Structural Formation during Induction Period of First Order Phase Transition

在一阶相变中，我们有时会观察到相变之前的等待时间，即所谓的诱导期（孵化时间）。根据经典形核理论，诱导期是形成临界形核所需的时间。然而，具有多阶参数的系统，例如复杂液体，会表现出由于阶参数耦合而产生的各种孕育时间或预转变行为。本研究的目的是揭示复杂液体一级相变的孕育期或预转变现象的动力学。1）聚合物在结晶诱导期的有序化过程。我们发现聚合物在结晶诱导期存在有序化过程。当聚合物在结晶诱导期内发生一级相变时，（对苯二甲酸乙二醇酯）玻璃在刚好高于玻璃化转变温度下退火，在结晶之前出现小角X射线散射曲线中的新峰。对该峰的定量分析表明，作为结晶的预备过程，发生了一种亚稳分解型相变。2）表面活性剂/水体系有序-有序转变中的预转变现象我们研究了非离子表面活性剂/水体系中层状-螺旋状转变之前的层状结构。在高温区（T > 65℃），λ_（max）呈起伏波动。当温度接近层片-螺旋转变温度时，过量漫散射在第一个层片峰附近增长，然后在转变温度转变为螺旋晶格的（211）峰。这种过量的漫散射是由薄片的调制或穿孔引起的。这种调制的层状结构是等边缘预跃迁结构，对应于层状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.