The conducting and relaxation dynamics of Ag+ ions in poly(ethylene oxide) (PEO)silver triflate (AgCF3SO3) solid polymer electrolytes (SPEs) containing nanosize SiO2 filler and poly(ethylene glycol) (PEG) as a plasticizer were studied in the frequency range 10 Hz to 10 MHz and in the temperature range 303328 K. The comparatively lower conductivity of the plasticized (PEG) PEOAgCF3SO3SiO2 nanocomposite electrolyte system was examined by analysis of the Fourier transform infrared (FTIR) spectroscopy and conductivity data. The electric modulus (M?) properties of the SPE systems were investigated. A shift of the M? peak spectra with frequency was found to depend on the translation ion dynamics and the conductivity relaxation of the mobile ions. The value of the conductivity relaxation time was observed to be lower for the PEOAgCF3SO3 system only with nanofiller SiO2. The scaling behavior of the M? spectra showed that the dynamical relaxation processes was temperature-independent in the PEOAgCF3SO3 and PEOAgCF3SO3SiO2PEG polymer systems, whereas they were temperature-dependent for the PEOAgCF3SO3SiO2 system. However, the relaxation processes of all of theses systems were found to be dependent on their respective compositions. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012