【作者】 杨伟；

【导师】 渠荣遴；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本文主要利用固体核磁共振方法,对一些通用高分子材料(塑料、橡胶)进行了分析,包括结构分析、定量分析等,对分析过程中的问题进行了探讨。主要内容如下:应用交叉极化-魔角旋转程序(CP/MAS)、总旋转边带抑制程序(CP/TOSS)和单脉冲延迟采样程序(1PDA),对一系列有代表性的高分子材料固体13C NMR谱进行了分析,讨论了影响实验结果的主要参数;对比了交叉极化-魔角旋转程序与总旋转边带抑制程序对典型高分子材料边带的抑制效果;对单脉冲延迟采样用于高分子材料13C定量分析的可行性进行了探讨。实践表明:由于交叉极化作用的存在,与单脉冲(1pulse)程序相比,采用CP/MAS程序可以极大的提高13C谱图的采集速度,但该程序不能对旋转边带进行有效的抑制,因而给某些旋转边带较多的高分子材料的谱图解析带来一定的困难。一般情况下,采用CP/TOSS程序可以较好地抑制旋转边带的出现,简化谱图,对那些易产生旋转边带的高分子材料,能获得较为满意的实验结果。利用固体核磁进行13C定量分析则是一项较困难的工作,这主要与固体NMR谱峰较宽、谱图分辨率不高有关。实验表明:对于不同的样品,定量误差有很大差异,在信号很强、分辩率较高的情况下,可以得到较精确的定量效果,对于高分子物质,特别是聚合物,1pda程序可以大致确定谱图中各峰所占的比例,进而确定其所代表的核的数量,但是个别样品(如果基线严重弯曲,或者信噪比低)定量误差比较大。测定了高分子方面一些典型的含Si、P的化合物,并对其信号进行了指认和说明。文中对聚乙烯的晶区、非晶区信号进行了分辨,通过分峰拟合确定了其结晶度,并与密度法所得结果进行了对比;讨论了在接枝聚合物以及共聚物的分析中出现的一些问题。更多还原

【Abstract】 This thesis concentrates on the structural analysis of some common polymer materials, such as plastics and rubbers, using the method of solid state NMR, several with quantitative analysis. There are comments about the problems in the analysis. Main contents are as follows:A series of typical polymer materials were analyzed using the experiments of Cross Polarization/Magic Angle Spinning(CP/MAS), Cross Polarization/Total Suppression of Spinning Sidebands(CP/TOSS), and 1 Pulse Delayed Acquisition(1 PDA) in the solid state NMR. The main parameters associated with the results are discussed. The sidebands suppression efficient of the CP/MAS and CP/TOSS experiments were compared with each other. The quantitative reliability of 1 PDA experiments for the 13C NMR analysis of polymer materials was discussed. It is indicated that compared with the 1 pulse experiment, the CP/MAS program can extremely speed up the acquisition for the reason of cross polarization. But the CP/MAS program can not suppress the sidebands efficiently. This can make the analysis of the spectrum difficult while there are excessive sidebands in some polymer materials. Generally speaking, the CP/TOSS program can finely suppress the sidebands and make the spectrum simple to read. It can have a good result for the polymers which are easy to produce sidebands. However, it is hard to deal with the quantitative analysis in the solid state NMR, both because of the broad line and the low resolution. The experiments indicated that the error of the quantitative analysis is variable for different samples. If the signal noise ratio and resolution is very well, the quantitative results will be more accurate. For the macromolecues, especially the polymers, the 1 PDA experiments can tell the rough results for the quantitative analysis. Then the number of nuclei of each peak can be determined. But the error of the results can be large for some certain samples (if the baseline is rough or the signal noise ratio is low).Some typical polymer materials containing silicon or phosphorus are measured, the peaks are assigned and illustrated. The crystal and amorphous signals in the polyethylene are distinguished in the paper. The degree of crystallinity was determined using the peak fitting method, and have compared with the results of density method. The problems in the analysis of graft polymers and copolymers are also discussed.更多还原