Rheological properties of poly(ethylene oxide)/poly(vinylidenefluoride)-(hexafluoropropylene) immiscible polymer blends were studied in the low frequency domain. According to the blend composition, two critical compositions were determined by theology. These compositions exhibit a power law relaxation spectrum with a critical exponent A. This observation leads us to compare the evolution of the morphology in a binary blend with the process of gelation. The supermolecular structure at the limit of the cocontinuity zone is comparable to the chemical or physical incipient network obtained during the gelation. This point is discussed in term of self-similar superstructure and fractal dimension. (C) 2005 The Society of Rheology.