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首页> 外文期刊>High performance polymers >Synthesis and Characterization of Aromatic Polyamides Obtained from 4-4'-(9-fluorenylidene) diamine, 4-4'-(hexafluoro-isopropylidene) dianiline and 4-4'-diamine-benzophenone
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Synthesis and Characterization of Aromatic Polyamides Obtained from 4-4'-(9-fluorenylidene) diamine, 4-4'-(hexafluoro-isopropylidene) dianiline and 4-4'-diamine-benzophenone

机译：由4-4'-（9-芴基）二胺，4-4'-（六氟-异亚丙基）二苯胺和4-4'-二胺-二苯甲酮制得的芳族聚酰胺的合成与表征

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Nine aromatic polyamides were synthesized from three different diamines by high-temperature polycondensation using three different aromatic diacid chlorides. A comparison of the effect that structural modifications afforded by the substitutions at the diacid chloride phenyl position and the introduction of bulky side groups in the diamine contribution were evaluated. Polyamide properties were characterized by DSC, TGA, wide angle x-ray scattering, density, light scattering and solubility. Differential scanning calorimetry measurements indicated that all polymers have high glass transition temperatures ranging from 236 to 319 ℃, while thermogravimetrical measurements show that the onset of decomposition of these polymers is above 460 ℃ and that they are thermally stable. It was also found that almost all polymers were soluble in polar aprotic solvents. The results indicate that introduction of bulky side groups in the structure of the aromatic polyamides increases the T_g, while packing efficiency is lowered by these aromatic groups. Furthermore, the hexafluoro substitution in the polyamides raises their thermal stability, which may be attributed to the strong C-F bond. A relationship between T_g and the conformational entropy determined by structure was found, indicating that the higher the rigidity of the polyamide the higher the T_g. Moreover, the incorporation of bulky side groups on the structure increases the T_g more than an increase on rigidity, which indicates that the effect of intermolecular interactions is more important for an increase in T_g than the effect of chain stiffness.
机译：通过使用三种不同的芳族二酰氯通过高温缩聚反应，由三种不同的二胺合成九种芳族聚酰胺。评价了在二酰氯苯基位置上的取代和在二胺贡献中引入大体积侧基的结构修饰的效果的比较。通过DSC，TGA，广角X射线散射，密度，光散射和溶解度来表征聚酰胺性能。差示扫描量热法测量表明，所有聚合物均具有较高的玻璃化转变温度，范围为236至319℃，而热失重测量表明，这些聚合物的分解开始高于460℃，并且它们是热稳定的。还发现几乎所有的聚合物都可溶于极性非质子溶剂。结果表明，在芳族聚酰胺的结构中引入大体积侧基增加了T_g，而这些芳族基团降低了填充效率。此外，聚酰胺中的六氟取代提高了其热稳定性，这可能归因于强C-F键。发现T_g与由结构确定的构象熵之间的关系，表明聚酰胺的刚性越高，则T_g越高。此外，在结构上掺入大体积侧基增加的T_g大于刚性的增加，这表明分子间相互作用的影响比链刚性的影响对T_g的增加更重要。

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