多糖的抗氧化活性研究

目的:通过蜜环菌水溶性多糖对·OH、O2-·和DPPH·三种自由基清除作用,评价其抗氧化性能,为蜜环菌药物制剂的活性研究及其产品的质量检测标准提供重要参考。方法:经热水浸提、除蛋白等步骤分离纯化到水溶性多糖,以抗坏血酸和TBHQ为对照,采用分光光度法评定其抗氧化特性。结果:蜜环菌水溶性多糖对三种自由基均有不同程度的清除活性,对三种自由基的清除能力是DPPH·>·OH>O2-·,当清除率达到90%以上时,清除DPPH·、·OH和O2-·的所需的多糖浓度分别为1.0、5.0、6.0mg·mL-1,蜜环菌多糖的清除能力显著。结论:蜜环菌水溶性多糖在体外具有较明显的抗氧化活性,在实验浓度范围内,抗氧化效果与浓度呈显著的线性相关。作为一种重要的天然活性物质,蜜环菌多糖的抗氧化活性和抗衰老作用将具有较高的应用价值。     

Removal of estrogenic pollutants from contaminated water using molecularly imprinted polymers

A synthetic molecularly imprinted polymer (MIP) sorbent for estrogenic compounds was prepared using a noncovalent imprinting technique. MIP microspheres sized from 1 to 2 microm were synthesized in acetonitrile by using alpha-estradiol as the template, acrylamide as the functional monomer, and trimethylpropanol trimethacrylate as the cross-linker. When compared with the nonimprinted polymer (NIP), the MIP showed outstanding affinity toward alpha-estradiol in aqueous solution with a binding site capacity (B(max)) of 380 nmol mg(-1) MIP, imprinting effect of 35, and a dissociation constant (Kd) of 38 microM. The MIP exhibited significant binding affinity toward other related estrogenic compounds such as beta-estradiol, diethylstilbestrol, estriol, and estrone, suggesting that this material may be appropriate for treating a complex mixture of estrogenic pollutants. The feasibility of removing estrogenic compounds from environmental water by the MIP was demonstrated using lake water spiked with alpha-estradiol. In addition, the MIP reusability without any deterioration in performance was demonstrated for at least five repeated cycles.     

Modeling semivolatile organic aerosol mass emissions from combustion systems

Experimental measurements of gas-particle partitioning and organic aerosol mass in diluted diesel and wood combustion exhaust are interpreted using a two-component absorptive-partitioning model. The model parameters are determined by fitting the experimental data. The changes in partitioning with dilution of both wood smoke and diesel exhaust can be described by two lumped compounds in roughly equal abundance with effective saturation concentrations of approximately 1600 microg m(-3) and approximately 20 microg m(-3). The model is used to investigate gas-particle partitioning of emissions across a wide range of atmospheric conditions. Under the highly dilute conditions found in the atmosphere, the partitioning of the emissions is strongly influenced by the ambient temperature and the background organic aerosol concentration. The model predicts large changes in primary organic aerosol mass with varying atmospheric conditions, indicating that it is not possible to specify a single value for the organic aerosol emissions. Since atmospheric conditions vary in both space and time, air quality models need to treat primary organic aerosol emissions as semivolatile. Dilution samplers provide useful information about organic aerosol emissions; however, the measurements can be biased relative to atmospheric conditions and constraining predictions of absorptive-partitioning models requires emissions data across the entire range of atmospherically relevant concentrations.     

滑子菇水溶性多糖提取工艺的研究

探讨了以滑子菇为原料提取水溶性多糖的最佳工艺条件,实验结果表明:料液比为1∶60、温度为80℃、浸提时间为5h,为提取滑子菇多糖的最佳工艺条件,产率达1.685%。     

Silver migration from silver-modified activated carbon applied as a water filtration medium in classic cartridges of jug filter systems

A comprehensive study was undertaken in order to examine the possible adverse effect of jug filter systems (JFSs) on the quality of filtered water taking into account the released amounts of silver (Ag) into the filtered test water. Nine brands of JFSs (A–I) were investigated according to BS 8427:2004 using a validated ICP/MS method. Essential modification of BS 8427:2004 within the domain of the composite sample preparation was proposed and applied during the tests. The established grand mean concentrations of released Ag from A–H classic cartridges (containing Ag-modified activated carbon and ion exchange resins) and I classic cartridge (containing non-modified activated carbon and ion exchange resin) installed in corresponding JFSs were in the range of 2.6–13.1?µg?l^?1 and lower than 0.014?µg?l^?1, respectively. These values were applied for the estimation of the daily intakes of Ag connected with the consumption of water filtered using JFSs (ranging from?<?0.0004 to 0.374?µg?kg^?1?day^?1). After taking into account the grand mean concentrations of Ag established during the whole cycle of exploitation for nine JFSs and on the basis of available toxicological data for this element, no long-term risk for human health with respect to appearance of argyria (a condition caused by improper exposure to the Ag or Ag compounds) could be expected (the Hazard Quotient indices estimated as ratios of the daily intakes to the reference dose of Ag were equal or lower than 0.075). Ag-modified activated carbon is not included in the positive list of the authorised substances of the European Commission Regulation (EU) No. 10/2011. Additionally, this material has not been approved by European Food Safety Authority (EFSA). A part of water filtered by JFSs can be directly consumed as drinking water and additionally the remaining water can be applied for the preparation of food products (drinks, soups, etc.). In both cases the quality of water has to fulfil the requirements listed in Directive 98/83/EC (Regulation (EC) No. 178/2002 defines the quality of water intentionally incorporated into the food after the point of compliance as defined in Article 6 of Directive 98/83/EC). However, it should be underlined that point-of-use water treatment units (including JFSs) are not regulated under Directive 98/83/EC and additionally the parametric value for Ag is not included in this document. Therefore, a provisional migration limit for Ag leached from JFSs at the level of 25?µg?l^?1 was proposed. This value for Ag would limit intake to less than 13% of the human No Observed Adverse Effect Level (NOAEL) (0.39?mg person^?1?day^?1), using an assumption that each day 2?L of filtered water is consumed containing this metal at the provisional migration limit. All the JFSs tested meet this requirement.