Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto606-8501, Japan.
Graduate School of Advanced Science and Engineering, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima739-8521, Japan.
ACS Macro Lett. 2023 Feb 21;12(2):208-214. doi: 10.1021/acsmacrolett.2c00666. Epub 2023 Jan 25.
The isothermal crystallization from the melt state of syndiotactic polypropylene (sPP) has been studied by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and optical microscopy. The WAXD and SAXS results show the crystallization mechanism near the glass transition temperature in which the crystalline and mesomorphic nodules cover the entire sample with the formation of aggregation regions. For the SAXS analysis, the scattering function for the three-component system has been suggested. Furthermore, to analyze the growth kinetics of the aggregation region for sPP, the time-dependent structure factor combined with the homogeneous and inhomogeneous nucleation-and-growth kinetics has been suggested. The analysis shows that the growth kinetics of the aggregation region for sPP is the homogeneous nucleation-and-growth. The growth velocity of the aggregation region is a natural extrapolation of that of spherulite to the high supercooling region. These results might indicate that the crystallization with the nodular aggregation is a fundamental crystallization process near the glass transition temperature for polymers.
通过广角 X 射线衍射（WAXD）、小角 X 射线散射（SAXS）和光学显微镜研究了间规聚丙烯（sPP）从熔体状态的等温结晶。WAXD 和 SAXS 结果表明，在玻璃化转变温度附近的结晶机制中，结晶和介晶结节覆盖整个样品，形成聚集区域。对于 SAXS 分析，提出了用于三相系统的散射函数。此外，为了分析 sPP 聚集区的生长动力学，提出了与均相和非均相成核-生长动力学相结合的时变结构因子。分析表明，sPP 聚集区的生长动力学是均相成核-生长。聚集区的生长速度是球晶在高过冷区的自然外推。这些结果可能表明，具有结节聚集的结晶是聚合物在玻璃化转变温度附近的基本结晶过程。
