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Autori: M. Aluas, C. Filip
Editorial: Solid State NMR, 27, p.165, 2005.
A novel approach for solid-state NMR characterization of cross-linking in polymer blends from the analysis of 1H-13C polarization transfer dynamics is introduced. It extends the model of residual dipolar couplings under permanent cross-linking, typically used to describe 1H transverse relaxation techniques, by considering a more realistic distribution of the order parameter along a polymer chain in rubbers. Based on a systematic numerical analysis, the extended model was shown to accurately reproduce all the characteristic features of the cross-polarization curves measured on such materials. This is particularly important for investigating blends of great technological potential, like thermoplastic elastomers, where 13C high-resolution techniques, such as CP-MAS, are indispensable to selectively investigate structural and dynamical properties of the desired component. The validity of the new approach was demonstrated using the example of the CP build-up curves measured on a well resolved EPDM resonance line in a series of EPDM/PP blends.
Cuvinte cheie: Thermoplastic elastomers, Cross-linking, Solid-state NMR, CP-MAS, Polarization transfer dynamics