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STRUCTURE FORMATION DURING THE INDUCTION PERIOD OF CRYSTALLIZATION OF POLYMERS

聚合物结晶诱导期间的结构形成

基本信息

批准号：
10305068
负责人：
KAJI Keisuke
金额：
$ 24.59万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2001
项目状态：
已结题

项目摘要

We have succeeded in visualizing the general image of primary crystal nucleation mechanism of polymers. It has so far been considered that there exists only one mechanism in primary crystal nucleation ; i.e., primary crystal nuclei are formed directly in the melt. Our research project has, however, shown that other mechanisms actually exist as well. Thus, the crystal nucleation occurs in different ways depending on the quenching depth from the melt. When the quenching depth is small or crystallization temperature is high, the usual mechanism works, but when it is large or crystallization temperature is low, microphase separation due to orientational fluctuation of rigid segments occurs first in the system and then crystal nucleation begins. Theoretically there may be two types of microphase separation, binodal and spinodal. Industrially the latter type of microphase separation or the spinodal decomposition (SD) type is more important because it gives an ideal structure of crystalline polymer materials with homogeneous, tough properties. We have succeeded in actually observing such a SD pattern with an optical microscope; the optical micrographic patterns drastically change at around spinodal temperature from spherulitic to spinodal structures. For the SD type we have also found two methods crystallized from the melt and the glass ; industrially the latter is more important. A patent on these results is pending. As more fundamental research by means of small-angle X-ray and light scattering, we proposed a structural formation mechanism during the induction period of crystallization, which consists of three steps, extension of rigid segments, the initial and late stages of SD.

我们已经成功地可视化聚合物的初级晶体成核机制的一般图像。到目前为止，人们认为在初级晶体成核中只存在一种机制，即，在熔体中直接形成初级晶核。然而，我们的研究项目表明，其他机制实际上也存在。因此，晶体成核以不同的方式发生，这取决于从熔体的淬火深度。当淬冷深度较小时或晶化温度较高时，通常的机制起作用，但当淬冷深度较大或晶化温度较低时，由于刚性链段的取向波动，系统中首先发生微相分离，然后开始晶体成核。从理论上讲，可能存在两种类型的微相分离，双节和旋节。在工业上，后一种类型的微相分离或亚稳分解（SD）类型更重要，因为它给出了具有均匀、坚韧性质的结晶聚合物材料的理想结构。我们已经成功地在实际上观察到这样的SD模式与光学显微镜，光学显微图像图案急剧变化，从球晶到spinodal结构在约spinodal温度。对于SD型，我们还发现了从熔体和玻璃中结晶的两种方法;在工业上，后者更重要。这些成果的专利正在申请中。作为更基础的研究手段，小角X射线和光散射，我们提出了一个结构形成机制在诱导期的结晶，它包括三个步骤，刚性段的扩展，SD的初始和后期阶段。