Nuclear magnetic resonance techniques -spectroscopy and imaging- for the nondestructive characterization of polymeric materials and composites
To optimize the system for solid state imaging applications different techniques were implimented. Beside the well known Fourier-Transform-Imaging-Algorithm with frequency and phase information, a back-projection-algorithm and Fourier-Transform-Imaging-Algorithm using only phase information now are available which are more reliable for solid state imaging. All of these algorithms can be combined with special designed pulse sequences for the determination of the relaxation times and to reduce and decouple the dipole-dipole-interactions. By using these parameters the distribution of the spin density and the molecular mobility in a polymer can be determined. For elastomeric materials the inhomogeneity of the crosslink density and aging processes (e.g.oxidation result in a change of molecular mobility. These effects can be determined in a quantitative manner and spatially resolved by using NMR-imaging techniques.