Aliphatic polyamides (nylons) show a remarkable variability in terms of crystallographic structures, polymorphic transitions and crystal morphology despite all polymers of this family have a simple constitution that is based on amide groups and polymethylene segments. Nylons derived from diamines and dicarboxylic acids having different parity (e.g., even or odd) have peculiar characteristics due to the difficulty of establishing an optimal hydrogen-bonding geometry when molecular chains adopt a typical all trans conformation. In this work, two isomeric odd-even (nylon 7,10) and even-odd (nylon 10,7) polyamides with the same methylene/amide ratio have been studied. Specifically, crystallization kinetics have been evaluated from calorimetric data, while thermal degradation mechanisms from thermogravimetric analysis. Classical methods (e.g., Avrami) together with isoconversional analyses have been considered for crystallization studies, being found significant differences between both nylons in terms of nucleation and activation energies. The isoconversional analyses of the non-isothermal crystallization allowed to determine the temperature dependence of both the crystal growth and the overall crystallization rate that points out the slower crystallization process of nylon 10,7. Isoconversional methods (integral and differential) were applied to evaluate thermal degradation. The mechanism was similar for both nylons (e.g., A and A for nylons 7,10 and 10,7, respectively), although a remarkable difference was determined for the corresponding activation energies (175 and 210 kJ/mol for nylons 7,10 and 10,7, respectively).

中文翻译：

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尼龙 7,10 和 10,7 作为异构奇偶和偶奇聚酰胺的非等温结晶和热降解研究

脂肪族聚酰胺（尼龙）在晶体结构、多晶型转变和晶体形态方面表现出显着的变化，尽管该家族的所有聚合物都具有基于酰胺基团和聚亚甲基链段的简单构成。由具有不同奇偶性(例如偶数或奇数)的二胺和二羧酸衍生的尼龙具有独特的特性，因为当分子链采用典型的全反式构象时，难以建立最佳的氢键几何结构。在这项工作中，研究了具有相同亚甲基/酰胺比率的两种异构奇偶（尼龙7,10）和偶奇（尼龙10,7）聚酰胺。具体来说，结晶动力学是根据量热数据进行评估的，而热降解机制是根据热重分析进行评估的。经典方法（例如，Avrami）与等转化分析一起被考虑用于结晶研究，发现两种尼龙在成核和活化能方面存在显着差异。非等温结晶的等转化分析可以确定晶体生长和总结晶速率的温度依赖性，这表明尼龙 10,7 的结晶过程较慢。应用等转换方法（积分和微分）来评估热降解。两种尼龙的机制相似（例如，尼龙 7,10 和 10,7 分别为 A 和 A），尽管相应的活化能（尼龙 7,10 和 10,7 分别为 175 和 210 kJ/mol）存在显着差异。分别为 10,7)。