Dynamic mechanical properties of aqueous gellan solutions in the sol-gel transition region

Influence of the gelation of aqueous gellan solutions on the dynamic viscoelastic behavior was investigated. Dynamic shear moduli for aqueous gellan solutions (0.60-3.0wt%) were determined over the frequency range from 0.01 to 10Hz and the temperature range from 10 to 60 degrees C by the method of annular pumping between coaxial cylinders. Cole-Cole diagrams in the complex viscosity were constructed, considering temperature and frequency as variables. The complex viscosity was characterized by the circular are in the viscoelastic gel region and by the skewed circular are in the sol region. The change in the relaxation from circular are to skewed circular are caused by gelation was interpreted in terms of the change in the frequency dependency from :he Cole-Cole type to the Williams-Watts type. Copyright (C) 1996 Elsevier Science Ltd