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莫志深* 张庆新 宋春雷 那天海 于黎 张宏放
(中国科学院长春应用化学研究所，高分子物理与化学国家重点实验室，
长春130022, E-mail: mozs@ciac.jl.cn)
本文利用多种外场诱变方法，系统研究了尼龙11的结构与多晶型。在165℃热诱变结晶的尼龙11结晶度达到最大值。拉伸诱变有利于具有压电性的d′晶型的尼龙11的产生。在电场诱变下，随电场强度的增加，尼龙11晶胞参数增大，分子堆砌更为有序，形成沿电场方向取向的片晶。
尼龙11在拉伸升温诱导结晶过程中存在热诱导和应力诱导结晶的竞争。在一定的拉伸范围内热诱导有利于形成a晶型，在较低温度下，拉伸诱导有利于形成d′晶型。但当二者在尼龙11结晶过程中存在竞争关系。
热诱导结晶处理提高了尼龙11的二次结晶，和主结晶比较，二次结晶的熔点要低。随着热诱导结晶温度的上升，尼龙11的结晶度增加且结晶更完善。不同温度下晶区和非晶区的密度差不是常数，并且椭球粒子的半轴b比半轴a短，这意味着晶体粒子主要在二维平面方向生长。
关键词：外场诱变；尼龙 11; 聚合物晶体结构；多晶型
致 谢：
本工作得到国家自然科学重点基金（No.29934072）和国家重点基础研究专项经费(G1999064806)资助。
参考文献：
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2. 张庆新， 莫志深。 尼龙11结构与性能的研究进展，高分子通报，2001, 6(12)：27
3. Qingxin Zhang, Zhishen Mo, Siyang Liu , Hongfang Zhang, Influence of Annealing on Nylon11, Macromolecules, 2000, 33: 5999-6005.
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Induction Effect of External Fields on Structure and Polymorphism of Nylon 11
MO Zhishen, ZHANG Qingxin, SONG Chunlei, NA Tianhai, YU Li, ZHANG Hongfang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022，E-mail: mozs@ciac.jl.cn）
The degree of crystallinity ranged approximately from 24-42% was determined by WAXD. The radius of gyration Rg, crystalline thickness Lc, non-crystalline thickness La, long period L, semiaxises of the particles (a, b), electron-density difference between the crystalline and non-crystalline regions hc-ha and the invariant Q increased with increasing annealing temperature. The analysis of SAXS data was based upon particle characteristic function and one-dimensional electron-density correlation function. An interphase region existed between the crystalline and non-crystalline region with a clear dimension about
2nm for semicrystalline Nylon 11. Instead of the traditional two-phase model, three-phase model has been proposed to explain these results by means of SAXS.
The crystal transitions of Nylon 11 annealed and drawn at different temperatures (Td) with different drawing ratios were investigated by WAXD. The results showed the crystal transitions of Nylon
11 strongly depended on the thermal history and the conditions of drawing. The d′-form Nylon 11 could
be gradually transformed into a-form when it was drawn at high temperature and a-form was only partly transformed into d′-form when it was drawn at low temperature. It should be due to the effect of the competition between thermal inducement and drawing inducement. The thermal inducement was favorable to produce a-form, while the drawing inducement was favorable to produce d′-form.
The crystal structure of melt crystallized Nylon 11 prepared in various electrostatic environments was investigated by using X-ray diffraction. The experiment results show that the crystal structure of the nylon 11 is strongly dependent on electrostatic fields applied to the sample during solidification. It is found that volume of unit cell increases markedly with electrostatic intensity. Nylon 11 is gradually changed from a-form to d′-form.
Keywords: Inducement of external fields; Nylon 11; Crystal structure; Polymorphism |
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