FREQUENCY AND TEMPERATURE-DEPENDENCE OF MOLECULAR AND MICROMECHANICALTRANSITIONS IN PPO PMMA/P(S-G-EO) BLENDS/

The frequency and temperature dependence of molecular and micromechani cal transitions were studied in polymer blends with an interphase. The viscoelastic properties of poly(2,6 dimethyl-p-phenylene oxide) (PPO) and poly(methyl methacrylate) (PMMA) blends that were compatibilized by a poly(styrene-graft-ethylene oxide) (P(S-g-EO)) copolymer were stu died by dynamic mechanical spectroscopy (DMS) and the experimental dat a were compared with an interlayer model. The addition of the copolyme r resulted in a micromechanical transition, and the relation between t he volume fraction of interphase, the activation energy of the microme chanical transition, and the micromechanical transition temperature wa s studied. A qualitative agreement between experiments and theory was achieved. The quantitative difference was explained by partial mixing of PPO and/or PMMA with the copolymer in the interphase. (C) 1996 John Wiley & Sons, Inc.