2.5. Rheological Measurement

Rheological behaviors of SH-CNC/TA hydrogels were analyzed using a rheometer Rotational Rheometer MARS III Haake (Thermo Scientific, Bremen, Germany) equipped with a parallel plate geometry (35 mm in diameter) and a 1 mm gap. Oscillatory frequency sweeps (strain = 1%) was conducted from 0.01 to 10 Hz at 25 °C. The complex modulus (G*) and complex viscosity (η*) were calculated by Equations (1) and (2).

where G′ is the storage modulus, G″ is the loss modulus, and f is the angular frequency.

Recovery rests were carried out by straining sample to failure with increasing sweep strain from 0.1–1000%, and then using the time sweep module to record the recovery of the storage modulus (G′) and loss modulus (G’’) as a function of time. Moreover, the G′ and G″ dependence of time in the continuous step strain for SH-CNC/TA hydrogels were carried out with the change of amplitude oscillatory force from strain of 1% to 300% under the same frequency of 1.0 Hz.