Synthesis and properties of a novel perfluorononenyloxy group containing polyarylates

A series of novel perfluorononenyloxy group containing polyarylates were synthesized by a high-temperature solution condensation of 5-(perfluorononenyloxy)-isophthaloyl chloride ( II ) with various aromatic diols in o-dichlorobenzene. All the polyarylates were amorphous and readily soluble in many organic solvents such as o-chlorophenol, o-dichlorobenzene, chloroform, and polar aprotic solvents at room temperature or on heating. Transparent, tough, and flexible films of these polymers could be cast from the o-chlorophenol solutions. The polymers having inherent viscosity of 0.61–1.63 dL/g were obtained in quantitative yields. These polymers were thermally quite stable. The glass transition temperatures of these polyarylates were in the range of 219–242°C by DSC and 224–251°C by DMA, and the 10% weight loss temperatures in nitrogen and air were above 415 and 397°C, respectively. Moreover, these polymers maintained good mechanical properties (G′ ∼ 10⁸ Pa) up to 220°C and had lower moisture absorption than common polyarylates. The dielectric constants of these polymers ranged from 3.23 to 3.75. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 645–653, 1998     

Preparation and characterization of fluorine-containing aromatic condensation polymers. VI. Aromatic polybenzothiazoles from 4,4′-(hexafluoroisopropylidene)dibenzoic acid and tetrafluoroterephthalic acid and 2,5-diamino-1,4-benzenedithiol dihydrochloride

Two fluorine-containing aromatic polybenzothiazoles were synthesized by direct polycondensation of 4,4′-(hexafluoroisopropylidene)dibenzoic acid and tetrafluoroterephthalic acid with 2,5-diamino-1,4-benzenedithiol dihydrochloride using phosphorus pentoxide/methanesulfonic acid or polyphosphoric acid as both condensing agent and solvent. The effect of introduction of fluorine atom on the synthesis and properties of these polymers was discussed in detail. The perfluoroisopropylidene unit-containing polybenzothiazole was amorphous, and showed good solubility in organic solvents, excellent mechanical properties, and high thermal stability. The perfluoro-p-phenylene unit-containing polybenzothiazole was crystalline, and exhibited lyotropic behavior in concentrated sulfuric acid. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 429–435, 1998     

铝基矿物在钙基固硫过程中的固相反应机理分析

在高温电阻炉中对高硫煤掺入钙铝基添加剂后进行燃烧试验,分析了不同条件下煤中加入添加剂后固硫效率、固硫灰渣的矿物组成及微观形貌的变化特性;综合采用TG-FTIR-XRD研究了化学纯矿物CaO-A12O3-CaSO4体系中硫酸钙的高温热分解过程及产物组成.结果表明,A12O3的加入通过固相反应来影响钙基固硫效率,A12O3对固硫效率的影响并非呈单一性;低温下生成Ca-Al酸盐矿物削弱了固硫反应,而高温下CaSO4与灰中生成的含Ca、Al类矿物反应形成高温固硫物相硫铝酸钙并抑制其分解则提高了钙基固硫效率.     

早期高温强碱环境下转炉钢渣的长龄期水化特性

使用具有微弱自身水硬性的转炉钢渣制备了"无熟料"胶凝材料,改变早期水化环境,并通过压汞法和扫描电子显微镜测试了长龄期(10年)后钢渣体系硬化浆体的孔结构和微观形貌,研究了早期高温强碱环境对于钢渣长龄期水化的影响.结果显示:早期高温强碱环境对钢渣体系的后期孔结构产生不利影响;早期高温强碱环境并不影响凝胶产物的种类,产物都...     

可见光作用下LaTaON2催化剂光催化分解水制氢

 采用高温氮化技术,以氯化铵为矿化剂合成了层状钙钛矿型LaTaON2光催化剂. 与前驱体氧化物LaTaO4相比, LaTaON2的吸收边红移,在可见区呈现较强的吸收. 在可见光作用下,乙醇为牺牲剂时,同时负载Pt和Ru的LaTaON2能催化分解水放出H2, 且其光催化产氢效率大大高于单独负载Pt或Ru的LaTaON2催化剂.     

SOI高温器件及其在汽车电子等领域中的应用

石油钻井,航空航天,汽车等工业领域急需在高温下工作的器件和电路。ＳＯＩ技术在高温器件和电路方面有着广泛的应用前景。文章简要介绍了ＳＯＩ技术应用于制造高温器件和电路方面的进展情况。     

Study of Pseudogap in Underdoped Cuprate

A mean-field spin-density wave (SDW) analysis of pseudogap in the underdoped cuprates is proposed on the dependence of the energy gap which mimics the pseudogap near (π, 0) point at least. It implies that the pseudogap structure near (π, 0) is not sensitive to the long-range order and will survive leading to the pseudogap phenomenon in the underdoped metallic phase. On the other hand, in the long-range ordering antiferromagnetic region, the mean-field SDW theory holds and the pseudogap structure predicated by the theory should be observable experimentallyv. Then one prediction is that the pseudogap would smoothly extrapolate between itinerant antiferromagnetic phase and underdoped metallic phase.     

氧化物高温超导体Tc与内层轨道关联的关系研究

通过研究7大类40多个铜氧化物超导体系中Cu-O面最近邻阳离子(A)，我们发现了一个重要的规律——所有的A的内层p能级都与O的内层2s能级(-29．16eV)非常接近，分布在从-22．85～-3_4．80eV之间的一个窄小的区域内，而且此区域内没有任何非超导原子的p能级．详细的电子结构计算表明，所有的A的次内层p轨道都与Cu-O面上的O的内层2s轨道之间存在着轨道耦合关联，而且内层的关联强度与该体系的最高临界温度(Tc)成正比，关联强度越大，瓦越高．因此我们认为：A与O间的内层轨道耦合是高温超导现象产生的主要原因．     

压电陶瓷高温极化机理研究

介绍了压电陶瓷高温极化机理，通过电畴的形成及顺电铁电相变机理对其进行了解释。     

Fundamentals, achievements, and perspectives for development of solid-flame combustion

The review is devoted to the problem of self-propagating high-temperature synthesis (SHS). The fundamentals of SHS are briefly considered, the most promising results of the experimental diagnostics and modeling of SHS processes are presented, new nonlinear phenomena and the data of thermodynamic calculations, as well as kinetic and macrokinetic studies are discussed. The main types of the SHS technology and their application for the preparation of new compounds, materials, and items along with technical and economical effectiveness are considered. New directions and perspectives of SHS are discussed. The review was prepared from materials of the author's report in the Session of the Presidium of the Russian Academy of Sciences in May, 1996. (Translated by E. Batova.) Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 8–32. January, 1997.