Component segmental mobilities in an athermal polymer blend: Quasielastic incoherent neutron scattering versus simulation

The local dynamics of the miscible blend of cis-1,4 polyisoprene (PI) (70% by weight) with 1,2 polybutadiene (PVE) (30% by weight) is studied. Quasiel astic incoherent neutron scattering (QENS) experiments have provided the dy namic structure factor for each component in the blend far above the glass transition temperature. Molecular dynamics simulations on the same system h ave given segmental relaxation functions in good agreement with the experim ents. Both methods reveal differences in the mobilities of each component, even at high temperatures, emphasizing intramolecular factors. Remarkably, the segmental relaxation of the PVE component in the PI/PVE blend rich in P I resembles that of PI and not of the pure PVE. (C) 2000 American Institute of Physics. [S0021-9606(00)51719-X].