Development of sustainable PCL/rice husk–derived SiO ₂ composites through fused filament fabrication: Mechanical, degradation, and antibacterial performance

Polycaprolactone (PCL) is widely employed in fused filament fabrication (FFF) for biomedical applications; however, its mechanical strength, hydrophobic nature of the surface, and lack of antimicrobial property are the barriers to its wider use. The rice husk–derived amorphous silica (RH-SiO 2 ), acquired through a sustainable waste valorization route was incorporated with PCL to fabricate multifunctional composites using FFF. The composite filaments with different contents of RH-SiO 2 were extruded and printed, followed by a series of tests on melt flow behavior, dimensional stability, thermal characteristics, mechanical performance, wettability, in vitro degradation, and antibacterial activity. The results of microstructural analysis showed the filler was well dispersed. The optimal 2 wt% RH-SiO 2 reinforcement led to an impressive enhancement of tensile strength (9.95 MPa), compressive strength (29.32 MPa), and surface hardness due to the synergistic effects of increased crystallinity and controlled melt rheology. The change in the contact angle showed a dramatic increase in wettability, while the results of degradation studies indicated that there was a balanced and stable degradation profile with very little pH variation. The printed PCL/RH-SiO 2 composites has a compressive strength within the required range of trabecular bone, making it suitable for biomedical scaffold applications.