SURFACE EFFECTS ON CHAIN MOBILITY IN LOADED POLYMERS - NMR APPROACH

It is shown how the NMR approach can be used to characterize the mobil ity of monomeric units which pertain to polymer chains mixed with mine ral fillers. This quantitative approach is illustrated from polydimeth ylsiloxane-silica mixtures; it applies also to carbon black mixed with polybutadiene. Fixed monomeric units located on the surface filler ca n be distinguished from those which pertain to the adsorbed layer. Fur thermore, the kinetics of polymer adsorption and the dynamics of chain moving through mixtures are characterized, using the dynamic contrast of magnetizations of protons attached to monomeric units to distingui sh the adsorbed layer from free chains.