物理化学学报

最新录用    

超快扫描量热技术表征高分子结晶动力学

何裕成, 谢科锋, 王优浩, 周东山, 胡文兵   

  1. 南京大学化学化工学院, 国家配位化学重点实验室,南京 210093
  • 收稿日期:2019-05-29 修回日期:2019-08-02 录用日期:2019-08-02 发布日期:2019-08-16
  • 通讯作者: 胡文兵 E-mail:wbhu@nju.edu.cn
  • 基金资助:
    国家自然科学基金(21474050,21734005)以及教育部长江学者创新团队(IRT1252)和中科院交叉学科创新团队项目资助

Characterization of Polymer Crystallization Kinetics via Fast-Scanning Chip-Calorimetry

Yucheng He, Kefeng Xie, Youhao Wang, Dongshan Zhou, Wenbing Hu   

  1. State Key Laboratory of Coordinate Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China
  • Received:2019-05-29 Revised:2019-08-02 Accepted:2019-08-02 Published:2019-08-16
  • Contact: Wenbing Hu E-mail:wbhu@nju.edu.cn
  • Supported by:
    The project was supportedby the National Natural Science Foundation of China (21474050, 21734005), Program for Changjiang Scholars and Innovative Research Team in University (IRT1252), and CAS Interdisciplinary Team, China.

摘要: 高分子结晶行为是高分子材料加工过程研究的热点,因为高分子组分和加工工艺控制着高分子结晶及其产物性能。差示扫描量热仪(DSC)是研究高分子结晶动力学常规手段。但是,普通DSC所能达到的最快降温速率一般无法抑制较快的样品结晶,结晶行为将在等温结晶动力学测试之前发生,因此可进行等温结晶的研究温度范围局限于较低结晶过冷度的高温区域。近年来,具有超快速升降温扫描速率和精准控温的快速扫描芯片量热仪(FSC,其商业化版本Flash DSC 1)得到了广泛应用。FSC可以抑制高分子样品在升降温过程中的结晶成核,避免对之后的结晶动力学测试产生影响。因此FSC技术将高分子结晶动力学的研究温度区间延伸至具有较大过冷度的低温区,加深了我们对高分子结晶成核机理以及高分子工业加工过程的理解。本文首先介绍了由初级成核方程描述的高分子结晶动力学原理,初级成核自由能位垒(ΔG*)和扩散活化能位垒(ΔU)分别控制了高低温区的结晶动力学。我们还总结了FSC技术的发展,包括氮化硅薄膜芯片技术、快速扫描量热仪、商业化Flash DSC 1在不同高分子结晶熔融行为研究中的应用。然后介绍表征高分子等温结晶动力学的方法,其中包括样品制备、质量估算、消除热历史、临界扫描速率的确定等,并举例介绍FSC在高分子结晶动力学研究中的应用,涵盖高分子总结晶动力学、结晶成核动力学、高分子焓松弛对结晶成核的影响、FSC联用技术等方面。应用举例中对应形貌和结晶信息,分析了通过FSC测试得到的结晶成核动力学特点。另外通过比较不同结构特点的高分子,总结了我们对结晶动力学行为的基本理解。总之,FSC技术是一种能够提供相转变动力学和热力学信息的高效工具,特别是应用于分析只能在快速扫描中得到的样品结构变化信息。同时我们希望本文能够帮助读者考虑超快扫描量热技术在其他材料研究上的应用,包括合金、药物、生物大分子等。

关键词: Flash DSC, 高分子, 结晶动力学

Abstract: Understanding the crystallization behavior of polymers is a hot topic of study in polymer processing because polymer components and their processing conditions control the polymer crystallization and product performance. Differential scanning calorimetry (DSC) is the most commonly used technique for the measurement of polymer crystallization kinetics. However, the maximum heating and cooling scanning rates in a conventional DSC apparatus are insufficient to suppress the fast crystallization in most polymers. Therefore, conventional DSC measurements of crystallization kinetics are limited to the high-temperature region with low supercooling for crystallization. In recent years, fast-scanning chip calorimetry (FSC and its commercial version, Flash DSC1) has been widely applied to the study of polymer crystallization kinetics because it helps realize ultra-high heating and cooling rates and allows for precise temperature control. The fast scanning can avoid crystallization and even crystal nucleation during the heating and cooling process before the crystallization kinetics measurements. Hence, the crystallization temperatures for the measurements can be extended to the low-temperature region, thereby providing a deeper understanding of the crystallization mechanism and industrial polymer processing. In this review, we first introduced the fundamentals of the polymer crystallization kinetics described by the rate equation for primary crystal nucleation, which is dominated separately by the activation barrier for diffusion as well as the free energy barrier for primary crystal nucleation in the corresponding low-and high-temperature regions. We also summarized the developments of FSC techniques involving a sensor with a silicon nitride membrane and fast scanning calorimeter, as well as the applications of commercialized Flash DSC 1 to study the crystallization and melting behavior of various polymers. Then, we introduced the experimental details for the crystallization rate measurements, including sample preparation, estimation of the sample weight, erasing thermal history, and determination of the critical scanning rate, followed by the application of FSC measurements to evaluate the overall crystallization kinetics, crystal nucleation kinetics, and influence of glassy enthalpy recovery on crystal nucleation, in addition to the combination of FSC with other analytical techniques. The crystallization and nucleation kinetics with the corresponding morphology or structural information were analyzed, and a basic understanding of the crystallization behavior was obtained by comparing the results for polymers with different structural features. In summary, FSC is demonstrated to be a useful and efficient tool for obtaining information on the kinetics and thermodynamics of phase transitions, especially for the assessable structural states observed only during fast scanning. Furthermore, we hope that this paper would encourage readers to extend the applications of FSC techniques to other materials such as metal alloys, drugs, and biological macromolecules.

Key words: Flash DSC, Polymer, Crystallization kinetics

MSC2000: 

  • O642