The structure of a concentrated (4·7 wt %) xanthan broth was probed by dynamic oscillatory, steady shear, and stress-relaxation tests on denatured, renatured, and native xanthan solutions. The range of the shear rates extended down to 10-5 s-1 to test for the existence of a yield stress. Though the viscosities at these very low shear rates were extremely high for polymer solutions (105 Pa. s), no evidence of a true yield stress was found. Long range order was indicated by a difference in complex and steady shear viscosity, presumably arising from inter-chain hydrogen bonding and liquid crystal formation. Differences in recoverable strain between the various samples arise from dissimilar structures and long range interactions in the solutions.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry