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固体核磁能不能测高分子的结晶啊??

核磁共振技术(NMR)

  • NMR能不能测定高分子的结晶??怎样测定,是不是可以取代X-RAY??
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  • 第1楼2005/06/12

    您看下面的例子;
    Quantitative dependence of crystallinity on degree of branching for hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane]

    Abstract. A series of hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane] samples with various degrees of branching (DB) were adopted to investigate the relationship between crystallinity and DB. The relative degree of crystallization (DC) and DB were determined by x-ray diffraction (XRD) and 13C nuclear magnetic resonance (13C-NMR) measurements, respectively. The corresponding plot of DC versus DB shows quantitative dependence of the crystallinity on DB for the polyether.

    4. Conclusion

    A series of PEHO samples with different DBs were adopted to study the relationship between the crystallinity and DB. The relative DC and DB of PEHO samples were respectively determined by XRD and 13C-NMR measurements. Consequently, a plot of DC versus DB was obtained, which demonstrates the quantitative dependence of the crystallinity on DB of PEHO. DSC results make a useful compliment to the relationship obtained from XRD and NMR. The quantitative relationship between the crystallinity and DB reflects the effect of the molecular structures on the crystalline properties for hyperbranched PEHO.

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  • 第2楼2005/06/12

    Solid-State NMR of Polymers

    NMR spectroscopy has emerged as one of the most important methods for the solid-state characterization of polymers. This report gives an overview of the methods and applications of NMR to relevant polymer problems with an emphasis on how NMR can be used for materials characterization and to understand structure-property relationships in polymers. This report is of interest to both the chemical and pharmaceutical industry.

    The review begins with a discussion of the fundamental principles which underpin solid-state NMR, before leading onto the experimental methods involved, including magic-angle sample spinning, and multi-dimensional NMR. A section is then devoted to polymer structure and conformation, including information on semicrystalline polymers. Polymer morphology is detailed, with a focus on polymer crystallinity and blends. The review is completed with a discussion on polymer dynamics, with particular emphasis on semicrystalline, as well as amorphous, polymers.
    The book comprises a concise expert overview, accompanied by an indexed section containing approximately four hundred references and abstracts from the Rapra Abstracts database. These will provide the reader of this report with a valuable reference for further information relating to the study of polymer microstructure using solid-state NMR.

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  • 第3楼2005/06/13

    relative degree of crystallization 是可以用CPMAS方法直接测定的,如果是绝对定量,对T1短的可以用单脉冲,还有的要根据体系,设计合适的实验方法,有看到测定PE的结晶度的,要用好几个实验组合起来分析的。

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