Component Dynamics in Polymer/Polymer Blends: Role of Spatial Compositional Heterogeneity

作者：Sharma Ravi P; Green Peter F^*

来源：Macromolecules, 2017, 50(17): 6617-6630.

DOI：10.1021/acs.macromo1.7b00092

The segmental relaxation times tau(A) and nu B of the A and B components, respectively, of an A/B polymer/polymer blend typically exhibit dissimilar temperature dependences and can differ by orders of magnitude, thereby manifesting the influence of spatial compositional heterogeneity. We show that for weakly miscible A/B blends the relaxations of the faster A component occur via separate and distinct mechanisms. In the melt state, tau(A) increases in a nonlinear manner as temperature T decreases toward blend glass transition temperature T-g((blend)) (or toward the local effective glass transition temperature of its component Tg(A)) this is the typical a relaxation process. For temperatures below the transition, 1/tau A exhibits an Arrhenius temperature dependence; this is identified as the a' process. A third relaxation process, a so-called alpha o process, also occurs in the melt state; it is slower than the a process and exhibits a significantly stronger dependence on temperature. Each relaxation process, characterized by a different dependence on temperature, occurs via a different mechanism and associated local composition. This behavior, the existence of the ao and a' relaxations that accompany the a relaxations, would occur in miscible and weakly miscible blends whose component Tgs differ significantly.

• 出版日期2017-9-12