| Abstract Scope |
Direct ink writing (DIW) of sodium alginate (SA) requires inks with optimized rheological properties to achieve stable extrusion and high-fidelity printing. This study presents commercial carbon (AC) and agri-derived biochar (AB) as sustainable reinforcing fillers for DIW-printed SA composites under identical processing conditions. Rheological analysis demonstrated that both fillers enhanced shear-thinning behavior, yield stress, viscoelasticity, and structural recovery, enabling stable extrusion and multilayer shape retention, with SA-AB exhibiting superior printability. Microstructural, spectroscopic, thermal, and tribological characterizations confirmed improved filler dispersion, enhanced thermal stability, and greater wear resistance in the carbon reinforced composites. Furthermore, SA-AB exhibited lower impedance and significantly higher electrical output than SA-AC, indicating enhanced charge transport and interfacial polarization. The superior performance of SA-AB is attributed to its hierarchical porous structure and defect-rich carbon framework. These findings demonstrate that agri-derived biochar is a sustainable, high-performance alternative to commercial activated carbon for multifunctional DIW-printable SA composites. |