Structural Formation during Induction Period of First Order Phase Transition

在一级相变中，我们有时会观察到相变之前的等待时间，即所谓的诱导期(孕育期)。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，具有多序参数的系统，如复杂的液体，由于序参数的耦合，会表现出不同的孕育时间或转变前的行为。1)结晶诱导期聚合物的有序化过程，发现了聚合物结晶诱导期的有序化过程。当聚对苯二甲酸乙二醇酯玻璃在玻璃化转变温度以上进行热处理时，其小角X射线散射图在晶化前出现了一个新的峰。这一峰的定量分析表明，作为结晶的准备过程，发生了调幅分解型的相变。这一现象的原因被解释为棒状聚合物链段的平行取向有序化。2)在表面活性剂/水体系的有序-有序转变中观察到了预跃迁现象。我们研究了非离子表面活性剂/水体系的层状结构。在高温区(T&GT；65℃)，晶片呈起伏波动。当温度接近晶片到陀螺体的转变温度时，过量的扩散散射在第一层片峰附近增长，然后在转变温度下转变为陀螺体晶格的(211)峰。这种过度的扩散散射是由薄片的调制或穿孔引起的。这种调制片层是等边预跃迁结构，对应于片层结构中最不稳定的模式。

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.