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为制备液晶聚芳酯,本文用DSC研究二元芳酰氯与二元酚的熔融缩聚反应。测得芳酰氯与邻氯对苯二酚反应的温区均在芳酰氯的熔点附近。并观察到当2.6-萘二甲酰基占大分子链中芳酰基总量的40%以下时,聚芳酯熔点较低;反之,熔点明显上升。于200℃、N_2保护下常量合成了一系列主链结构不同的全芳香型聚酯。讨论了单体结构和配比对聚芳酯液晶性的影响。对结构为的聚芳酯进行了分析和表征:Cl含量、IR、TG、DSC和热台偏光显微摄象的测试结果,表明该聚酯有如下特性: (1)T_g=155℃,T_m=180℃,T_n=310℃(向列型液晶态转变温度)。(2)在310—460℃范围内呈热致性向列型液晶态而不存在各向同性转变(T_i),其T_i>T_d。
In order to prepare the liquid crystalline polyarylate, DSC was used to study the melt polycondensation of diaryl aromatics and dihydric phenols. The aromatics and o-chlor hydroquinone were measured in the vicinity of the melting point of aroyl chloride. It was observed that the melting point of polyarylate was lower when 2.6-naphthalene dicarboxylic acid accounted for less than 40% of the total amount of aroyl groups in macromolecule chain. On the contrary, the melting point increased obviously. A series of all aromatic polyesters with different main chain structures were synthesized at 200 ℃ under N2. The effect of monomer structure and ratio on the liquid crystallinity of polyarylate was discussed. The structure of the polyarylate was analyzed and characterized. The results of the Cl content, IR, TG, DSC and hot bench polarization microscopy showed that the polyester had the following properties: (1) T_g = 155 ℃, T_m = 180 ° C, T_n = 310 ° C (nematic liquid crystal transition temperature). (2) In the range of 310-460 ℃, it has a thermotropic nematic liquid crystal state without isotropic transition (T_i), which is T_i> T_d.