交联1,4—顺式聚丁二烯的取向结晶

用ＷＡＸＤ和ＳＡＸＳ研究交联１，４－顺式聚丁二烯的取向结晶。结果表明：该试样在拉伸状态时，形成折叠链片晶，而不是伸直链纤维晶。片晶之间断产生新的片晶，使长周期减小，并且片晶的横向尺寸不断增大，由此导致结晶度增大。     

Cyclic Voltammograms of Ferrocene on Multi‐Walled Carbon Nanotubes (MWCNTs)‐Modified Edge Plane Pyrolytic Graphite (EPPG) Electrode in Room Temperature Ionic Liquids (RTILs) of 1‐Ethyl‐3‐Methylimidazolium Tetrafluoroborate (EMIBF4)

In this work, the electrochemical behavior of ferrocene (Fc) was investigated by cyclic voltammetry (CV) in room temperature ionic liquids (RTILs) of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF₄) on glass carbon (GC), edge plane pyrolytic graphite (EPPG) and multi‐walled carbon nanotube (MWCNTs)‐modified EPPG electrodes, respectively. The results demonstrated that on GC electrode, pairs of well‐defined reversible peaks were observed, while for the electrode of EPPG, the peak potential separation (ΔE_p) is obviously larger than the theoretical value of 59 mV, hinting that the electrode of EPPG is distinguished from the commonly used electrode, consistent with the previous proposition that EPPG has many “defects”. To obtain an improved electrochemical response, multi‐walled carbon nanotubes (MWCNTs) were modified on the electrode of EPPG; the increased peak current and promoted peak potential separation not only proved the existence of “defects” in MWCNTs, but also supported that “creating active points” on an electrode is the main contribution of MWCNTs. Initiating the electrochemical research of Fc on the MWCNTs‐modified EPPG electrode in RTILs and verifying the presence of “defects” on both EPPG and MWCNTs using cyclic voltammograms (CVs) of Fc obtained in RTILs of EMIBF₄, is the main contribution of this preliminary work.     

反胶束模板制备聚甲基丙烯酸甲酯/无机纳米粒子/石墨纳米复合材料及其表征

以甲基丙烯酸甲酯(MMA)和三氯甲烷(CHCl₃)为油相制备反胶束微乳液, 依靠表面活性剂十六烷基三甲基溴化铵(CTAB)自组装形成的“微反应器”作为模板成功地制备了PMMA/Eu(OH)₃/EG和PMMA/Ni(OH)₂/EG纳米复合材料. 并用红外光谱(IR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和差热-热重(TG-DTA)对该复合材料进行了表征和分析. 研究结果表明, 反胶束法可以有效地应用于有机-无机纳米复合材料的制备.     

Effects of EG and MoSi2 on thermal degradation of intumescent coating

An intumescent flame retardant coating was prepared with resin, solvent and flame retardant system composed of ammonium polyphosphate-APP, pentaerythritol-PER and melamine-MEL. The modifiers such as molybdenum disilicide (MoSi₂) and expandable graphite (EG) were used to improve the performances of the APP-PER-MEL coating. The effects of EG, MoSi₂ and MoSi₂/EG on the fireproofing time and char formation of the coating were investigated by using heat insulation test, thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electric microscope (SEM). The results showed that by adding modifiers, the fireproofing time was prolonged and char formation rate was evidently enhanced. The largest improvement was achieved with 9 wt.% MoSi₂/5 wt.% EG, XPS analysis indicated that the performance of anti-oxidation of the coating was improved by adding EG and MoSi₂, and SEM images showed that a good synergistic effect was obtained through a ceramic-like layer produced by MoSi₂ covered on the surface of “open-cellular” structural char.     

元素在石墨炉内石墨探针表面上的原子化机理研究 ⅩⅢ.钼的原子化机理

本文应用x-射线衍射(XRD)、X-射线光电子能谱(XPS)、俄歇电子能谱(AES)、扫描电子显微技术(SEM)研究了钼酸铵在石墨炉内石墨探针表面上的原子化机理。实验结果表明,在温度<1350K时,钼酸铵经历MoO_3和Mo_4O_(11)中间产物转变为MoO_2(s)。在更高温度下,MoO_2(s)首先还原为Mo_2C,而后进一步转变为MoC(s)。MoC再分解为Mo(s)。钼的原子化起源于Mo的升华。     

Enantioseparation of chiral N-imidazole derivatives by electrokinetic chromatography using highly sulfated cyclodextrins: mechanism of enantioselective recognition

Baseline separation of ten new substituted [1-(imidazo-1-yl)-1-phenylmethyl)] benzothiazolinone and benzoxazolinone derivatives, with one chiral center, was achieved by CD-EKC using highly sulfated CDs (alpha, beta, gamma highly S-CDs) as chiral selectors. The influence of the type and concentration of the chiral selectors on the enantioseparations was investigated. The highly S-CDs exhibit a very high enantioselectivity power since they allow excellent enantiomeric resolutions compared to those obtained with the neutral CDs. The enantiomers were resolved with analysis times inferior to 2.5 min and resolution factors R(s) of 3.73, 3.90, 1.40, and 4.35 for compounds 1, 2, 3, and 5, respectively, using 25 mM phosphate buffer at pH 2.5 containing either highly S-alpha-CD, highly S-beta-CD, and highly S-gamma-CD (3 or 4% w/v) at 298 K, with an applied field of 0.30 kV/cm. The determination of the enantiomer migration order for the various analytes and the study of the analyte structure-enantioseparation relationships display the high contribution of the interactions between the analytes phenyl ring and the CDs to the enantiorecognition process. The thermodynamic study of the analyte-CD affinities permits us to improve our knowledge about the enantioseparation mechanism.     

FRS-XRSA表征双轴取向聚对苯二甲酸乙二酯薄膜的取向分布

Ｘ－射线散射理论分析（ＦＲＳ－ＸＲＳＡ）是作者为了研究和表征取向高聚物结晶度与晶粒取向分布（ＯＤＣ）的一种新方案．在表征ＯＤＣ方面应用分峰法（ＣＰＲ）消除了传统极图法（ＰＦＭ）中高重叠峰相互干扰的困难，克服了取向分布函数分析（ＯＤＦＡ）中出现虚织构的困难，并且经一次系统的ＦＲＳ－ＸＲＳ测定，可以得到几乎所有主要（ｈｋｌ）晶面法向的ＯＤＣ．作者应用ＦＲＳ－ＸＲＳＡ对二类双轴取向ＰＥＴ磁带薄膜进行了ＯＤＣ的研究。基于结晶几何学原理（ＣＧＰ），建立了三斜晶系晶粒坐标系与试样坐标系的关系，并用于推演未测定方位角（αｉ，βｉ）（ｈｋｌ）的晶面散射以及未测（ｈ′ｋ′ｌ′）晶面的ＯＤＣ．作者关系建立了双轴取向函数〈ｃｏｓ２φｈｋｌ，ｉ〉，ｉ＝Ｎ、Ｍ、Ｔ的计算公式．按照ＦＲＳ－ＸＲＳＡ获得了反映取向分布的１０个晶面的双轴极图、三个主晶面（１００）、（０１０）、（１０５）的总极图，以及反映平均取向的各种取向函数，如〈ｃｏｓ２φｈｋｌ，ｉ〉、ｆｃｈｋｌ，ｉ等，结果十分令人满意．     

A new dodecylsulfate-selective supported liquid membrane electrode based on its N-cetylpyridinium ion-pair

A supported liquid and a poly(vinyl chloride) (PVC)-based membrane selective for dodecylsulfate (DS⁻) ion are described. The active element is a membrane containing a dissolved ion association complex of DS⁻ with cetylpyridinium (CP⁺) cation. The supported liquid membrane electrode (acetophenone as solvent) showed a Nernstian response towards the DS⁻ anion over the concentration range of sodium dodecylsulfate (SDS) from 8.3×10⁻³ to 1.0×10⁻⁶ mol dm⁻³ at 25 °C. The proposed electrode also showed a super-Nernstian potential response (108±2 mV decade⁻¹) at low concentrations (1.0×10⁻⁹ to 1.0×10⁻⁶ mol dm⁻³). Moreover, this electrode showed good selectivity and precision (R.S.D.?2.0%), and was usable within the pH range 4.0-6.8. The proposed electrode revealed a lower limit of detection of 6.3×10⁻⁷ mol dm⁻³ and improved selectivity in comparison with the some previously reported DS⁻ ion selective electrodes. The isothermal temperature coefficient of this electrode amounted to −0.001 V °C⁻¹. The liquid membrane electrode may find application in the direct determination of SDS by the standard addition method at pH 5.0, and in the physicochemical studies of surfactant solutions.     

Determination of trace metals in industrial boron carbide by solid sampling optical emission spectrometry. Optimization of DC arc excitation (current, atmosphere and chemical modifier)

Graphite arc emission spectrometry has become possible as a result of the invention of novel types of optical spectrometers with Echelle-optics and semiconductor array detectors, and by the application of electronically controlled, high current arc generators. An optimization of the excitation parameters to boron carbide analysis is reported here, measuring background corrected line intensities that were integrated for the time of total evaporation of 5 mg boron carbide sample with or without added chemical modifiers. The following set of experimental conditions were compared with respect of analytical sensitivity and precision: (A) no modifier, Ar + O₂ (20%), 16 A; (B) sample + graphite powder (1 + 1), Ar + O₂ (20%), 16 A; (C) sample + CaF₂ (1 + 1), Ar, 25 A; (D) sample + CaF₂ + graphite powder (1 + 1 + 1), Ar, 25 A. The graphite powder modifier resulted in improved precision in general, and the CaF₂ was effective as a plasma ionization buffer and fluorinating agent. The best compromise was found under conditions B, when oxygen was present in the discharge atmosphere. This is likely due to the stepwise conversion of the boron carbide matrix to the more volatile boron oxide. Under conditions B, detection limits in the ranges of 0.3–9 μg g⁻¹ for Al, Ca, Cr, Cu, Fe, Mg, Mn and Si and that of 18–38 μg g⁻¹ for Ti, W, and Zr were attained. Average RSDs of 10.2 and 9.7% were found, respectively, without and with internal referencing to boron.     

Electrochemical Synthesis of Co-intercalation Compounds in the Graphite-H<Subscript>2</Subscript>SO<Subscript>4</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>System

Anodic oxidation of highly oriented pyrolytic graphite in an electrolyte containing concentrated sulfuric and anhydrous phosphoric acids is studied for the first time. The synthesis was carried out under galvanostatic conditions at a current I = 0.5 mA and an elevated temperature (t = 80°C). Intercalation compounds of graphite (ICG) are shown to form at all concentration ratios of H₂SO₄ and H³PO⁴ acids. The intercalation compound of step I forms in solutions containing more than 80 wt % H₂SO₄, a mixture of compounds of intercalation steps I and II forms in 60% H²SO⁴, intercalation step II is realized in the sulfuric acid concentration range from 10 to 40%, and a mixture of compounds of intercalation steps III and II is formed in 5% H₂SO₄ solutions. The threshold concentration of H₂SO₄ intercalation is ∼2%. With the decrease in active intercalate (H₂SO₄) concentration, the charging curves are gradually smoothed, the intercalation step number increases, and the potentials of ICG formation also increase. As the sulfuric acid concentration in the electrolyte changes from 96 to 40 wt %, the filled-layer thickness d _i in ICG monotonously increases from 0.803 to 0.820 nm, which apparently is associated with the greater size of phosphoric acid molecules. With further increase in H₃PO₄ concentration in solution, d _i remains unchanged. According to the results of chemical analysis, both acids are simultaneously incorporated into the graphite interplanar spacing and their ratio in ICG is determined by the electrolyte composition.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 651–655.Original Russian Text Copyright © 2005 by Leshin, Sorokina, Avdeev.