Correlation Analysis of 3D Printability and Rheological Properties of Sodium Alginate Hydrogels

In this study, Ca²⁺-induced sodium alginate hydrogel was used as a model. The rheological properties were measured via steady-state shear, oscillation strain sweep, and yield stress. The network of sodium alginate hydrogels was analyzed using water distribution and rheological parameters. After a comprehensive analysis of the morphology and Micro-CT structure of 3D printing products, the mathematical relationship between rheological parameters and 3D printing effect was established using the Spearman's correlation analysis. The results showed that the highest score of 3D printing product was prepared at the mass ratio of SA to Ca²⁺ at 24:1 and the concentration of SA at 4.5%. At the same time, the filament structure of 3D printing product was fine and the porosity was 12.21%. Rheological parameters of K, η₁, G', G", τ₀ and τ_y were 255.1 Pa·sⁿ, 2740 Pa·s, 3509 Pa, 673.2 Pa, 261.4 Pa, and 51.62 Pa, respectively. The capillary water (about 99.20%) was dominant in the gel network, showing strong water holding capacity of hydrogel. Results of correlation analysis showed that the viscosity properties (K, η₁, and G") were negatively correlated with the extrudability, and the correlation coefficient was -0.577. The self-supporting capacity of the 3D printing product was positively correlated with the elastic modulus and stress (G', τ₀, and τ_y) (P<0.05).