Analysis of structural relaxation in a Li(2)O2SiO(2) glass using rate heating approach

The structural relaxation process of an inorganic glass (Li(2)O2SiO(2)) at different cooling rates has been studied by differential scanning calorimetry. A four-parameter model-Tool-Narayanaswamy-Moynihan (TNM) model was applied to simulate the normalized specific heat curve measured. Four parameters, Delta h*/R, beta, In A, and x were obtained and compared with the values obtained from the isothermal approach. (C) 1999 Kluwer Academic Publishers.

Polyimides from 3,3 '-dioxo-[1,1 ']-spirodiphthalan-5,5 ',6,6 '-tetracarboxylic dianhydride

A novel dianhydride, 3,3'-dioxo-[1,1']-spirodiphthalan-5,5',6,6'-tetracarboxlic dianhydride, was synthesized and used as a monomer to prepare polyimides with several diamines via a conventional two-stage procedure. The intermediate poly(amic-acid)s had inherent viscosities of 0.84-1.71 dL/g and could be thermally converted into lightly yellow, transparent, flexible and tough films. Films cast from chemically imidized polyimides were transparent and colorless. The glass transition temperatures (Tg) were > 400 degrees C, and the 5% weight-loss temperatures were > 420 degrees C in N-2 and in air. The solubilities of these polyimides in various solvents were evaluated. The mechanical properties of some polyimides were also tested. (C) 1999 Elsevier Science Ltd. All rights reserved.

以水滑石为前体的Mg-Al-M复合氧化物对催化消除NOx的活性

通过H2-TPR，XRD，TG-DTA及比表面积测定等对ＭｇＡｌ水滑石化合物进行了表征，研究了焙烧温度对水滑石物理性质的影响．在此基础上，研究了ＭｇＡｌ水滑石中加入过渡金属（Ｍ）离子后对ＮＯ＋ＣＯ反应的催化活性．结果发现，含有Ｃｕ离子的样品对ＮＯ＋ＣＯ反应有较高的催化活性，并与ＣｏＡｌＭ的催化性能进行了比较

H_8[P_4W_(14)O_(58)Na_4(H_2O)_(20)]·16H_2O的合成、晶体结构与性质

用水热法合成了 H8[P4 W14 O58Na4 (H2 O) 2 0 ]· 16 H2 O,通过 X射线单晶衍射、元素分析和IR进行了结构表征 ,用 TG- DTA研究了热稳定性 .晶体属三斜晶系 ,P1空间群 ,a=1.1379(2 )nm,b=1.36 32 (3) nm,c=1.6 2 71(3) nm;α=78.2 0 (3)°,β=71.2 0 (3)°,γ=71.6 2 (3)°;V=2 .2 52 5(8) nm3 ,Z=1,Mr=4 374 .38,Dc=3.2 2 5mg/ cm3 ,μ=18.0 0 7mm-1,F(0 0 0 ) =1972 ,R=0 .0 74 2 ,Rw=0 .2 0 0 4 .标题化合物的阴离子是由两个 PW7O2 9Na2 (H2 O) 10 亚单元通过与两个磷原子上键合的氧连接而成 ,分子内形成了一个 0 .6 6 14nm× 0 .3189nm的微孔.

HIPS/PP反应共混物的热性能研究

研究了高抗冲聚苯乙烯(HIPS)/聚丙烯(PP)在过氧化二异丙苯(DCP)存在下熔融反应共混物的热学性能。HIPS在DCP存在下以PS的降解为主，PS的Tg明显下降，PP在DCP存在下也以降解为主，PP的结晶完善性受到破坏，HIPS/PP共混物在DCP存在下以PP同HIPS的反应接枝为主，分子运动的特征及热性能较前两者发生明显变化，PS的Tg略有下降，PP分子链的规整性降低，结晶熔点降低，完善性变差。

TiO_2纳米粉的热处理过程研究

用溶胶凝胶法制备出纳米凝胶粉，于不同温度下热处理形成纳米晶，研究热处理温度对粒子大小、形貌、品相转变及吸附能力的关系．XRD、FT-IR、Raman光谱研究表明200～600℃热处理1h的TiO2纳米晶为锐钛矿相，在700℃热处理的纳米晶为锐钛矿相与金红石相共存，800℃热处理的纳米晶完全为金红石相;TEM、TG、XPS的结果证明热处理温度越高，纳米粒子的粒径越大，吸附能力也越弱.

Synthesis and structure of [NH4](4)H[(PMo8V4V2O42)-V-IV-O-V].24H(2)O

[NH4](4)H[(PMo8V4V2O42)-V-IV-O-V] . 24H(2)O has been hydrothermally synthesized from ammonium vanadate and sodium molybdate in aqueous solution by adding phosphorous acid, and its structure determined by single crystal X-ray analysis. The heteropoly molybdovanadophosphate anion is a bicapped 'pseudo-Keggin' polyanion, two vanadium atoms are distributed at two 'capping' metal atom positions and other four vanadium atoms randomly distributed at eight metal atom positions. (C) 1998 Elsevier Science Ltd. All rights reserved.

(NH4)(2)Na-3(V3W3O19).12H(2)O

(NH4)(2)Na-3(V3W3O19).12H(2)O, diammonium trisodium nonadecaoxo(tritungsto)trivanadate dodecahydrate, is a mixed V/W salt in which each site has an approximately equal population of V and W atoms. The centrosymmetric polyanion consists of six (V/W)O-6 edge-sharing distorted octahedra and has a well established structure. Each of the three Na+ cations is surrounded by six water molecules in a distorted octahedron. The (V/W)-O distances are between 1.644(14) and 2.2885 (10) Angstrom.

La_(0.2)Ca_(0.8)MnO_3催化剂活性相的结构和形成机理

利用TG，DTA，XRD和XPS方法研究了La0.2Ca0.8MnO3催化剂的结构和形成机理．样品用La，Ca，Mn混合硝酸盐制备．随着焙烧温度的升高发生了一系列的固相反应，发现氨氧化催化剂催化活性与生成的CaMnO3含量成正比．在900℃制备的含有CaMnO3，La0.575Ca0.425MNO3，Mn2O3和La2O3的混合物是氨氧化最佳催化剂，活性相是CaMnO3，并具有大量的氧空穴.

草酸沉淀法合成LiCoO_2正极材料

用草酸沉淀法合成了LiCoO2，用TG、IR、XRD对合成条件和产物结构进行了研究，结果表明最佳的合成条件是：草酸／CoAc2＝1：1、pH＞6、850℃、8h焙烧，首次充电容量可达140mAh／g以上。

HIPS/PP熔融反应共混及其动态力学性质

研究了高抗冲聚苯乙烯（HIPS）／聚丙烯（PP）共混物在过氧化二异丙苯（DCP）存在下的熔融反应过程及其动态力学性质．HIPS在DCP存在下以聚苯乙烯（PS）的降解为主，伴随着聚丁二烯（PB）的交联和接枝，PP在DCP存在下以降解为主，HIPS／PP在DCP存在下以PP同HIPS的反应接枝为主，这种原位生成的增容剂显著地改善了HIPS／PP两组份间的相容性，其分子运动特征较前两者发生明显变化，PS的Tg下降，PB和PP的Tg升高.

Synthesis and miscibility studies of rodlike flexible polyimide molecular composites via para-para linked aromatic poly(amic ester) precursors

Para-para linked aromatic poly(amic ester) precursors of rodlike polyimide (PI) BPDA-PDA and polyetherimide (PEI) HQDPA-ODA were synthesized. The para-para linked poly(amic ester)s were employed in this work to obtain, in theory, full-imidized polyimides. The two precursors were mixed by dissolving them in N, N'-dimethyl acetamide and subsequently coagulating in methanol. After thermal imidization, the miscibility behaviour of the resulting composites has been studied by means of dynamic mechanical analysis (d.m.a.) and differential scanning calorimetry (d.s.c.). The composites show a single glass transition temperature (T-g) at both d.m.a. and d.s.c. in which the T-g increases with increasing PI content. These Tg values are reproducible in repeated heating cycles, suggesting the true miscibility of the blends. (C) 1997 Elsevier Science Ltd.

The multiple melting behaviour of immiscible poly(ether ether ketone) poly(ether diphenyl ether ketone) blend

Poly(ether ether ketone)/poly(ether diphenyl ether ketone) blend containing 30 wt% PEDEK was used to investigate the melting behaviour of immiscible PEEK/PEDEK blends. The results measured from differential scanning calorimetry (d.s.c.) and wide-angle X-ray diffraction (WAXD) showed that immiscible PEEK/PEDEK blends isothermally crystallized at a temperature between Tg and Tm-2 (PEEK's normal melting point) from the glassy state also exhibited the multi-melting behaviour like poly(aryl ether ketones) homopolymers. In addition, the low-temperature melting peak was independent of composition of poly(aryl ether ketones) blends and only associated with the thermal history. (C) 1997 Elsevier Science Ltd.

The synthesis and thermotropic liquid crystalline behavior of the novel poly(aryl ether ketone)s containing chloro-side group

The novel poly(aryl ether ketone)s containing chloro-side group were synthesized by nucleophilic substitution reactions of 4,4'-biphenol and chlorohydroquinone with either 4,4'-difluorobenzophenone(BP/CH/DF) or 1,4-bis(p-fluorobenzoyl)benzene (BP/CH/BF) and their thermotropic liquid crystalline properties were characterized by a variety of experimental techniques. The thermotropic liquid crystalline behavior was observed in the copolymers containing 50 and 70% biphenol. Melting transition (Tm) and isotropization transition (Ti) both appeared in the DSC thermograms. A banded texture was formed after shearing the sample in the liquid crystalline state. The novel poly(aryl ether ketone)s had relatively higher glass transition temperature (Tg) in the range of 168 similar to 200 degrees C and lower melting temperature (Tm) in the range of 290 similar to 340 degrees C. The thermal stability (Td) was in the range of 430 similar to 490 degrees C.

Preparation, physico-chemical behavior and catalytic property for ammonia oxidation of perovskite like mixed oxides La2-xSrxCuO4-lambda

A series of Sr2+ doped perovskite like oxides La2-xSrxCuO4-lambda (x = 0 similar to 1) were prepared, the structure, lattice parameters, content of Cu3+, oxygen vacancies created by Sr2+ substitution and composition of these complex oxides were studied by XRD and iodic titration method. The redox ability,active oxygen species and surface image were evaluated and analyzed with TPD, TG, XPS and SEM measurements. The catalytic activity for ammonia oxidation over these oxides was tested, and the relationship among the catalytic properties, structure, nonstoichiometric oxygen,redox ability and surface behavior were correlated and some information on the mechanism of ammonia oxidation was obtained.