聚酯聚醚嵌段共聚物与1,4-二咔唑环丁烷在激发态及基态的相互作用

<正> 聚酯聚醚嵌段共聚物具有十分良好的物理和机械性能,能加工成橡胶、纤维、塑料胶粘剂等,近年来也有作为医用高分子材料的报道。所以对聚酯聚醚嵌段共聚物的研究十分活跃。然而,有关其光物理性质的研究还很少见。本文报道了混合聚醚-聚酯嵌段共聚物(MPEE)与反式1,4-二咔唑环丁烷(1,4-DCC)在激发态和基态下的相互络合作用。结果表明,MPEE可以猝灭1,4-DCC的荧光,同时形成激基复合物。在分散     

Synthesis and characterization of segmented liquid crystal poly(azoxy polyester-co-polyoxypropylene)

In this study a series of a segmented copolyester, poly(4,4′-dioxy-2,2′-dimethyl-azoxybenzene dodecanedioyl) (PMABD)-co-polyoxypropylene 400 (POP), was prepared. The chain length of PMABD studied (n) was varied from 7.8-18.2, and that of POP was unchanged. The intrinsic viscosity of the segmented copolyesters was 1.04-1.30, and the number average molecular weight obtained was 2.53 × 10⁴?3.49 × 10⁴ g/mol. The mesophase texture and thermal properties of the segmented copolyesters were measured as functions of n. It was found that the insert of flexible POP between those liquid crystalline domains of PMABD did affect thermotropic properties of PMABD. As the n value was 9.0 and 7.8 (or 7.4 and 8.6% by weight POP) the texture appeared as cholesteric-like oily streaks. The effect could not be attained by simply copolymerizing a mesogenic moiety with a pair of spacers of different lengths. The fluidity and domain structure of the flexible dodecanedioyl-POP-dodcanedioyl segments are taken into account for the obtained results. © 1995 John Wiley & Sons, Inc.     

主链含硅聚芳酯的合成及气体透过性能的研究

以双［对－酰氯苯基］二甲基硅烷和酚酞、四溴酚酞以及双酚Ａ为原料，合成了三种主链含硅聚芳酯，并对聚合物相关的物理性质进行了表征，制成了均质透明的薄膜．采用低真空法测定这些聚合物对Ｈ２、Ｏ２、Ｎ２、ＣＯ２、ＣＨ４的气体透过速率，并计算出气体透过系数、扩散系数、溶解系数、分离系数．从气体透过性能与聚合物分子结构关系的角度，按照气体透过的溶解－扩散机制，对聚合物的气体透过性能进行了研究，而且着重讨论了聚合物的堆积密度对气体扩散系数的影响，以及聚合物主链中极性链段的百分含量对气体溶解系数和溶解选择性的影响。     

A novel hyperbranched polyester acrylate used for microfabrications

A novel hyperbranched polyester acrylate (HPEA) was synthesized based upon ethylenediamine tetraacetic acid as a “core” molecule, 5‐hydroxyisophthalic acid as an AB₂ monomer, and 2‐hydroxyethyl acrylate as an endcapping reagent. The obtained oligomer has an unsaturation concentration of 4.10 mmol_C?C g^?1 measured by nuclear magnetic resonance and a wide molecular weight distribution of 1.64 measured by gel permeation chromatography. The two‐photon absorption (TPA) photopolymerization of HPEA under the exposure of a Ti : sapphire femtosecond laser with a wavelength of 800 nm was investigated through laser exposure dose‐dependant spatial resolutions of its resins. The TPA photopolymerization thresholds at the range 1.6–4.3 × 10⁷ mJ cm^?2, and exposure dose windows at the range 3.4–4.3 for three formulations were determined. A spatial resolution of 0.85 μm was obtained through the TPA photopolymerization of the formulation containing 1 wt% photoinitiator and 0.3 wt% photoinhibitor. A diffraction grating and real three‐dimensional coupled gear wheel created by TPA photopolymerization were described to demonstrate the unique capability of HPEA in microfabrications. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrosynthesis of hafnium diboride from cryolite-alumina melts containing hafnium and boron oxides

Electrosynthesis of hafnium diboride from cryolite-alumina melts containing hafnium and boron oxides is studied. Thermodynamic estimation and voltammetric measurements show this process to occur in one-stage. Hafnium diboride coatings on nickel are obtained by electrolysis.__________Translated from Elektrokhimiya, Vol. 41, No. 4, 2005, pp. 448–451.Original Russian Text Copyright © 2005 by Devyatkin.     

考虑壁面滑移的Z-W流变模型及其应用

总结了聚合物熔体在剪切溶场壁面滑移研究的成果，提出了Z－W模型的物理概念。该模型考虑了界面分子链和固体壁面间解吸－吸附而发生的滑移。界面分子链和内部分子链间解缠－重新缠结而发生的表观滑移以及变形摩擦滑移。在稳态简单剪切流运过程，模型可以化简为应力和应变的二次微分方程，说明了壁面滑移来源于Cohesive滑移和Adhesive滑移两部分，对于自激振荡相关的多重内振荡和多重外振荡进行了归纳，应用统一模型定性地解释了毛细管实验中剪切应力的非线性，瞬态自激振荡、滑－粘转换和鲨鱼皮等现象，在聚合物熔体振动剪切流动（LAOS）中，统一模型可以简化为杜芬方程，通过模拟发现，该模型可解释小应变振幅下振动剪切时的线性流变行为和在大振幅振动流动中的复杂非线性行为。非线性行为与熔体粘弹性以及近壁面界面层的性质有关，统一模型在特殊情况下还可以简化Joshi模型，结构网络模型，Hatzikiriakos或等效的Graham模型，可见，Z－W模型内内涵比较丰富，适用面较广，也从一个侧面说明该模型具有相当的合理性。     

聚碳酸酯改性聚酯型热塑性聚氨酯弹性体的合成与性能

以聚碳酸１，６－已二醇酯（ＰＣ）、聚己二酸－１，４－丁二醇酯（ＰＢＡＧ）、４，４－二苯基甲烷二异氰酸酯（ＭＤＩ）和１，４－丁二醇（ＢＤＯ）为原料，合成线型聚碳酸酯改性聚酯型热塑性聚氨酯弹性体（ＴＰＣＺＥ）．对其玻璃化转变温度Ｔｇ、力学性能、耐水解性能和流变特性进行了研究。实验结果表明：随ＰＣ二醇含量的增加，弹性体的贮能模量下降，Ｔｇ则向高温方向（从－７．８℃到＋２．６℃）移动。水解后的强度保持率从８５．４％提高到９９，７％和１１７％，熔体的表现粘度降低，加工性能得到改善。     

Self-ordering process of phenanthrene polyesters observed by the simultaneous DSC-XRD method

Phase transition behavior of polyesters derived from 2,7-phenanthrene dicarbonic acid diethylester and alkanediols with even methylene carbon number was investigated by the simultaneous DSC-XRD method. The smectic A phase was observed on cooling from the molten state. The transition entropy from the isotropic state to the smectic A phase was about 9.0 J mol^-1 K^-1, which depended on the methylene carbon number. The linear expansion coefficients, based on the (001) spacing of the crystalline phase at room temperature, were 1.3·10^-4 K^-1 (crystalline phase), 5.7·10^-4 K^-1 (crystallization region), 1.7·10^-3 K^-1 (smectic A phase) during cooling, and 1.5·10^-4 K^-1 (crystalline phase), and 1.0·10^-3K^-1(melting region) on heating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solubilities,thermostabilities and flame retardance behaviour of phosphorus-containing flame retardants and copolymers

Thirteen phosphorus-containing flame retardants were synthesized in this work. The solubilities of flame retardant [(6-oxide-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)-methyl]-butanedioic acid (DDP) in selected solvents are measured. TGA measurements of the 13 phosphorus-containing flame retardants were carried out and thermal stabilities of three flame-resistant PET (FRPET) resins were investigated. A FRPET incorporated by DDP with terephthalic acid and ethylene glycol reported in literature was also discussed and compared. The thermal stability of the FRPET is improved by the incorporation of phosphorus-containing flame retardants. The LOI values of all phosphorus-containing polyesters are higher than 27%. The improvement of the flame-resistant ability is due to the formation of the char that is not only caused by the existence of phosphorus elements in the resin but also by the relative large number of carbon atoms of the phenyl group in the flame retardants.     

甲烷氧化偶联Na2WO4-Mn/SiO2催化剂热效应的研究

采用固定床微型反应装置,研究了甲烷氧化偶联反应过程中Na2WO4-Mn/S iO2催化剂床层的热效应和催化性能的关系,考察了反应炉温、CH4/O2比和反应气体空速对催化剂床层热点分布的影响.研究结果表明,甲烷氧化偶联催化剂床层的热效应强烈依赖于反应条件.反应炉温越高,CH4/O2比越低,反应气体空速越大,催化剂床层的热点温度越高.结合催化性能和热效应关系的研究,为优化甲烷氧化偶联的反应操作提供了实验依据.