*2.5. Rheological Measurements*

The rheological characteristics of PoS and PoS-PPC compounds were analyzed by an MCR 302 rheometer (Anton-Paar, Graz, Austria) with a parallel plate measuring system, according to Kong et al. [24] and Chen et al. [4]. The gels of starch and starch-PPC mixtures obtained from Section 2.4 were transferred to a rheometer board with a probe type of PP50 and a gap of 0.5 mm. The pastes were equilibrated at room temperature for 5 min before measurement.

#### 2.5.1. Steady Shear Analysis

The changes in shear stress of the samples were determined within the range of increasing shear rate from 0–1000 s−<sup>1</sup> and then decreasing from 1000–0 s<sup>−</sup>1. The obtained curve was fitted with the Power Law equation for regression fitting:

$$
\sigma = \mathbb{K} \cdot \gamma^n \tag{2}
$$

where *σ* is the shear stress (Pa). *γ* is the shear rate (s−1). *K* is the consistency coefficient (Pa·sn). *<sup>n</sup>* refers to the flow behavior index (*<sup>n</sup>* < 1 for pseudoplasticity fluid, and *<sup>n</sup>* = 1 for Newtonian fluid).

#### 2.5.2. Dynamic Rheological Analysis

An oscillatory frequency sweep mode (0.2–20 Hz) was conducted at room temperature with 1% strain. The storage modulus (G- ) and loss modulus (G--) were obtained.
