| Abstract
| - Gravimetrical Flory−Rehner experiments are combined with MRI experiments to studythe spatially dependent degree of cross-linking in unfilled, 1,6-hexamethylenediamine-cured poly(isobutylene−p-methylstyrene−p-bromomethylstyrene) terpolymers. MRI relaxometry reveals two protonT2 relaxation decay times in CCl4 swollen specimens: a fast decaying component reflecting the constrainedchain segments near cross-links and entanglements and a slow decaying component originating fromless constrained, remote chains. On the basis of a linear relation between the bulk Mn,eff (number-averagemolecular weight between effective cross-links) and the volume-averaged T2 decay times, MRI allowsthe determination of the local cross-link density in inhomogeneously cross-linked specimens by means ofthe spatially dependent T2 decay times. MRI solvent diffusion experiments reveal that the ingress kineticsof cyclohexane in PIB terpolymers is Fickian. It is shown that the diffusion coefficient varies linearlywith the cure state and the volume-averaged T2 decay times.
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