Preparation of carbon nanotubes with iron nanowires inside using a simple microwave-based method

The importance of synthesizing carbon nanotubes with iron nanowires inside (Fe-MWNTs) via microwave radiation lies in the fact that it allows to improve aspects such as selective and uniform heating of the sample, reduction of the time of synthesis, avoiding complex experimental procedures and lowering the cost of production. In this paper we synthesize and characterize carbon nanotubes with iron nanowires inside using a mixture of graphite and iron acetate powders as starting materials and a 900 W domestic microwave oven used as power source. A mixture of the starting materials inside a vacuum sealed quartz ampoule was subjected to radiation for 7 min. As a result straight Fe nanowires are obtained with lengths between 5 and 15 microns, and a wide variety of partially Fe filled nanotubes with diameters in the 30–80 nm range. Samples were characterized with scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.     

NF系列复合膜的制备及结构性能的研究

采用界面缩聚的方法制备了NF系列复合纳滤膜 ,并对其进行了表征 .在 0 6MPa下 ,NF - 1的水通量为 4 1L/(m2 ·h) ,对Na2 SO4 的截留率为 78% ,NF - 2的水通量为 6 0L/(m2 ·h) ,对Na2 SO4 的截留率为 94 % ,NF - 3的水通量为 2 6 5L/(m2 ·h) ,对Na2 SO4 的截留率为 94 % .通过红外光谱和原子力显微镜观察到NF系列复合纳滤膜的表层化学结构和表面形貌 ,探索了NF系列纳滤膜在染料工业的应用前景     

pH敏感型管式陶瓷复合膜的制备

采用硅烷偶联剂KH-570在乙醇溶剂中以盐酸溶液为催化剂进行水解后对管式ZrO2陶瓷膜进行表面修饰,进一步用化学接枝法将丙烯酸单体接枝到改性ZrO2陶瓷膜上,制备pH敏感型陶瓷复合膜.系统考察了不同偶联反应条件对氧化锆陶瓷膜的硅烷化改性效果的影响;研究了丙烯酸单体浓度对pH敏感膜渗透通量及pH开关系数的影响.通过扫描电镜(SEM)、X射线光电子能谱(XPS)、热重(TG)及水通量测定等对改性前后膜结构和pH敏感性能进行分析.结果表明,在以乙醇为溶剂进行硅烷化改性后,成功引入了碳-碳双键,并将丙烯酸成功接枝在陶瓷膜表面;单体浓度对pH敏感的膜通量及pH开关系数有重要的影响;所制备膜显示了良好的pH敏感性能.     

硅橡胶-聚碳酸酯富氧膜的制备

以聚碳酸酯(PC)为膜材料,N-甲基吡咯烷酮(NMP)为溶剂,γ-丁内酯(γ-GBL)为添加剂,水为凝胶浴,采用浸入沉淀相转化法制备平板膜.在其表面涂敷聚二甲基硅氧烷(PDMS),制备了硅橡胶-聚碳酸酯复合膜.利用扫描电子显微镜表征基膜微观结构,以氧气渗透速率和氧氮选择性为指标,考察了聚合物/溶剂配比、添加剂浓度及硅橡胶浓度对膜性能的影响.结果表明,当PC浓度为17%,γ-GBL浓度为23%时,复合膜具有稳定的气体分离性能,其氧气渗透速率为233 GPU.     

复合陶瓷薄膜的制备及其分离应用

介绍了复合陶瓷薄膜的制备研究以及它们在气体、液体分离方面的应用。复合陶瓷薄膜继承了单纯组分陶瓷薄膜的优点，并且由于其丰富的表面特性，在表面改性和分离应用方面展现了巨大的潜力。     

聚酰胺复合纳滤膜的制备与表征

以聚砜超滤膜为基膜,通过间苯二胺(PDA)与均苯三甲酰氯(TMC)界面聚合制备聚酰胺复合纳滤膜.系统地考察了界面聚合条件对所得复合膜性能的影响及膜对不同类型的无机盐的分离性能.详细表征了基膜与复合膜的表面形貌和接触角.结果表明:最佳聚合条件为:PDA质量分数1.5%,TMC质量分数0.1%,水相浸泡时间3min,反应时间20s,热处理温度80℃,热处理时间3min.在0.6MPa下,对2 000mg/L的MgSO4的截留率和通量分别为95.6%和7L/(m2·h).复合膜对四种不同类型无机盐的截留率的次序依次为Na2SO4MgSO4NaClMgCl2.此外,表面形貌和接触角研究表明通过界面聚合在基膜表面形成了一层聚酰胺功能层.     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率。结果表明,SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20%时,膜的含水率和溶胀度分别达到18%和2.1%。通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20%的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm。     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

开发价格低廉且性能优异的质子交换膜是目前燃料电池研究的热点.采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率.结果表明SPPO与ZrP产生相互作用使SPPO结构发生变化.SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20％时,膜的含水率和溶胀度分别达到18％和2.1％.通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20％的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm.     

Lossless image compression using a simple prediction method

This article describes a new straightforward technique for lossless image compression, entitled simple prediction method, which results in compression ratios similar to those achieved by the most powerful techniques described in the literature. The predictive model used by the method is one in which the current point is predicted as a weighted average of the preceding neighbouring points. The weights for this mask are encoded within the compressed image. The difference between this prediction and the actual value is generally small with a symmetric exponential distribution, and this difference is represented using arithmetic encoding. © 1996 John Wiley & Sons, Inc.     

Preparation of high-purity and ultrafine WC-Co composite powder by a simple two-step process

In this study, high-purity and ultrafine WC-6%Co composite crystallites was synthesized by a simple two-step process consisting of the precursor-formation of the mixture of blue tungsten oxide (WO_2.9) and cobaltic oxide (Co₂O₃) and the following deep reduction and carburization with CH₄-H₂ mixed gases. The experimental results revealed that after the first carbothermic reduction stage at 1050 or 1150 °C, a mixture of W, WO₂ and Co₇W₆ was obtained, which was further carburized to the WC and Co phases by CH₄-H₂ mixed gases at 900 °C. With the increase of C/WO_2.9 molar ratio, the particle sizes of first-stage precursor and carbonized product were both decreased. The particle sizes of final products are mainly determined by C/WO_2.9 ratio and reaction temperature at the first stage. When the C/WO_2.9 ratio was in the range of 2.3–2.7, the high-purity WC-6%Co composite powder with the average particle sizes of 160–410 nm could be obtained.     

有序介孔复合炭膜的制备及其性能研究

采用软模板法合成有序介孔炭(OMC),利用XRD、TEM及SEM等分析方法对其进行结构性能分析,探讨了催化剂和模板剂的种类及用量、反应温度等合成工艺条件对形成OMC结构性能的影响。以最佳工艺条件制备的OMC前驱体为涂膜液涂敷在管状微滤炭膜表面,经炭化制得有序介孔复合炭膜,而后考察了复合炭膜的气体渗透性能。结果表明:以盐酸为催化剂、模板剂F127/间苯二酚摩尔比为0.0081、反应温度为30℃时,可合成有序程度最佳的OMC前驱体。用该OMC前驱体涂敷微滤炭膜制备的有序介孔复合炭膜,改善了微滤炭膜的孔结构,最大孔径由0.530μm减小至0.299μm,同时提高了炭膜的气体渗透通量。其中,由混煤微滤炭膜所制有序介孔复合炭膜,N2气渗透通量达1.18·10-8m3·m-2·s-1·Pa-1,是未经修饰烟煤微滤炭膜的4倍。     

纳米氧化物/Nafion复合膜的制备与性能表征

分别以SiO2、TiO2、Al2O3和ZnO等纳米氧化物为改性剂,采用流延法制得纳米氧化物/Nafion复合膜.XRD和ATR/FT-IR分析表明纳米氧化物在复合膜均匀分散,也没有发生团聚现象.对复合膜的质子传导和阻醇性能进行了测定,结果发现,纳米氧化物/Nafion复合膜具有较好的质子传导性能;阻醇性能均有较大幅度的提高,且以SiO2和TiO2改性的Nafion膜最为明显,甲醇透过系数分别从约10降低到约10-7和10-8数量级.这说明纳米氧化物/Nafion复合膜是一类较好的直接甲醇燃料电池用质子交换膜材料.     

PTFE-PDMS/PET复合膜制备及其渗透汽化性能

以聚四氟乙烯(PTFE)微粉填充聚二甲基硅氧烷(PDMS)硅橡胶膜为活性皮层和PET无纺布为底膜,制备了PTFE-PDMS/PET渗透汽化复合膜并用于分离乙醇水溶液,分析了复合膜结构、疏水性、力学性能及溶胀性能.研究表明,随着PDMS复合膜中PTFE含量(质量分数,下同)增加,复合膜结晶度及水接触角增加;断裂伸长率和拉伸强度均呈现先增加后减小的趋势;膜溶胀度呈线性减少.复合膜渗透汽化选择性α和乙醇渗透系数J_E随PTFE含量的增加先增加后减少,而水渗透系数J_W呈逐渐减小的趋势,当PTFE填充量为10%时,乙醇渗透系数J_E最大.     

渗氢用非对称性复合陶瓷膜的制备技术

简要介绍了渗氢用非对称性复合陶瓷膜的发展状况，着重介绍了载体的制备，载体表面涂覆技术和钯合金膜的沉积技术。     

Preparation of a new class of polymeric composite membranes and their application in pervaporation

The preparation of composite membranes consisting of thin films of polymeric networks sustained by thicker porous supports is described. The structure of the membranes was observed with the aid of a scanning electron microscope. The membranes were tested in a vacuum pervapouration unit with a water-ethanol solution containing 10 wt % alcohol. Free dense films of the same polymeric networks were also prepared in order to compare their pervapouration performance with that of composite membranes.     

Preparation of carbon sphere from corn starch by a simple method

Carbon spheres with a regular and perfect shape was successfully synthesized from corn starch by a two stage process: oxidation and carbonization. In this process, oxidation treatment was the main step; the optimal oxidation temperature was 210 °C. The resulting products were characterized by using combined techniques including X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The results showed that the products could keep the original shape of corn starch perfectly, and the diameters of carbon spheres ranged from 5 to 25 μm. It showed characteristic structure of non-graphitizing carbons heated at high temperatures. The preparation mechanism has also been discussed.     

埋砂复合电沉积法制备铜基金刚石复合材料

铜基金刚石复合材料可结合铜与金刚石的优良物理性能,实现航空电子系统及其元器件轻质、高导热、低膨胀的性能要求。考察了复合电沉积工艺对复合材料金刚石质量分数和致密度的影响;通过对埋砂复合电沉积的预镀时间、上砂镀时间以及加厚镀时间等工艺参数的优化,获得金刚石分布均匀,致密度较高的铜基金刚石复合材料;并根据3种粒径金刚石的埋砂工艺参数拟合了金刚石粒径与复合电沉积工艺的关系。     

Preparation and characterization of magnetic nanofibrous composite membranes with catalytic activity

Magnetic nanofibrous composite membranes were electrospun from the mixtures of poly(acrylonitrile-co-acrylic acid) (PANCAA) and Fe₃O₄ nanoparticles. Field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were used to characterize the composite membranes. TGA results indicate that the addition of Fe₃O₄ nanoparticles catalyzes the carbonization of PANCAA as well as dramatically increases the carbonization temperature. The intrinsic peroxidase-like activity of Fe₃O₄ nanoparticles was measured by the color reaction of phenol/4-amino antipyrine in the presence of H₂O₂. Under optimal conditions, the electrospun composite membranes show high peroxidase-like catalytic activity and reusability. Taking into account of the potentiality for separation, these as-prepared magnetic nanofibrous composite membranes will be applied in phenolic wastewater treatment.     

基于复合纳米颗粒的有机-无机杂化膜制备与性能表征

采用共混杂化的方法,利用Al2O3/TiO2复合纳米颗粒对疏水性强、易污染的聚偏氟乙烯膜进行改性,以增强其在水相溶液中的应用能力。通过测定纯水通量、截留率和膜表面接触角分别考察膜的透过、分离性能及亲疏水性能。用扫描电镜观察杂化膜的表面形态及断面结构。用傅立叶红外光谱分析杂化膜的化学结构,用X射线衍射分析杂化膜的结晶状态。膜的抗污染性能由料液通量试验考察。改性前后膜的测试结果表明,纳米颗粒的加入改善了聚偏氟乙烯膜的通量、亲水性能和抗污染性能。     

负载型TiO2-聚丙烯疏水复合膜的制备与表征

采用热致相分离 (TIPS)技术制备浸涂型和反应型硅藻土 -聚丙烯疏水复合膜 ,用SEM、氮吸附、红外光谱和气体渗透性能测试装置等方法表征不同的制膜方法、浸膜液浓度及冷却方式等因素对膜形态、结构和气体渗透性能的影响 .结果表明 :浸涂型聚丙烯膜球形颗粒和孔径尺寸均小于反应型聚丙烯膜 ;TiO2 -聚丙烯膜与硅藻土陶瓷支承体是通过Si—O—Ti—O—C键的价联方式形成键联型复合膜层 ;在膜内 ,气体渗透由Knudsen扩散控制 ,H2 O与N2 的分离因子分别为 2 .4 6和 2 .2 2 .