The Application Of Solid-state NMR In The Analysis Of Polymer Materials

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.