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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.

我们成功地可视化了聚合物初晶成核机理的一般图像。迄今为止，人们认为初生晶形核只存在一种机制；即，初生晶核直接在熔体中形成。然而，我们的研究项目表明，实际上也存在其他机制。因此，晶体成核以不同的方式发生，取决于熔体的淬火深度。当淬火深度小或结晶温度高时，通常的机制起作用，但当淬火深度大或结晶温度低时，系统中首先发生刚性段取向波动引起的微相分离，然后开始结晶成核。理论上可以有两种类型的微相分离，双极性和单极性。工业上，后一种类型的微相分离或spinodal分解（SD）类型更为重要，因为它提供了具有均匀，坚韧性能的结晶聚合物材料的理想结构。我们已经成功地用光学显微镜观察到了这种SD模式；在旋量温度下，显微形貌从球晶结构转变为旋量结构。对于SD型，我们还发现了两种从熔体和玻璃中结晶的方法；在工业上，后者更为重要。这些结果的专利正在申请中。作为更基础的研究，我们利用小角度x射线和光散射的方法，提出了结晶诱导期的结构形成机制，包括刚性段的延伸、SD的初期和后期三个步骤。