Morphological characteristics and the dynamic mechanical properties of maleic anhydride grafted polypropylene (ppgma) and its clay-filled nanocomposites with different degrees of clay exfoliation have been investigated. fully and partially exfoliated samples were prepared through powered sonication and melt blending, respectively. our results indicated that both mechanical α and β relaxations can be identified. the glass (β) transition of the nanocomposites shifted to slightly lower temperatures for nearly all formulations because of reduced chain cooperative motion. however, the broad α transition became more distinct with increasing clay loading for sonicated nanocomposites, and shifted to higher temperatures due to chain confinement of amorphous polymer chains in the crystalline region. the reinforcement in the glassy storage modulus e' of ppgma was examined by the halpin- tsai theory. the high aspect ratio of clay stacks in the fully exfoliated nanocomposites resulted in a significant increase in reinforcing efficiency. ? 2008 Society of Plastics Engineers.
