Nanoparticles significantly reinforce polymers and enhance rheological nonlinearity while the mechanisms are far from being clear. We herein provide a novel strategy to prepare silica network (SN) by burning silica filled ethylene propylene rubber compounds and SN composites by absorbing unentangled polypropylene glycol (PPG) liquid. The SN is explored as the first experimental model imitating the "filler network" in nanocomposites. We investigate rheological responses of SN and its nanocomposites. We find that SN exhibits the soft glassy behavior and dominates the reinforcement and nonlinear behavior of the nanocomposites. On the other hand, by using modulated differential scanning calorimetry and broadband dielectric spectroscopy, we show that a part of PPG chains form glassy and restricted fractions in the interfacial fraction of the nanocomposites. The interfacial fraction contributes additionally to the reinforcement and dominates the dissipation above 10 rad/s. The present study can be helpful for understanding the roles of the interface and filler network in reinforcement and nonlinear behaviors of nanocomposites. (C) 2018 Elsevier Ltd. All rights reserved.