A dynamic viscoelastic (DVE) and creep study has been made on five iota carrageenan gelling samples with polymer concentration
C ranging from 1 to 3wt% over a wide range of temperature including the sol-gel transition point. All gel samples below and at room temperature show nearly ideal elastic behavior. The gel point is determined as temperature
Tc at which the storage and the loss shear moduli,
G′ and
G″, follow the power law with the same exponent n, which is smaller than the universal value of 0.66 for chemical gels and decreases monotonously with increasing concentration. Superposition of dynamic and creep data reveals that the power law holds at least four decades at the gel point. DSC measurement on the same samples reveals a broad sol-gel transition. The transition temperature
Tm determined as the peak temperature is found to be close to the gel point
Tc, but always higher than
Tc. At
Tm, the samples are viscous solution at lower
C and viscoelastic at higher
C, clearly indicating that
Tm can not be considered as the gel melting temperature.
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