过渡金属钼钒砷杂多化合物的合成与TPR,TPD研究

Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterized using IR, UV, TG-DTA, pH potential titration techniques. The molecular formulae of these compounds are pro-posed to be H_xM_yAsMO₁₀V₂O₄₀·zH₂O(x=1～3, y=1,2, M=Cr, Mn, Fe, Co, Ni, Cu, Zn).They are all keggin structure. Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reduction techniques. NH₃-TPD results show that in TPD profiles of the compounds there are two desorption peaks corresponding to weak acid sites of desorption, respectively. Desorbing activativon energy and preexponential factor of weak acid site of desorption for compounds have been calculated. H₂-TPR re-sults show that introducting transtion metal to molybdovanarsenic acid, the reduction peak temperatures of H₂-TPR shift regularly with increasing d electron numbers of transition metals. In addition, Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over.     

Thermal coefficient of linear expansion of non-crystalline chalcogenides in the As-S-Se-Te-I system

The object of the paper is an investigation of the glasses of the (As₂S₃)_x(AsSe_0.5Te_0.5I)_100-x. type for 65≤;x≤;95, using methods of thermomechanical analysis. Values of the thermal coefficients of linear expansion in solid and visco-plastic phase were determined. it was shown that introducing arsenic-sulfide in glass-matrix AsChI, i.e. (AsSe_0.5Te_0.5I), leads to an increasing stability of these glasses. The characteristic temperatures of softening Tg and the temperature of the beginning of deformation t_w increase by increasing content of As₂S₃. The analytical forms of dependence of four significant physical values α_g, α_l, Tg, Tw, as a function of As₂S₃ content in the structure of glasses were fitted. This revised version was published online in July 2006 with corrections to the Cover Date.     

高压下C60晶体玻璃化行为的理论研究

通过构造C_(60)分子间的相互作用，研究了在不同压力下C_(60)晶体中的取向有序结构．利用计算出来的两个取向之间的能量差和相隔势驿，研究了热平衡时取向占有几率和玻璃化转变温度的压力相关性．结果与实验符合．     

Thermoanalytical investigation of layered titanium salts

The investigated materials have similar routes of thermal decomposition; i.e. they lose their crystal water first, then at a higher temperature their structural one. At least the result TiP₂O₇ goes through a phase change at about 1000 K. The amorphous titanium phosphate lost its crystal and structural water at higher temperature than those of crystalline forms. Both α- and γ-titanium phosphates and also their transition metal containing forms have layered structure. In case of α- and γ-forms after the loss of crystal water a phase change occurs which is followed by the decomposition of the molecule. Various transition metals containing γ-titanium phosphates lose their crystal water at the same temperature, with the exception of Ni containing ones. The process is finished in this case at temperature 90 K higher than that of the others. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the effect of montmorillonite in the curing reaction of epoxy nanocomposites

The procedure for the fabrication of epoxy-based polymer layered silicate nanocomposites is important in respect of the nanostructure that is developed. To further our understanding of this, the influence of an organically modified clay (montmorillonite, MMT) on the curing kinetics of an epoxy resin has been studied by differential scanning calorimetry. Clay loadings of 10 and 20 mass% are used, and isothermal as well as dynamic cures have been investigated. For both cure schedules the effect of the MMT is to advance the reaction. Kinetic analysis yields values for the activation energy, but shows that the reaction cannot be described simply by the usual autocatalytic equation. The glass transition of the cured nanocomposites is lower than that for the cured neat resin, a result that is attributed to homopolymerisation taking place in addition to the epoxy–amine reaction.     

Synthesis on the basis of electrogenerated carbenes

A series ofS _N2 reactions with halomethanes as substrates and the corresponding anions as nucleophiles were studied by the semiempirical MNDO and AM1 methods, taking into account solvent effects. Analysis of the kinetics, structures of reagents, intermediates and products, and charge distribution in them allows one to draw the conclusion that the retardation ofS _N2 reactions is stronger in solvents than in the gas phase, and the rates of reactions involving anions with a lower number of halogen atoms are higher.For Part 8 see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2148–2154, November, 1995.This work was partially financially supported by the International Science Foundation (Grant No. MHYOO).     

含吩噻嗪金属配合物的合成及非线性光学性质研究

本文报道了一种新的配体:10-乙基-3-甲酰吩噻嗪缩肼基二硫代甲酸甲酯(HL)及其金属配合物的合成。采用了元素分析、质谱、核磁共振、红外光谱对配体及其金属配合物进行了表征。此外,并应用紫外、荧光和Z-扫描技术,测定了配体及其金属配合物的荧光最佳发射波长(λ_max^em)、荧光量子产率(Φ_f)、寿命(τ)和非线性光学性质。结果表明它们在DMF溶液中都能发射出较强的橄榄色荧光,配体及其金属配合物都有双光子吸收,并且金属配合物的非线性光学效应比配体明显增强。用半经验量子化学方法(RHF/PM3)计算结果与实验值较为吻合。     

Study of the Complexation Behavior of Calixarene with Transition Metal Cations by UV—vis and Fluorescent Spectra

A new fluorescent compound based on calix[4] arene skeleton was synthesized.Its complexation ability with transition metal ions,such as Fe^3 ,Co^2 ,Ni^2 ,Cu^2 ,Zn^2 and Ag^ ,Was investigated by UV-vis and fluorescent spectra.     

Thermal analysis of vinyl siding

Vinyl siding is typically produced by co-extruding a capstock (surface layer) over a PVC substrate formulation. The capstock is often non-PVC, these systems can result in warpage during or after production. In our study we will show that this warpage can result from an interfacial induced stress related to the mismatch between the glass transition of the substrate and the capstock. Additionally, both TMA and TMDSC were used to probe the stress release. Capstock formulations which better match the glass transition of the PVC substrate result in superior performance.