Dynamic rheology of agar gels: theory and experiments. Part I. Development of a rheological model

A theoretical rheological model for agar gels is proposed, based on the bead and spring model for linear flexible random coils and the model for crosslinked polymers. The model introduces the concept of a temperature dependence of the monomeric friction coefficient, ζ0, of the agar molecule. The model has a random coil-like behavior at high temperatures (close to 373 K), and contributions from a three-dimensional network at low temperatures (close to 273 K). A proposed temperature dependence of the net association rate allows the calculation of the fraction of associated molecules as a function of time and temperature. The proposed model predicts the gelation behavior of agar gels utilizing time–temperature data (cooling curves).