Mcr 92

Steady shear properties were measured according to the previous method [32 (link)] with a rheometer (MCR92, Anton Paar, Graz, Austria). The starch paste (6%, w/w) was prepared by using RVA (RVA-Ezi, Newport Scientific Pty. Ltd., Warriewood, Austria) at a rotation speed of 160 rpm, heated from 50 to 95 °C for 3.5 min, and held at 95 °C for 3 min for full gelatinization. Then, the starch sample was rapidly poured into a rotational concentric cylinders, equilibrated at 25 °C for 3 min before analysis, and continuously sheared in the gap (0.099 mm) between the inner cylinder (radius: 26.652 mm, length: 39.999 mm) and the outer cylinder (radius: 28.922 mm) from shear rate of 1 to 100 s⁻¹. Herschel–Bulkley model was applied to describe the flow behavior of the samples at steady shear: $\sigma ={\sigma }_0 + K{\left(\stackrel{·}{\gamma }\right)}^n$
In Equation (2), σ is the shear stress (Pa), σ₀ is the yield stress (Pa), K is the consistency index (Pa.sⁿ), $\stackrel{·}{\gamma }$ is the shear rate (s⁻¹), and n is the flow behavior index (dimensionless).

Four pastes were prepared with a water-to-solid ratio (w/s) of 0.5. The pastes were mixed in an IKA ULTRA TURRAX Tube Drive mixer (Berlin, Germany) for 3 min at 1700 rpm. The rheological tests were started after a total of 5 min from the time of initial contact of the binder with water using a stress-controlled rheometer, Anton Paar MCR 92 (Graz, Austria), equipped with a serrated plate-plate geometry (upper plate of 25 mm diameter and lower plate of 50 mm diameter) at 20 ± 1 °C and a gap of 2 mm between two plates. A solvent trap was used to prevent water evaporation.
The rheological measurements were preceded by preshear and structure recovery intervals to allow for the rejuvenation of the samples and to erase any memory of the shear history exerted by the samples during preparation and loading. The rheological experiments follow two protocols:

The steady shear properties of starch samples were evaluated according to Tsai and Lai [23 (link)]. Samples were first gelatinized by using RVA as described in Section 2.7, then a portion of the starch paste was placed on the stage of a rheometer (MCR92, Anton Paar, Graz, Austria), and was sheared with a parallel plate (diameter = 50.00 mm, gap size = 1 mm) measuring system at 25 °C from shear rates of 0.1 to 100 s⁻¹. The Herschel–Bulkley model was used to describe the steady shear rheological behavior of water caltrop starch paste: $$\sigma ={\sigma }_0+K{\left(\dot{\gamma }\right)}^n,$$
where σ and σ₀ are the shear stress and yield stress, respectively; K is the consistency index; $\dot{\gamma }$ is the shear rate; and n is the flow behavior index.

The rheological properties of the samples were tested using a rotational rheometer (Model: MCR92, from Anton Paar, Austria) [15 (link), 49 (link)–51 (link)]. An appropriate amount of sample was taken and placed on the sample stage, the model of the test rotor was 50 mm for parallel plates, the gap was set at 1 mm, and the test temperature was 25 °C. Set the strain scanning, scanning range 0.01–1000%, logarithmic point, frequency set to 1 Hz. Set up angular frequency scanning, scanning range 0.1–100 Hz, logarithmic point taking, strain setting 1%. Set time modulus profile, linear scan at 0–10 min, gap 0.6 mm, strain 1%. Set the shear mode with a shear rate of 0.1–100 s⁻¹ for the rheological behavior and logarithmic point taking.

The rheological properties of CMC/Al bioinks were measured using a modular rheometer (MCR-92, Anton Paar, Graz, Austria) equipped with a 25 mm diameter parallel plate (PP25, Anton Paar, Graz, Austria) and an adapter (C-PP50/XL, Anton Paar, Graz, Austria). One mL of each bioink was placed on the adapter maintained at 37 °C and equilibrated during measurements using the parallel plate. Viscosity measurements were performed at shear rates ranging from 0.01 to 100 s⁻¹. The amplitude sweep test and frequency sweep test measured the storage modulus (G’) and loss modulus (G″) of the bioinks and provided information on the viscoelastic behavior, shear thinning, and subsequent recovery of the bioinks. In particular, the linear viscoelastic region (LVR) was obtained by an amplitude sweep test to measure shear strains ranging from 0.01 to 100% with an angular frequency of 1 rad/s. A frequency sweep test was evaluated at an angular frequency range of 0.1 to 100 rad/s with a shear strain of 1% where the LVR of each bioink intersected to confirm time-dependent fluid behavior.

Tensile test of the ionic hydrogel was performed by ESM301/Mark-10 system at room temperature. Rheological property test of the us-IHs was performed by Huck rotating rheometer (MCR92, Anton Paar, Austria).

PPP suspensions were stirred overnight at 25°C before testing. Shear stress sweep tests were conducted in a modular compact rheometer (MCR92, Anton Paar, Graz, Austria) with a parallel plate measuring geometry (25‐mm diameter, part No. 79044, Anton Paar, Graz, Austria); using a gap of 500 μm. Then, the resultant steady shear flow curves were analyzed at 25°C, using shear rates from 1 to 100 s⁻¹. Shear stress (σ) and apparent viscosity (η) were measured as a function of shear rate. Data from the flow curves were fitted to the Power law model (Equation 1) to define shear‐effected characterizations of the PPP suspensions. $$\sigma =K\dot{\gamma }n$$ where σ represents the shear stress (Pa), K is the consistency index (Pa.sn), γ˙ is the shear rate (s⁻¹), and n is the flow behavior index (dimensionless).