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首页> 外文期刊>Journal of Applied Polymer Science >Structure and properties of fully aromatic thermotropic liquid-crystalline copolyesters containing m-hydroxybenzoic acid units
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Structure and properties of fully aromatic thermotropic liquid-crystalline copolyesters containing m-hydroxybenzoic acid units

机译：含间羟基苯甲酸单元的全芳族热致液晶共聚酯的结构和性能

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摘要

A series of fully aromatic copolyesters based on p-acetoxybenzoic acid (p-ABA), hydroquinone diacetate (HQDA), terephthalic acid (TPA), and m-acetoxybenzoic acid (m-ABA) were prepared by a modified melt-polycondensation reaction. The copolyesters were prepared in two series in which series I is based on a two monomer system (p-ABA/m-ABA) and series II is based on a three monomer system (HQDA/TPA/m-ABA). The effect of different linear structures and kink moiety on the properties of the copolyesters were investigated systematically. The copolyesters were characterized by differential scanning calorimetry, thermogravimetric analysis, H-1-NMR, polarized optical microscopy, X-ray diffraction, and intrinsic viscosity measurements. It was found that the copolyesters exhibited nematic liquid-crystalline phases when the content of linear (p-ABA or HQDA/TPA) units was over 67 mol %. The melting or flow-transition temperatures were decreased with an increase of the content of kink m-ABA units. The copolyesters that contained p-ABA as linear units had a significantly higher degree of crystallinity compared to the copolyesters that contain HQDA/TPA as the linear units, implying a higher blockiness in the polymer chains as a result of the higher reactivity of the p-ABA units in the p-ABA/m-ABA system. All the copolyesters had poor solubility except the copolyesters containing at least 40 mol % of m-ABA, which were soluble in a dichloromethane/trifloroacetic acid (70:30 v/v) mixture. (C) 2003 Wiley Periodicals, Inc. [References: 26]
机译：通过改进的熔融缩聚反应，制备了一系列基于对乙酰氧基苯甲酸（p-ABA），对苯二酚氢乙酸酯（HQDA），对苯二甲酸（TPA）和间乙酰氧基苯甲酸（m-ABA）的全芳族共聚酯。共聚酯按两个系列制备，其中系列I基于两种单体体系（p-ABA / m-ABA），系列II基于三单体体系（HQDA / TPA / m-ABA）。系统地研究了不同的线性结构和扭结部分对共聚酯性能的影响。通过差示扫描量热法，热重分析，H-1-NMR，偏振光学显微镜，X射线衍射和特性粘度测量来表征共聚酯。发现当线性（p-ABA或HQDA / TPA）单元的含量超过67mol％时，共聚酯表现出向列型液晶相。随着扭结m-ABA单元含量的增加，熔融或流动转变温度降低。与包含HQDA / TPA作为线性单元的共聚酯相比，包含p-ABA作为线性单元的共聚酯具有更高的结晶度，这表明由于p-ABA的较高反应性，聚合物链中的嵌段性更高。 p-ABA / m-ABA系统中的ABA单位。除了含有至少40mol％的m-ABA的共聚酯之外，所有共聚酯的溶解性均较差，它们可溶于二氯甲烷/三氟乙酸（70:30 v / v）的混合物中。 （C）2003 Wiley Periodicals，Inc. [参考：26]

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