Effects of molecular weight and interaction parameter on the glass transition temperature of polystyrene mixtures and its blends with polystyrene/poly(2,6-dimethyl-p-phenylene oxide)

The glass transition temperature (T-g) of mixtures of polystyrene (PS) with different molecular weight and of blends of poly(2,6-dimethyl-p-phenylene oxide) (PPO) and polystyrene with different molecular weight (DMWPS) was studied by a DSC method. For the whole range of composition, the curves of T-g vs composition obtained by experiment were compared with predictions from the Fox, Gordon-Taylor, Couchman and Lu-Weiss, equations. It was found that the experimental results were not in agreement with those from the Fox, Gordon-TayIor and Couchman equations for the binary mixtures of DMWPS, where the interaction parameter chi was approximately zero. However, for the blends PPO/DMWPS (chi < 0), with an increase of molecular weight of PS, it was shown that the experimental results fitted well with those obtained from the Couchman, Gordon-Taylor and Fox equations, respectively. Furthermore, the Gordon-Taylor equation was nearly identical to the Lu-Weiss equation when \chi\ was not very large. Further, the dependence of the change of heat capacity associated with the glass transition (Delta C-p) on the molecular weight of PS was investigated and an empirical equation was presented. (C) 1997 Elsevier Science Ltd.

Synthesis, crystal structure and magnetic properties of a series of polymeric lanthanoid-copper complexes [Ln(2)Cu(3){O(CH2-CO2)(2)}(6)].nH(2)O (Ln=La, Nd, n=9; Ln=Er, n=6)

The reaction of diglycolic acid, O(CH2CO2H)(2), with Cu(NO3)(2) . H2O and lanthanoid nitrate hydrate produces a series of novel Ln-Cu mixed metal complexes, [Ln(2)CU(3){O(CH2CO2)(2)}(6)]. nH(2)O (Ln = La, Nd, n = 9; Ln = Er, n = 6), which have been characterized by elemental analysis, i.r. spectroscopy, magnetic measurements and X-ray crystallography. The Ln(3+) and Cu2+ ions are connected by the carboxylate groups of the ligands, resulting in the formation of a complicated network.

PVC-尼龙6树脂应用于天然水中痕量金的价态分析

在王水介质中，ＰＶＣ－尼龙６树脂定量吸附Ａｕ（Ⅲ），而Ａｕ（Ⅰ）基本上不吸附。当存在碘离子时，Ａｕ（Ⅲ）和Ａｕ（Ⅰ）均能形成碘的络阴离子而被树脂定量吸附，从而可分别测出总金和Ａｕ（Ⅲ）的含量并计算出Ａｕ（Ⅰ）的含量。方法的检测限为１．６×１０－１１ｇ／Ｌ，样品加标回收率在８０％以上。为天然水中痕量金的价态分析提供了一个令人满意的方法。

4-羟基偶氮苯与6-氯-5,12-萘并萘醌反应产物的NMR分析

无水碳酸钾存在下6-氯-5,12-萘并萘醌与4-羟基偶氮苯在干燥DMF中反应的主要产物在某些反应条件下不是6[4-(苯基偶氮基)苯氧基]-5,12-萘并萘醌(1)。该未知反应产物2经核磁共振方法研究证实是6-(N,N-二甲氨基)-5,12-萘并萘醌。本文对化合物2的~1H-和~(13)C化学位移、偶合信息和结构作了详细归属,并推测其反应进程,实验结果表明,化合物2是由化合物1与溶剂DMF反应生成。

组成对PA1010/6共聚物熔融行为的影响

用ＤＳＣ研究了ＰＡ１０１０／６共聚物初生态及次生态样品的熔融行为，发现初生态样品的高温熔融峰（Ｔ１）和低温熔融峰（Ｔ２）对组成有不同的依赖关系；首次发现ＰＡ１０１０／６共聚物次生态的冷结晶现象，并讨论了冷结晶温度（ＴＣ）、冷结晶时间（ｔｃ）与组成的关系.

Activation of a ring methyl substituent in pentamethylcyclopentadienyl rhenium(V) compounds: Synthesis and characterization of the 1,2,3,4-tetramethyl-5,6-dihydrofulvene-5,6-dithiolato complex [ReO{(S)(SCH2)C(5)Me(4)}(C(5)Me(5))]

Reaction of the half-sandwich rhenium(v) complexes [Re-Cl-4(C(5)Me(5))] or [Re(O)Cl-2(C(5)Me(5))] with H2S in chloroform in the presence of pyridine leads to the chiral dithiolato complex [ReO((S)(SCH2)C(5)Me(4))(C(5)Me(5))] 1.

Isothermal crystallization studies on neodymium oxide filled nylon 6

Melt mixing of nylon 8 with neodymium oxide particles was carried out with a single-screw extruder. The crystal behaviors of plain nylon 6 and the neodymium oxide filled nylon 6 mixture were studied by means of isothermal crystallization kinetic analysis. Isothermal crystallization thermograms obtained by differential scanning calorimetry (DSC) were analyzed based on the Avrami equation. The neodymium oxide particles acted as a nucleating agent in the mixture. The overall rate of di-isothermal crystallization of the neodymium oxide filled nylon 6 mixture is higher than that of plain nylon 6. The mechanism and modes of plain nylon 6 were the same as those of neodymium oxide filled PA6 mixture.

Electrochemical study of isopoly- and heteropoly-oxometallates film modified microelectrodes .6. Preparation and redox properties of 12-molybdophosphoric acid and 12-molybdosilicic acid modified carbon fiber microelectrodes

The redox behaviours of 12-molybdophosphoric acid (12-MPA) and 12-molybdosilicic acid (12-MSA) in aqueous acid media are characterized at the carbon fiber (CF) microelectrode. The preparation of CF microelectrode modified with 12-MPA or 12-MSA monolayer and the oxidation-reduction properties of the modified electrode in aqueous acid media or 50% (v/v) water-organic media containing some inorganic acids are studied by cyclic voltammetry. 12-MPA or 12-MSA monolayer modified CF microelectrode with high stability and redox reversibility in aqueous acidic media can be prepared by simple dip coating. The cyclic voltammograms of 12-MPA and 12-MSA and their modified CF microelectrodes in aqueous acid solution exhibit three two-electron reversible waves with the same half-wave potentials, which defines that the species adsorbed on the CF electrode surface are 12-MPA and 12-MSA themselves. The acidity of electrolyte solution, the organic solvents in the electrolyte solution, and the scanning potential range strongly influence on the redox behaviours and stability of 12-MPA or 12-MSA monolayer modified electrodes. On the other hand, the catalytic effects of the 12-MPA and 12-MSA and chlorate anions in aqueous acidic solution on the electrode reaction processes of 12-MPA or 12-MSA are described.

尼龙6／SBS共混物形态与性能的研究

尼龙６／ＳＢＳ共混物形态与性能的研究张皓瑜张维广陈长江吕树刚（中国科学院长春应用化学研究所，长春１３００２２）尼龙６是一种重要的大品种工程塑料，在汽车、家电等领域得到了广泛的应用，但由于其吸水率较高，使制品的尺寸稳定性变差，抗疲劳强底低，尤其是冲击韧…

聚氯乙烯-尼龙6树脂分离富集-分光光度法测定痕量金

本文采用聚氯乙烯－尼龙6树脂分离富集溶解于王水中的样品中的痕量金，然后用亚硫酸钠和碘化钾的混合溶液洗脱，并用硫代米酮显色。方法的检测限为1．2×10－9g／g，样品的标准回收为97％～106／，对痕量金样品的分析结果令人满意。

稀土氧化钕填充尼龙6体系的流变行为研究

用锥板粘度仪测试仪测试了稀土氧化钕（Ｎｄ２Ｏ３）填充尼龙６体系的流变行为，填充体系的熔融粘度明显低于空白尼龙６，体系的粘度随稀土氧化物含量的增加而降低，填充后试样具有良好的流动性和加工稳定性。

A STUDY ON THE LUMINESCENCE PROPERTIES OF EU3+ AND DY3+ IN M(2)RE(8)(SIO4)(6)O-2 (M=MG, CA RE=Y, GD, LA)

In this paper, the luminescence properties of Eu3+ and Dy3+ in the oxyapatites M(2)RE(8)(SiO4)(6)O-2 (M=Mg, Ca; RE=Y, Gd, La) were studied. The spectral characters of Eu3+ were discussed in relation to the crystal structure. The dependence of the red-to-orange intensity ratio and the position of the charge transfer band of Eu3+ and the yellow-to-blue intensity ratio of Dy3+ together with their fluorescence intensities (I-R for Eu3+ and I-Y for Dy3+) On the M(2+) and the substitution of BO45- and PO43- for SiO44- was discussed. Finally, the concentration quenching of Dy3+ luminescence was reported.

LUMINESCENCE AND ENERGY-TRANSFER OF RARE-EARTH-METAL IONS IN MG2Y8(SIO4)(6)O-2

The photoluminescence of Ce3+, Tb3+ and Sm3+, and energy transfer from Ce3+ to Tb3+, Dy3+ and Sm3+ in Mg2Y8(SiOd(4))(6)O-2 are reported and discussed. The Ce3+ ion shows blue luminescence under UV excitation, and occupies simultaneously the 4f site and 6h site in the host lattice. The optimum concentrations for the D-5(3) and D-5(4) emissions of Tb3+ and the (4)G(5/2) emission of Sm3+ are determined to be 0.04, 0.20 and 0.10 mol in every mol of Mg2Y8(SiO4)(6)O-2, respectively. The critical distances responsible for the cross-relaxation between the D-5(3)-D-5(4) and F-7(6)-F-7(0) transitions of Tb3+ and between the (4)G(5/2)-F-4(9/2) and H-6(5/2)-F-4(9/2) transitions of Sm3+ are estimated to be 1.43 and 1.06 nm, respectively. Both Tb3+ and Dy3+ can be sensitized by Ce3+, but Ce3+ and Sm3+ quench each other.

POLYMERIZATION OF ACRYLONITRILE INITIATED BY DI(2,6-DI-TERT-BUTYL-4-METHYLPHENOXO) SAMARIUM COMPLEX

The polymerization of acrylonitrile initiated by organolanthanide complexes alone is studied for the first time. The effect df polymerization conditions on catalytic activity of the title complex and molecular weight of the polymers produced have been studied.

COMPARATIVE-STUDY OF CA4Y6(SIO4)(6)O-A PHOSPHORS PREPARED BY SOL-GEL AND DRY METHODS (A=PB2+,EU3+, TB3+,DY3+)

Ca4Y6(SiO4)(6)O:A (A = Pb2+, Eu3+, Tb3+, Dy3+) phosphors have been prepared by two methods: the sol-gel method and the conventional dry method. The crystallization processes and the luminescence characteristics of the phosphors were studied, The sol-gel method features low-temperature formation of the phosphor, leading to successful preparation of Pb2+-activated phosphors which could not be prepared by the dry method at high temperature. The (4f)(8-)(4f)(7)(5d)(1) absorption band of Tb3+ and the charge-transfer (CT) band of Eu3+ have higher energies and narrower half-widths in the sol-gel-derived phosphors than in the phosphors prepared by the dry method, respectively. The Tb3+ and Dy3+ ions show stronger emission in the former than in the latter. Both the yellow-to-blue intensity ratio (Y:B) of Dy3+ and the red-to-orange intensity ratio (R:O) of Eu3+ in the sol-gel-derived phosphors are smaller than those for the phosphors derived by the dry method.