Figure 2.

Shear-thinning and non-thixotropic behavior of 0.5% HA solution (2 MDa) analyzed using the rotational rheometer AR2000 (TA instruments, New Castle, DE, USA), connected to the Rheology Advantage software (Version V7.20) and equipped with an aluminum cone/plate geometry (diameter 40 mm, angle 2°, 64-μm truncation). The viscosity decreases in response to gradual increases of the shear rate over time (upward ramp), and then, the viscosity increases in response to gradual decreases of the shear rate over time (downward ramp). The initial viscosity is recovered through the same intermediate states of the breakdown process: the breakdown of the polymeric network is transient and reversible, and therefore, the original structure of HA is recovered.