The general aspects of polymer crystallization under external flow, i.e., flow-induced crystallization (FIC) from fundamental theoretical background to multi-scale characterization and modeling results are presented. FIC is crucial for modern polymer processing, such as blowing, casting, and injection modeling, as two-third of daily-used polymers is crystalline, and nearly all of them need to be processed before final applications. For academics, the FIC is intrinsically far from equilibrium, where the polymer crystallization behavior is different from that in quiescent conditions. The continuous investigation of crystallization contributes to a better understanding on the general non-equilibrium ordering in condensed physics. In the current review, the general theories related to polymer nucleation under flow (FIN) were summarized first as a preliminary knowledge. Various theories and models, i.e., coil–stretch transition and entropy reduction model, are briefly presented together with the modified versions. Subsequently, the multi-step ordering process of FIC is discussed in detail, including chain extension, conformational ordering, density fluctuation, and final perfection of the polymer crystalline. These achievements for a thorough understanding of the fundamental basis of FIC benefit from the development of various hyphenated rheometer, i.e., rheo-optical spectroscopy, rheo-IR, and rheo-x-ray scattering. The selected experimental results are introduced to present efforts on elucidating the multi-step and hierarchical structure transition during FIC. Then, the multi-scale modeling methods are summarized, including micro/meso scale simulation and macroscopic continuum modeling. At last, we briefly describe our personal opinions related to the future directions of this field, aiming to ultimately establish the unified theory of FIC and promote building of the more applicable models in the polymer processing.

中文翻译：

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外流下的聚合物结晶

介绍了外部流动下聚合物结晶的一般方面，即从基本理论背景到多尺度表征和建模结果的流动诱导结晶 (FIC)。FIC 对于现代聚合物加工至关重要，例如吹塑、铸造和注塑成型，因为日常使用的聚合物中有三分之二是结晶的，几乎所有聚合物都需要在最终应用之前进行加工。对于学术界来说，FIC 本质上远离平衡，其中聚合物结晶行为不同于静态条件下的行为。对结晶的持续研究有助于更好地理解凝聚态物理学中的一般非平衡有序。在目前的审查中，首先总结了与聚合物流下成核（FIN）相关的一般理论作为初步知识。各种理论和模型，即线圈拉伸转变和熵减少模型，与修改版本一起简要介绍。随后，详细讨论了 FIC 的多步排序过程，包括链延伸、构象排序、密度波动和聚合物结晶的最终完善。这些成就得益于各种联用流变仪的发展，即流变光学光谱、流变-IR 和流变-x 射线散射，这些成就有助于透彻了解 FIC 的基本原理。介绍了选定的实验结果，以展示在 FIC 期间阐明多步骤和层次结构转换的努力。然后，总结了多尺度建模方法，包括微/中尺度模拟和宏观连续体建模。最后，我们就该领域的未来发展方向简要阐述了个人的看法，旨在最终建立FIC的统一理论，推动建立更多适用于聚合物加工的模型。