Abstract Amide comonomers are common in proteins, which bring chemical confinement to their beta-folding. Furthermore, co-polymerization is a common industrial way to enhance polymer properties. By means of fast-scanning chip-calorimetry (Flash DSC) measurement, we investigated how various amide comonomers (amide 6,6 and amide 12) influence the isothermal crystallization kinetics of polyamide 6. The results show that both amide-6-based random copolymers containing separately 18 mol% of amide 6,6 and 20 mol% of amide 12 crystallize slower than polyamide 6 due to the structural mismatching of amide comonomers in hydrogen-bonding interactions, reflecting the general chemical confinement of co-monomers in copolymer crystallization. However, in the low temperature region, the copolymer holding amide 12 crystallizes even slower than the copolymer holding amide 6,6, opposite to what we usually expected for a higher mobile comonomer of amide 12. We found that the anomalous behavior could be attributed to the temperature region where polyamide 12 crystallizes still slower than polyamide 6,6. Our wide-angle X-ray diffraction results revealed that those amide comonomers retain the habits of their corresponding homopolymers in copolymer crystallization due to their inclusion in the crystalline phase of polyamide 6.

中文翻译：

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酰胺共聚单体对聚酰胺 6 结晶动力学的影响

摘要 酰胺共聚单体在蛋白质中很常见，这给蛋白质的 β 折叠带来了化学限制。此外，共聚是提高聚合物性能的常用工业方法。通过快速扫描芯片量热法 (Flash DSC) 测量，我们研究了各种酰胺共聚单体（酰胺 6,6 和酰胺 12）如何影响聚酰胺 6 的等温结晶动力学。结果表明，基于酰胺 6 的无规由于酰胺共聚单体在氢键相互作用中的结构不匹配，分别含有 18 mol% 酰胺 6,6 和 20 mol% 酰胺 12 的共聚物结晶比聚酰胺 6 慢，这反映了共聚单体在共聚物结晶中的一般化学限制。但在低温区，含有酰胺 12 的共聚物的结晶甚至比含有酰胺 6,6 的共聚物结晶得更慢，这与我们通常对酰胺 12 的流动性较高的共聚单体的预期相反。我们发现异常行为可归因于聚酰胺 12 仍结晶的温度区域比聚酰胺 6,6 慢。我们的广角 X 射线衍射结果表明，由于这些酰胺共聚单体包含在聚酰胺 6 的结晶相中，因此它们在共聚物结晶中保留了相应均聚物的习性。