4,4'-二氨基二苯醚二苯酮固化环氧树脂/粘土纳米复合材料的研究

采用离子交换法, 用十六烷基三甲基溴化铵处理钙基蒙脱土(MMT), 使蒙脱土的层间距由1.49 nm扩大到2.21 nm, 制备了环氧树脂/ BADK/MMT纳米复合材料, 并用XRD等手段研究了有机蒙脱土在环氧树脂中的插层及剥离行为. 研究结果表明, 蒙脱土含量及环氧树脂与有机土的混合温度和时间均对固化后复合材料的剥离产生影响, 只有在特定条件下才能得到剥离型纳米复合材料.     

双单体原位接枝插层法制备聚丙烯纳米复合材料的研究Ⅰ.制备、表征及力学性能的研究

用有机插层剂处理蒙脱土原土 ,制得有机蒙脱土 (O MMT) .采用双单体 (马来酸酐和苯乙烯 )原位接枝插层法 ,制备了聚丙烯 蒙脱土纳米复合材料母料 .将母料与聚丙烯基体在双螺杆上共混挤出 ,制得聚丙烯 蒙脱土纳米复合材料 (PP Montmorillonetenanocomposites,PMNC) .这是制备聚合物纳米复合材料的一种新方法 .通过X 射线衍射测试 (XRD)表明 ,有机蒙脱土片层 0 0 1面间距从原土的 1 4 9nm扩大到 2 96nm ,复合材料中蒙脱土片层 0 0 1面间距由有机蒙脱土的 2 96nm扩大到 4 0nm .力学性能测试表明 ,复合材料的力学性能明显优于PP基体 ,在提高材料拉伸强度的同时 ,缺口冲击强度也得到很大的提高 .用扫描电镜 (SEM)对材料的冲击断面形貌进行了研究 ,并从理论上分析了断裂机理 .随着蒙脱土含量的增加 ,冲击断裂形式逐渐从脆性断裂变成韧性断裂     

不同链长的聚醚铵阳离子协同插层对蒙脱土性能的影响

为了制备高性能的聚合物/蒙脱土纳米复合材料, 必须对蒙脱土(MMT)进行有机改性来改善蒙脱土表面的疏水性、提高蒙脱土与聚合物之间的相容性, 同时也需要尽可能地增大蒙脱土的层间距. 为此, 提出了一种采用不同链长的聚醚铵阳离子协同插层MMT 的新方法, 即采用D2000(或T5000)聚醚铵盐与D400 聚醚铵盐协同插层MMT, 并采用X射线衍射分析(XRD)和热重分析(TGA)研究了协同插层对改性MMT 的层间距、有机含量以及耐热性的影响. 另外, 也研究了插层过程中的搅拌方式和D400 聚醚铵盐多次插层对改性MMT 的层间距、有机含量等的影响. 研究结果表明,采用长链聚醚铵阳离子协同插层更有利于提高D400 聚醚铵盐改性MMT 的层间距和有机含量; T5000 协同插层MMT中总的有机含量(64.06%)进一步增加, 这可能是因为T5000 的支链在MMT 层间形成的笼型结构既提供了更大的空隙,又起到了屏蔽作用, 同时也得到了较大的层间距(6.86 nm).     

聚萘并噁嗪/蒙脱土纳米复合材料的制备与表征

用原位插层反应法地制备了聚萘并嗪 蒙脱土纳米复合材料 .采用X ray衍射 (XRD)及透射电镜(TEM)研究复合材料中蒙脱土硅酸盐片层间距 ,发现硅酸盐片层间距由 1 2 6nm扩增至 5 88nm以上 .同时研究了该复合材料的耐热性 ,并探讨了复合材料的结晶行为     

高抗冲聚苯乙烯/蒙脱土复合材料的阻燃性研究

用经十六烷基三甲基溴化铵有机化改性的蒙脱土 (OMMT)与高抗冲聚苯乙烯 (HIPS)通过熔融插层法制备了HIPS OMMT复合材料 ,用X ray衍射技术对材料结构进行了表征 ,发现钠基蒙脱土 (Na+ MMT)和有机蒙脱土的层间距分别为 1 5 1nm和 2 18nm ,HIPS OMMT(5phr)复合材料中蒙脱土的层间距因聚合物大分子的插入扩大为 3 4 4nm ;而HIPS与Na+ MMT形成的复合材料的层间距与Na+ MMT的层间距相比却没有变化 ,表明未有机化处理土没有形成插层结构 .锥形量热仪的研究结果表明HIPS OMMT复合材料的热释放速率、质量损失速率以及生烟速率等燃烧特性参数均显著降低 ,具有较明显的阻燃性和抑烟性 ,而HIPS Na+ MMT非插层型复合材料只有在Na+ MMT很高填充量下 (>2 0phr)才有一定阻燃效果 .比较了铵盐对HIPS阻燃性的影响 ,结果表明铵盐自身的阻燃作用很小 ,主要是插层复合结构起阻燃作用 .     

不同分子量壳聚糖对蒙脱土插层复合物的影响

于醋酸溶液中通过溶液插层技术将不同分子量的壳聚糖与钠基蒙脱土进行插层复合,制备了系列壳聚糖/蒙脱土插层复合物. 通过XRD、TEM、FTIR测试技术对插层复合物的结构进行了表征. 结果表明,仅通过醋酸溶液处理,残留的HAc就可使MMT层间距由原来的1.3 nm增加至1.55 nm,并使结构规整性提高;降低壳聚糖分子量有利于MMT层间距增大,并出现更多剥离形态的蒙脱土;当壳聚糖分子量为4.1×104时,最大层间距可达2.48 nm,但进一步降低壳聚糖分子量层间距反而略微减小;红外光谱分析表明,插层复合物中壳聚糖与蒙脱土间存在明显的静电作用. TGA分析结果表明,插层复合物中壳聚糖的含量随分子量的降低而增加,残留的醋酸使插层复合物中壳聚糖的热稳定性能下降.     

原位聚合法制备超疏水的聚乙烯纳米复合材料

采用一种新方法将Ziegler-Natta催化剂组分TiCl4和MgCl2负载到蒙脱土(MMT)的层间,制备了TiCl4/MgCl2/MMT插层型催化剂.利用Ziegler-Natta催化剂特有的"形态复制效应",通过乙烯原位聚合制备出了表面具有花瓣状形态的聚乙烯纳米复合材料.这种聚乙烯纳米复合材料的表面与水的接触角达到(152.2±0.8)°,呈现超疏水性质.     

聚苯胺/离子液体/蒙脱土纳米复合材料的制备及其导电性能研究

采用1-羧甲基-3-甲基咪唑氯化盐离子液体对钠化蒙脱土进行插层改性,然后用苯胺的盐酸溶液进行二次插层,以过硫酸铵为氧化剂,盐酸溶液为掺杂剂,使进入离子液体/蒙脱土(CMMIm/MMT)层间的苯胺(An)发生氧化聚合反应,制备了一种具有良好导电性的聚苯胺/离子液体/蒙脱土复合材料(PANI/CMMIm/MMT).用红外光谱、X-射线衍射,热重分析和DSC对样品进行了表征.结果表明当离子液体/蒙脱土用量为7.5%、盐酸浓度为1mol/L、过硫酸铵与苯胺的摩尔比为1∶1、0℃下反应6h时制备的PANI/CMMIm/MMT纳米复合材料电导率最高,达到了0.3S/cm,是相同条件下聚苯胺/钠化蒙脱土纳米复合材料电导率的2.5倍,聚苯胺的7.5倍.     

聚丙烯/蒙脱土纳米复合材料Ⅰ.制备、表征及动态力学性能

用原位接枝插层法成功地制备了聚丙烯 /蒙脱土纳米复合材料 (PPMNC) .采用X射线衍射研究复合材料中蒙脱土硅酸盐片层间距 ,发现硅酸盐片层间距从 1 94nm升至 4nm左右 .同时研究了PPMNC的动态力学性能 ,结果表明 :PPMNC的动态储能模量明显高于聚丙烯 (PP) ,尤其在T >Tg 高温段 ,甚至可以达到PP基体的 2倍     

甲苯-2,4-二异氰酸酯修饰蒙脱土及聚苯乙烯蒙脱土纳米复合材料的制备与表征

用FTIR和WAXD法研究了甲苯-2,4-二异氰酸酯(TDI)的邻位和对位异氰酸酯基团与蒙脱土表面羟基的修饰反应,在此基础上提出了结构模型;用TDI修饰后的蒙脱土成功制备了插层型聚苯乙烯/蒙脱土纳米复合材料,并用WAXD和TEM进行了表征.实验结果表明,修饰后TDI与蒙脱土表面形成化学键,使蒙脱土的片层间距显著增大,十六烷基三甲基溴化铵(CTAB)在蒙脱土层间由双层平行排列转变为双层脂肪链倾斜方式排列.在苯乙烯插层聚合过程中,蒙脱土层间距进一步扩大,其初级粒子在聚苯乙烯基体中的厚度约20～50nm.     

Adsorption and co-adsorption of ethylene and carbon monoxide on silica-supported monodisperse Pt nanoparticles: volumetric adsorption and infrared spectroscopy studies

The adsorption of carbon monoxide and ethylene, and their sequential adsorption, was studied over a series of Pt/SBA-15 catalysts with monodisperse particle sizes ranging from 1.7 to 7.1 nm by diffuse-reflectance infrared spectroscopy and chemisorption. Gas adsorption was dependent on the Pt particle size, temperature, and sequence of gas exposure. Adsorption of CO at room temperature on Pt/SBA-15 gives rise to a spectroscopic feature assigned to the C-O stretch: nu(CO) = 2075 cm-1 (1.9 nm); 2079 cm-1 (2.9 nm); 2082 cm-1 (3.6 nm); and 2090 cm-1 (7.1 nm). The intensity of the signal decreased in a sigmoidal fashion with increasing temperature, thereby providing semiquantitative surface coverage information. Adsorption of ethylene on Pt/SBA-15 gave rise to spectroscopic features at approximately 1340, approximately 1420, and approximately 1500 cm-1 assigned to ethylidyne, di-sigma-bonded ethylene, and pi-bonded ethylene, respectively. The ratio of these surface species is highly dependent on the Pt particle size. At room temperature, Pt particles stabilize ethylidyne as well as di-sigma- and pi-bonded ethylene; however, ethylidyne predominated on the surfaces of larger particles. Ethylidyne was the only identifiable species at 403 K, with its formation being more facile on larger particles. Co-adsorption experiments reveal that the composition of the surface layer is dependent on the order of exposure to gases. Exposure of a C2H4-covered Pt surface to CO resulted in an approximately 50% decrease in chemisorbed CO compared to a fresh Pt surface. The nu(CO) appeared at 2050 cm-1 on Pt/SBA-15 pretreated with C2H4 at room temperature. The di-sigma-bonded and pi-bonded species are the most susceptible to displacement from the surface by CO. The formation of ethylidyne appeared to be less sensitive to the presence of adsorbed carbon monoxide, especially on larger particles. Upon exposure of C2H4 to a CO-covered Pt surface, little irreversible uptake occurred due to nearly 100% site blocking. These results demonstrate that carbon monoxide competes directly with ethylene for surface sites, which will have direct implications on the poisoning of the heterogeneously catalyzed conversion of hydrocarbons.     

Redox properties of vanadium ions in SBA-15-supported vanadium oxide: an FTIR spectroscopic study

The state of vanadium ions in VxOy/SBA-15 (2.7 wt % V) was studied with FTIR spectroscopy using CO and NO as probe molecules. Neither CO (at 85 K) nor NO (at RT) adsorb on the oxidized sample because of the coordinative saturation of V5+ ions and the covalent character of the V5+=O bond. After treatment of the sample in 50 kPa H2 at 673 K, the V5+ ions are reduced to two different types of V3+ sites, as manifested by carbonyl bands at 2189 and 2177 cm-1. In the presence of O2 at 85 K, thus formed V3+ ions are partly oxidized to V4+ sites showing carbonylic bands at 2202 and 2190 cm-1. When the reduced sample is exposed to O2 at room temperature, the V3+ ions are fully oxidized to V5+. The adsorption of NO on the reduced VxOy/SBA-15 shows that the V3+ and V4+ ions possess two effective coordinative vacancies and as a result can adsorb two NO molecules forming the respective V3+(NO)2 and V4+(NO)2 dinitrosyls. The introduction of O2 to the VxOy/SBA-15-NO system leads to reoxidation of the V3+ and V4+ ions to V5+ and formation of bridged (1639 cm-1) and bidentate (1573 cm-1) surface nitrates. After coadsorption of CO and NO on the reduced sample the formation of surface mixed carbonyl-nitrosyls (2108 and 1723 cm-1) was observed for the first time.     

新铌酸盐Sr5NdTi3Nb7O30的合成与介电特性

一些铁电铌酸盐具有优良的电光性能和非线性光学性能,因此该类化合物的人工合成、结构与性能的研究受到了重视,其中钨青铜结构的系列晶体(例如SBN、KNSBN、SCNN)在材料的制备和器件的设计方面都取得了很大进展,它们在实时全息存储、集成     

Permanent Trapping of CO(2) in Single-Walled Carbon Nanotubes Synthesized by the HiPco Process

Infrared spectroscopy is used to study trapped and physisorbed CO2 in single-walled carbon nanotube bundles (SWNTs) synthesized by the HiPco process. CO2 is entrapped within the SWNTs by acid oxidation of the unpurified sample followed by vacuum heating to 700 K. The trapped CO2 has a single nu3 mode at 2327 cm-1, is stable during temperature cycling from 77 to 700 K, and remains after venting to room air. CO2 physisorption studies show a nu3 mode at 2330 cm-1 for the as-received HiPco samples, 2340 cm-1 for the acid-oxidized sample, and 2327 and 2340 cm-1 for the oxidized sample after vacuum heating. The sites responsible for the infrared peaks of the physisorbed and trapped species are discussed.     

氮杂环卡宾银碘化物[Ag(MEIm)2]+[AgI2]-的合成、结构与催化性能(MEIm=1-methyl-3-ethyl-imidazolyl)

常温下(MEIm)+I-(MEIm=1-methyl-3-ethyl-imidazolyl)与Ag2O按照物质的量比为1∶2在DMSO中反应成功的合成了线型氮杂环卡宾银碘化物[Ag(MEIm)2]+[AgI2]-,化合物通过了元素分析,1H NMR,X-ray衍射表征。配合物属于单斜晶系,空间群为C2/m,a=1.592 5(4)nm,b=0.679 07(14)nm,c=0.927 1(2)nm,β=110.247(5)°,V=0.940 7(4)nm3,Mr=689.86,Z=8,Dc=2.436 g.cm-3,μ(Mo Kα)=5.36 mm-1,F(000)=640,R=0.036,wR=0.105。配合物由阴阳离子对构成,配阳离子中2个卡宾碳原子与银原子呈线型结构。目标化合物对L-lactide的聚合具有高的催化活性。     

Spectrophotometric Study on the Interaction between Arsenazo M and Proteins

Dye binding protein assays are commonly used in biochemical and clinical laboratories, and the reaction mechanism is still under investigation1-2. In this paper, the interaction of Arsenazo M with serum proteins was studied. Procedure In most experiments, 1.20 mL of Arsenazo M (5.0010-4 mol/L), 2.0 mL of C-L buffer solution, 3.0 mL alcohol and certain amount of protein standard solutions or samples were added to 10 mL volumetric flasks, then diluted to mark with water, and mixed thor…     

Growth and Spectral Properties of Yb^3＋-doped Ba3Gd（BO3）3 Crystal

Crystal of Yb3+-doped Ba3Gd(BO3)3 has been grown by the Czochralski method. The spectroscopic characterizations have been investigated at room temperature. The Yb3+:Ba3Gd(BO3)3 crystal exhibits broad absorption at 976nm with FWHM of 7nm and large overall spitting of 2F7/2 manifold (823cm-1). The absorption and emission cross sections are 5.09×10-21cm2 at 976nm and 0.97×10-21cm2 at 1040nm,respectively. The fluorescence lifetime is 2.84 ms.     

Morphology study of layered silicate/chitosan nanohybrids

Modification of clay with biopolymers has been of high interest in recent years. These new materials may be used for drug delivery systems and as biomaterials due to their high biocompatible properties and because they have the advantage of being biodegradable. The modification of montmorillonite (MMT) with chitosan was done in solution, at ratio 1:2 and at room temperature, or at stages of high temperature, and subjected to a microwave treatment. The influence of pH was observed upon the intercalation process.The obtained materials were characterized through X‐ray diffraction (XRD), thermogravimetrical analyses (TGA), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using such a mixed treatment, the basal distance of modified MMT increased up to 3.6 nm. The results show the intercalation of chitosan between the layers of MMT and obtaining of intercalated and partial exfoliated nanocomposites. Copyright © 2011 John Wiley & Sons, Ltd.     

聚N-甲基苯胺/蒙脱土纳米复合材料的合成及其协同电流变效应

用插层聚合法制备了聚N 甲基苯胺 蒙脱土纳米复合材料微粒 ,通过IR、XRD及TEM对其结构进行了表征 .观察发现聚N 甲基苯胺插入蒙脱土层间后 ,蒙脱土片层间距由 0 96nm扩大至 1 34nm .将其分散在甲基硅油中 (2 0wt% )配制成无水电流变液 ,该复合材料表现出显著的协同效应 ,具有较好的电流变行为 .实验表明在电场作用下聚N 甲基苯胺 蒙脱土纳米复合材料的电流变效应比聚苯胺、蒙脱土都有显著提高 ,在 3kV mm(DC ,74 5s- 1 )时 ,剪切强度达 6 0kPa ;同时抗沉降性极好 ,静置 6 0天沉淀率小于 3% .介电性能测试表明聚N 甲基苯胺 蒙脱土纳米颗粒的介电常数和介电损耗较蒙脱土和聚N 甲基苯胺明显提高 ,电导率也达到了最佳范围 .     

溶液成膜的温度对聚对苯二甲酸乙二酯结晶度的影响

<正> 用溶液成膜是制备聚合物薄膜的常用方法之一。但是溶液成膜的条件,如成膜温度,溶液浓度等对半结晶聚合物结晶度的影响研究报道较少。制备聚对苯二甲酸乙二酯(PET)非晶态薄膜通常使用熔融热压其后淬火的方法。由于PET在熔点附近易于降解,在薄膜中产生气泡,因而很难制备较大面积的均一厚度的薄膜,如在拉伸试验中所需