Aging of polymer networks as studied by material property NMR imaging

Relaxation-weighted NMR imaging is a powerful tool for the investigation of aging processes in rubber networks, in particular if it is combined with a theoretical description to relate the NMR data with suitable parameters of the material. Following this concept, spin-spin relaxation decays in rubber samples, consisting of differently aged pieces of natural rubber have been acquired in a spatially resolved experiment. The data were evaluated using a dynamical model and transformed into images of those material properties, which are affected by the aging process. Images representing the crosslink density and the correlation times, which characterize the polymer chain dynamics, have been calculated. The differently aged rubber pieces can be easily discriminated in such material property (MAP) images.