Broadband dielectric investigation of amorphous poly(methyl methacrylate)/poly(ethylene oxide) blends

The segmental and local dynamics of amorphous blends of poly(methyl methacrylate) and polyethylene oxide) (PMMA/PEO) were investigated using dielectric relaxation spectroscopy. The derivative of the dielectric permittivity facilitates the observation of the cooperative segmental relaxation (α _b) in blends with low PEO content, which is mostly masked in ∈″ spectra. For blends aged at room temperature, a DSC endotherm gradually develops near the expected PEO T _m and shifts to higher temperatures with increasing aging time. However, X-ray diffraction from PEO crystals is not observed, indicating that the glassy blends undergo physical aging at room temperature. A relaxation appears in the blends between the PMMA and PEO local relaxations, which we propose is associated with regions of PEO partial order.