COMPONENT DYNAMICS IN MISCIBLE BLENDS - EQUALLY AND UNEQUALLY ENTANGLED POLYISOPRENE POLYVINYLETHYLENE/

Miscible blends of 1,4-polyisoprene (PIP) and polyvinylethylene (PVE) are studied using rheo-optical methods to extract the dynamics of each component in the blend. Since orientational coupling contributes to t he birefringence, but not the stress, simultaneous analysis of these o bservables for bidisperse blends is used to determine the coupling coe fficient, epsilon. No systematic dependence of epsilon on composition or temperature was detected. The dynamics of the blend components extr acted using the mean value of epsilon are in good agreement with those observed previously for equally entangled blends: blending causes onl y small changes in the component entanglement molecular weights but dr amatically alters the species' friction coefficients, with the dynamic s of the high T-g species (PVE) being more sensitive to both temperatu re and composition.