聚合物微晶尺寸和晶格畸变

聚合物微晶尺寸和晶格畸变是对聚合物材料性能有着重要影响的结构参数。本文介绍了应用Ｘ射线衍射方法测定聚合物微晶尺寸和结构畸变的几种方法：近似函数、次晶模型法、方差法、矩法。     

Ability of porous graphitic carbon to support electroosmotic flow in capillary electrochromatography

The existence of a cathodic EOF (electroosmotic flow) in the case of a porous graphitic carbon (PGC) partially packed column has been demonstrated. Then, the ability of PGC to afford electroosmosis has been brought to the fore with a fully PGC packed column. Experimental data have shown that PGC particles are negatively charged and their electrophoretic mobility has been evaluated. In order to investigate the conditions of existence of EOF different mobile phases have been tested. An EOF occurs when the conductivity of the PGC packed column is larger than the conductivity of an empty fused-silica capillary operating in the same conditions i.e. when the PGC participates in the electric conduction. Since the local electric fields in the two segments of the column are different, an evaluation of the electroosmotic mobility is not possible and the effect of the operational parameters such as the composition of the mobile phase (acetonitrile ratio and total ionic strength) has been studied in term of electroosmotic velocity V(eo).     

PEO／PVP共混体系结晶行为

本文用WAXD、PLM、DSC方法研究了聚氧化乙烯(PEO)/聚乙烯基吡咯烷酮(PVP)共混体系的结晶行为,探索了两组分聚合物间相互作用及体系结晶度与非晶组分含量的关系。DSC研究表明PEO/PVP共混体系具有两个玻璃化转变温度,分别是纯组分的T_g,无相容性。应用Avrami和LH方程对其动力学参数进行了研究。偏光显微镜观察了共混物结构形态。     

DETERMINATION OF DEGREE OF CRYSTALLINITY OF NYLON 1212 BY WIDE-ANGLE X-RAY DIFFRACTION

Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.     

热处理对Nylon—11结构的影响

对不同温度热处理过的Nylon－11样品，采用广角X射线衍射（WAXD），根据X射线衍射强度理论，用多重峰图解分峰方法研究了Nylon－11结构的变化，并导出了计算Nylon－11结晶度的公式．所得结果与密度法、DSC法进行了比较．同时也给出了Nylon－11的有关热力学参数，     

用WAXD和SAXS研究辐照聚酰胺1010结构

用ＷＡＸＤ和ＳＡＸＳ方法研究了聚酰胺１０１０的聚集态结构和结晶结构的辐射损伤过程和机理。辐射交联与裂解主要在非晶区和结晶表面或中间相发生；辐射损伤并从这里开始，随辐射剂量增大，非晶化逐渐向晶区伸展，有氢键的（０１０）晶面损伤几率高于（１００）晶面；辐射后效应导致新的交联与裂解生成，主要影响（０１０）晶面的形成与完善，使Ｌ１００及Ｗｃ变小。     

A kinetic study of methane conversion by a dinitrogen microwave plasma

Conversion of CH₄ with a N₂ microwave plasma (2.45 GHz) is studied. The experiments cover the absorbed microwave power range 300–700 W with 17–62% of methane in the gas mixture, with pressures of 10–40 mbar and flow rates of 140–650 ml· min^–1. The yields of C₂ hydrocarbons and dihydrogen are analyzed by gas chromatography. The distance of methane addition downstream of the plasma plays an important role on the composition and the concentration of the products obtained. This distance mainly determines the energy concentrated in the active species of the plasma when they react with methane. Different behaviors for acetylene formation, on the one hand, and for ethane and ethene formation, on the other hand, have been observed, and this finding allows us to propose a kinetic mechanism for the decay of methane and for the formation of C₂ hydrocarbons.     

Etude de la structure de l'iodatochromate de potassium par spectrographie d'absorption infrarouge entre 3 et 35μ

Résumé Dans le spectre d'absorption infrarouge de l'iodatochromate de potassium K[(CrO₃)(IO₃)], on peut identifier la présence de bandes de vibration de valence de ponts Cr-0-I à 508 et680 cm^–1.

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Summary The infrared absorption spectrum of potassium iodatochromate K(CrO₃)(IO₃) contains vibration bands of the valence bridges Cr-O-I at 508 and 680 cm^–1.

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Zusammenfassung Im Infrarot-Absorptionsspektrum des Kaliumjodatochromats lassen sich Banden der Valenzschwingungen der Atomgruppe Or-O-J bei 508 und 680 cm^–1 nachweisen.

     

Electrical conductance of CHCl3 solutions of polyethylene oxide doped with KCI

CHCl3 solutions containing a few percent polyethylene oxide PEO (M_W = 200 000) or the low-molecular model dioxane are stirred at 50°C during more than 100 h in the presence of small amounts of KCl. The specific conductance, the viscosity and the density of the solutions are measured at 25°C as a function of time. Both PEO and dioxane act as ligands improving the solubility of KCl. The relaxation times are of the order of several hours. After 40 h or more the viscosity of the solutions increases in a spectacular way. However, the most striking observation is that the specific conductance of the polymeric solutions at 25°C is systematically 5% higher than the value measured with the same sample at 45°C, just as for metals. The effect of the dilution of the primary stirred solutions either in the pure solvent or in the initial polymer solution is investigated. These results are discussed in terms of a three-step mechanism in the polymer systems: (1) Loading of the coils to polymeric cations with a full elementary charge, as a consequence of charge transfer interactions of the crown-ether type with numerous K⁺ ions penetrating into the coils; (2) Electron tunnelling conduction of the Hamill—Ceulemans type from one positive coil to the neighbouring one; (3) Alteration of the structure of the coils and of their hydrodynamic radius by the motions of K⁺ in the coils. These ‘brachiation’ motions by a hopping mechanism result from an increased mobility of the complexed K⁺ ions, which is also the origin of the Zundel effect. They do not directly contribute to the conductance but are responsible for the delayed increase of the viscosity.     

Smith－Hieftje背景校正法空心阴极灯供电条件的选择

本文提出在原子吸收光谱测定中，采用Ｓｍｉｔｈ－Ｈｉｅｆｔｊｅ法校正背景时，空心阴极灯供电条件（即最佳宽窄脉冲电流）的选择依据和选择方法；并给出２４个常见元素的宽窄脉冲电流的选定结果。