The crystal structure of polycapryllactam (nylon 8) and of polycapriclactam (nylon 10)
The crystal structure of polycapryllactam (nylon 8) and of polycapriclactam (nylon 10)
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聚辛内酰胺（尼龙 8）和聚己内酰胺（尼龙 10）的晶体结构
DOI：
10.1002/macp.1978.021790225
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
R. Zannetti
中科院分区：
文献类型：
--
作者：
G. Cojazzi;A. Fichera;V. Malta;R. Zannetti
根据单轴取向纤维的X射线衍射图，确定了尼龙8和尼龙10的结构。它们以单斜晶系(伪六方晶系)结晶，空间群为P21/b，晶胞中有四个单体单元。尼龙8的结晶学参数为：a=4，77；b=9，54；c=21，9 A；γ=12 0°；尼龙10的结晶学参数为：a=4，78；b=9，56；c=2 6，9 A；γ=12 0°(c纤维轴)。这两种结构都显示出γ类型的分子堆积，其特征是纤维重复距离缩短和酰胺基团扭曲。因此，通过氢键连接的平行链形成折叠的片状，相邻片状中的链的方向交替地向上和向下。这些结构的结果与尼龙6和尼龙12的γ形式非常相似，再次表明，在这个系列中，通过增加亚甲基的数量，通常的晶体结构变成γ形式。
From X-ray diffraction patterns of uniaxially oriented fibers, the structures of Nylon 8 and Nylon 10 were determined. They crystallize in the monoclinic system (pseudohexagonal), space group P21/b, with four monomeric units in the unit cell. The crystallographic parameters of Nylon 8 are: a=4,77; b=9,54; c=21,9 A; γ=120°, and those of Nylon 10: a=4,78; b=9,56; c=26,9 A; γ=120° (c fiber axis). Both structures show a γ-type molecular packing, characterized by a shortening of the fiber repeat distances and by a twisting of the amide groups. Therefore, pleated sheets of parallel chains joined by hydrogen bonds are formed and the direction of the chains in adjacent sheets is alternately “up and down”. These structures result very similar to those of Nylon 6 and Nylon 12 in γ-form, demonstrating once more that, in this series, by increasing the number of methylene groups, the usual crystal structure becomes the γ-form.