A CONNECTION BETWEEN THE MODIFICATION OF SOLVENT DYNAMICS BY POLYMER IN POLYMER-SOLUTIONS AND COMPONENT DYNAMICS IN MISCIBLE POLYMER BLENDS

In polymer solutions it has been established both theoretically and experimentally that the relative time scales for polymer and solvent motions are intimately related to the modification of solvent dynamics upon the addition of polymers. Using experimental data of miscible poly(vinylethylene)/polyisoprene blends, we show that a similar relation also holds in polymer blends. That is, the relative time scales for guest polymer and pure host polymer local motions are closely related to the modification of the host polymer dynamics by the presence of guest polymer. Dynamics in blends rich in polyisoprene resemble the behavior seen in Aroclor solutions of polystyrene. On the other hand, dynamics in blends rich in poly(vinylethylene) bear a strong resemblance to properties of Aroclor solutions of 1,4-polybutadiene or polyisoprene. As Gisser and Ediger have shown in Aroclor solutions of different polymers, one value of an adjustable scaling factor sufficed to bring together the rate at which the addition of guest polymer alters the relaxation time of the host polymer and the relative segmental relaxation times of guest and host polymers for both poly(vinylethylene)-rich and polyisoprene-rich blends. The value of the scaling factor for polymer blends is about a factor of 2 smaller than that found by Gisser and Ediger in Aroclor solutions of polymers.