Molecular Dynamics of Natural Rubber/Layered Silicate Nanocomposites As Studied by Dielectric Relaxation Spectroscopy

The segmental chain dynamics in nonvulcanized and vulcanized natural rubber/layered silicate nanocomposites has been studied by dielectric relaxation spectroscopy. Special consideration has been devoted to the effect of clay type and loading on the time scale of the relaxation processes. Results reveal that the type and concentration of clay do not have in effect on the segmental mode of the NR matrix, while the vulcanization reaction slows down the segmental dynamics. A new mode, slower than the segmental dynamics but faster than the normal mode associated with the chain dynamics, has been observed for both vulcanized and nonvulcanized nanocomposites with fillers having high levels of intercalation. We attribute the new mode to a restricted segmental dynamics of natural rubber chains located at the clay/rubber interfacial regions.