Material property NMR imaging of cross-linked polymers based on longitudinal relaxation in the rotating frame

Material property (MAP) NMR imaging is a promising tool for the investigation of materials. It is based on relaxation weighted imaging, which is combined with a theoretical description to relate the measured NMR data, in this investigation represented by T-1 rho relaxation values, with the property of the material one is interested in. Following this concept, T-1 rho images with different strengths of the spin-lock amplitude have been acquired for a rubber sample consisting of three pieces of natural rubber with different cross-link densities. The data were evaluated using a defect diffusion model and transformed into images of the properties of the polymer network. Images related with the cross-link density and the power law of the T-1 rho dispersion, which characterizes the molecular dynamics, have been calculated.