A new low-frequency ultrasonic device (50–100 kHz) in highly sharpened end sensors that behave as point sources were examined. The application of this new ultrasonic technique with two sensors coupled in the near field is to explore the relations between the physical properties measured through the evolution of the wave time of flight and structural changes during gel formation which is related to two factors: the ambient temperature and the mechanical resistance of the medium. The network evolution was interpreted by an approach based on the Flory model. The physical significance of this model was shown through a series of experiments using a low-frequency ultrasonic technique. Response curves demonstrate the different stages during gel formation.
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