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Effect of polymerization conditions on the microstructure of a liquid crystalline copolyester

机译：聚合条件对液晶共聚酯微观结构的影响

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The melt polycondensation of mixtures of sebacic acid (S), 4,4'-diacetoxybiphenyl (B), and 4-acetoxybenzoic acid (H), carried out for the synthesis of semiflexible liquid-crystalline copolyesters referred to as SBH 1 : 1 :x, has been studied with the aim of clarifying the effect of the reaction conditions on the microstructure and the thermal properties of the products. It has been shown that the segregation of a liquid-crystalline phase within the polymerizing mixture, coupled with the thermody namic tendency of the two phases to undergo compositional differentiation as polymerization proceeds, is responsible for the formation of blocky, rather than ideally random, copolyesters with poor processibility, when the mole ratio of H to the other two monomers is higher than x approximate to 1.90. The results of this study have shown that this unwanted effect can be considerably limited by carrying out the polycondensation at a relatively high temperature from the very beginning, rather than by the standard technique involving progressive heating of the reaction mixture, thus allowing the production of SBH copolyesters with a higher degree of aromaticity. The results are discussed in terms of the relative rates of the condensation reactions, which are responsible for chain growth, and of the concurrent acidolysis and esterolysis reactions leading to copolyester sequence reorganization. (C) 2000 John Wiley & Sons, Inc. [References: 21]
机译：癸二酸（S），4,4'-二乙酰氧基联苯（B）和4-乙酰氧基苯甲酸（H）的混合物的熔融缩聚反应，用于合成称为SBH 1：1：1的半柔性液晶共聚酯为了阐明反应条件对产物的微观结构和热性能的影响，已经研究了x。业已表明，液晶混合物在聚合混合物中的偏析，以及随着聚合反应的进行，两相的热成色趋势趋于组成分化，是形成嵌段而不是理想的无规共聚酯的原因。当H与另外两种单体的摩尔比大于x时，可加工性较差，x约为1.90。这项研究的结果表明，通过从一开始就在相对较高的温度下进行缩聚，而不是通过涉及逐步加热反应混合物的标准技术，可以大大限制这种不良反应，从而可以生产SBH具有较高芳香度的共聚酯。根据缩合反应的相对速率（导致链增长）以及导致共聚酯序列重组的同时发生的酸解和酯解反应，对结果进行了讨论。 （C）2000 John Wiley＆Sons，Inc. [参考：21]

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