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 ex perimentally that the relative time scales for polymer and solvent mot ions are intimately related to the modification of solvent dynamics up on the addition of polymers. Using experimental data of miscible poly( vinylethylene)/polyisoprene blends, we show that a similar relation al so holds in polymer blends. That is, the relative time scales for gues t polymer and pure host polymer local motions are closely related to t he 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 pr operties of Aroclor solutions of 1,4-polybutadiene or polyisoprene. As Gisser and Ediger have shown in Aroclor solutions of different polyme rs, one value of an adjustable scaling factor sufficed to bring togeth er the rate at which the addition of guest polymer alters the relaxati on time of the host polymer and the relative segmental relaxation time s of guest and host polymers for both poly(vinylethylene)-rich and pol yisoprene-rich blends. The value of the scaling factor for polymer ble nds is about a factor of 2 smaller than that found by Gisser and Edige r in Aroclor solutions of polymers.