Entanglement Dynamics in Miscible Polyisoprene/Poly(p-tert-butylstyrene) Blends

Abstract

Viscoelastic, dielectric, and rheo-optical behavior was examined for miscible blends of high-M cis-polyisoprene (PI) and poly(p-tert-butylstyrene) (PtBS). The slow dielectric relaxation of the blends was exclusively attributed to the global motion of the PI chains having the type-A dipoles. The PI and PtBS chains behaved as the fast and slow (low- and high-friction) components and were well entangled with each other. The dynamics of these chains changed significantly with temperature T. At high T, the blend exhibited two-step entanglement plateau of the storage modulus G′(ω), and the plateaus at high and low angular frequencies (ω) were attributed, with the aid of the dielectric data, to the entanglement among all component chains and that between the PtBS chains, respectively. The entanglement length a characterizing the high-ω plateau was well described by a simple mixing rule based on the number fraction n of the Kuhn segments of the components, a = nPIaPIbulk + nPtBSaPtBSbulk. This result was consiste...