EFFECTS OF BLENDING ON LOCAL CHAIN DYNAMICS AND GLASS-TRANSITION - POLYSTYRENE POLY(VINYL METHYL-ETHER) BLENDS AS STUDIED BY HIGH-RESOLUTION SOLID-STATE C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

To evaluate effects of blending on molecular motion of the individual polymer components in a compatible polymer blend, polystrene/poly (vinyl methyl ether) (PS/PVME), the temperature dependence of C-13 nuclear magnetic resonance linewidth for CH carbon resonance of PVME was studied under conditions of magic-angle spinning and proton dipolar decoupling. The observed temperature dependence was satisfactorily explained by assuming the following effects of molecular motion: (1) averaging the dispersion of isotropic chemical shifts in the glassy state and (2) the interference between local anisotropic motion and high-power proton decoupling. The activation parameters for motion of PVME of the blends were determined, and the compositional dependence is discussed. It is concluded that microscopically homogeneous mixing is achieved for PS/PVME blends.