Extensional Flow and Relaxation of Semi‐dilute Solutions of Schizophyllan

Capillary thinning experiments of semi‐dilute solutions of schizophyllan in water and DMSO are performed to determine the relaxation behavior in extensional flows as experienced, for example, in the flow through porous media in enhanced oil recovery. The extensional relaxation time λ_E is found to scale with concentration following a dissimilar power‐law dependency for the two solvents, λ_E ∝ c^1.52 in water and λ_E ∝ c^0.90 in DMSO. It is shown that the extensional flow fields are strong enough to break, and prevent the rebuilding of, intermolecular structures, due to hydrogen bonding that was observed to alter the viscoelastic response in shearing flows of aqueous schizophyllan solutions.