Structural Formation during Induction Period of First Order Phase Transition

在一阶相变中，我们有时观察到相变之前的等待时间，即所谓的诱导期（孵化时间）。根据经典成核理论，诱导期是形成临界核所需的时间。然而，具有多阶参数的系统，如复杂液体，由于阶参数的耦合，会表现出各种各样的孵育时间或预转变行为。本研究的目的是揭示复合液体一阶相变的孵育时间或预转变现象的动力学。1)结晶诱导期聚合物的有序过程。我们发现了聚合物结晶诱导期的有序过程。当聚对苯二甲酸乙酯玻璃在刚好高于玻璃转变温度的温度下退火时，在结晶之前，在小角度x射线散射谱中出现了一个新的峰。对该峰的定量分析表明，在结晶的准备过程中发生了一种spinodal分解型的相变。这种现象的起源被解释为棒状聚合物片段的平行取向排序。2)表面活性剂/水体系有序-有序过渡的预过渡现象。在非离子表面活性剂/水体系中，我们研究了从片层到旋回转变之前的片层结构。在高温区（tbb0 ~ 65℃），片层呈波动状。当温度接近片层-陀螺转变温度时，多余的漫射散射在第一个片层峰周围生长，然后在转变温度下转变为陀螺晶格的（211）峰。这种过量的漫射散射是由片层的调制或穿孔引起的。这种调制的片层结构是平衡过渡前结构，对应于片层结构的最不稳定模式。

In the first order phase transitions, we sometimes observe a waiting time prior to the phase transition, so-called induction period (incubation time). According to the classical nucleation theory the induction period is the time needed to form critical nucleus. However systems having multi-order parameters, such as complex liquids will show a variety of incubation time or pretransition behaviors arisen from coupling of the order parameters. The purpose of this study is to reveal the kinetics of the incubation time or pretransition phenomena in the first order phase transition of the complex liquids.1) Ordering process of polymers during the induction period of crystallization.We found the ordering process in the induction period of polymer crystallization.When a poly(ethylene terephthalate) glass was annealed just above the glass transitio temperature, a new peak in the small angle x-ray scattering profiles appeared prior to the crystallization. The quantitative analysis of this peak revealed that a spinodal decomposition type of phase transition occurs as a preparatory process of the crystallization. The origin of this phenomenon is explained as the parallel orientational ordering of the rodlike polymer segments.2) Pretransition phenomena observed in a order-order transition of a surfactant/water system.We investigated the lamellar structure prior to a lamellar-to-gyroid transition in a nonionic surfactant/water system. In high temperature region (T > 65℃) the lamellae show undulation fluctuations. When the temperature approached to the lamellar-to-gyroid transition temperature, the excess diffuse scattering grew around a first lamellar peak and then transformed to a (211) peak of the gyroid lattice at the transition temperature. This excess diffuse scattering arises from modulation or perforation of the lamellae. This modulated lamellae is the equlibrim pretransition structure and corresponds to the least stable mode of the lamellar structure.