The viscosity of the WPI-XG mixtures is determined for each
batch using the AR-1000N rheometer (TA Instruments, USA) with
cone-plate geometry (60 mm diameter, 4 cone angle) at 25 C.
Shear rate _ c ranged between 0.2 s1 and 2800 s1. The viscosity
of the solutions is affected by the XG concentration, and the addition
of sodium chloride decreases the viscosity. These solutions exhibit
a shear thinning behavior as seen in Fig. 2 and can be fitted
with a power law for shear rates between 0.3 and 700 s1.
l ¼ K _cn1 ð1Þ
where s is the shear stress, K is the flow consistency index and n the
structure index.