Probing the Fundamentals of Polymer Melt Crystallization

9732653 Hsaio拟议研究的主要目标是探索聚合物熔融结晶的几个基本问题，包括相变的早期阶段、二次结晶和形变诱导结晶。拟议研究的理由如下。现在已经确定，在聚合物熔体中，在静止和流动条件下，长链分子可以结晶成具有周期性排列的片层和无定形中间层的两相结构。虽然这个过程的动力学可以用成核和生长理论来理解，但在这些条件下在短时间和长时间尺度上形成两相结构的机制需要进一步澄清。本研究旨在利用时间分辨同步加速器SAXS/WAXD、显微镜、光散射和热分析等先进表征技术，系统地研究具有不同分子结构、链刚性、相对分子质量和链支化的聚合物中熔融结晶的基本行为。%这项工作的意义在于熔融结晶过程中相变的可能普遍行为，以及大分子的巨大多样性，这一点尚不完全清楚。通过拟议的研究，可能会对这一主题有更深入的了解。这可以显著提高结晶聚合物应用中结构、形态、工艺和性能关系的关联能力。***

9732653 Hsaio The main objective of the proposed research is to explore several fundamental issues of polymer melt crystallization, which include early stages of phase transformation, secondary crystallization and deformation-induced crystallization. The rationale for the proposed study is as follows. It is now firmly established that, in polymer melt, long-chain molecules can crystallize into a two- phase structure with periodic arrangement of lamellae and amorphous interlayers under quiescent and flow conditions. Although the kinetics of the process can be understood with nucleation and growth theories, the mechanism of forming a two- phase structure at short and long time scales under these conditions, requires further clarification. The proposed research is intended to systematically study the fundamental behavior of melt crystallization in polymers with different molecular architecture, chain stiffness, molecular weight and chain branching using several advanced characterization techniques including time-resolved simultaneous synchrotron SAXS/WAXD, microscopy, light scattering and thermal analysis. %%% The significance of this work lies in the probable universal behavior of the phase transformation during melt crystallization, in the enormous multiplicity of macromolecules, that is yet to be completely understood. With the proposed study, an in-depth understanding about the subject may be obtained. This can significantly improve the ability to correlate the structure, morphology, process and property relationships in the applications of crystalline polymers. ***