Cross-polarization and magic angle sample

For the morphological discussions, NMR measurements must be carried out in the solid state. The cross-polarization and magic angle sample spinning (CPMAS) for and the solid echo pulse sequence for are practical methods. From CPMAS measurements, the spectrum similar to the solution NMR spectrum is observed. NMR chemical shifts are easily obtained from the CPMAS spectrum. Furthermore, the application of the sequence developed by Torchia supplies Tj in the solid state. However, C NMR measurements are time consuming because of the low natural abundance of C nucleus. Tj of H can be observed easily by the solid echo... 

We report here the application of the solid state carbon-13 1 1R with cross-polarization (CP), high power proton decoupling, and magic-angle sample spinning (MAS) to study the curing of epoxy resins. On the basis of our preliminary studies, we show here the application of solid state carbon-13 NMR spectroscopic data to determine some of the Important parameters such as the gelation point and effective functionality of the epoxy monomers. 

High-resolution N.M.R. of Solids.— The period under review has seen substantial progress in the application of solid-state high resolution n.m.r. techniques to polymers. The techniques comprise " multiple-pulse sequences (MP), dipolar-decoupling (DD), and magic-angle sample rotation (MAR). In addition, cross-polarization (CP) may be used to enhance weak C resonances. These experiments provide both dynamic and structural information as do conventional broadline measurements, but the resolution of individual resonances provides a detailed description of molecular behaviour at the monomeric level. The papers are conveniently divided into dynamic and structural studies, with some small overlap. 

FIGURE 2.12 Results of variable contact time (VCT) experiments for the aromatic peak in the cross-polarization (CP)/magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectrum of a lignite sample. The solid line is a fit to Equation (2.17). (Reproduced from Pan, V.H., and Maciel, G.E. The analysis of three representative premium coals by 13C nuclear magnetic resonance. Fuel 1993 72(4) 451-468. With permission from Elsevier.)... 

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