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The paper deals with a method for the estimation of the degree of crystallinity for partially-crystalline isotactic-polypropylenes (i-PP) using high-resolution solid-state C-13 NMR. For this purpose direct polarization C-13 MAS NAIR spectra were measured for i-PP samples with different degrees of crystallinity at 98 degrees C. The areas beneath the resonance lines in these spectra correspond to the number of carbons in particular functional groups, while the widths and shapes of the lines reflect the degree of crystallinity, crystalline modifications, distribution of chain conformations and the chain mobility. The C-13 MAS NAIR spectra, measured using appropriate combination of delay time and high proton decoupling field, made it possible to detect only amorphous domains in the sample. This enabled identification of the lines associated with the amorphous domains in the complete C-13 MAS NAIR spectra and provided sufficient information for reliable estimation of the degree of crystallinity. The heteronucleax Overhauser enhancement of the C-13 NAIR signals due to short delay time was taken into account in our calculations.

Estimation of the Degree of Crystallinity of Partially Crystalline Polypropylenes Using ^{13}C NMR