From waste to value: Functionalized chokeberry-filled PLA filaments for 3D printing

This study investigates the development of functionalized polylactic acid (PLA) filaments incorporating micronized chokeberry pomace (40 % fiber, CF) as a sustainable additive with potential antimicrobial and antioxidant properties. The primary goal was to design a 3D-printing filament that combines mechanical performance with bioactive functionality, offering potential applications in customized, biodegradable products for medical and food-contact uses. Filaments containing 2.5 %, 5 %, and 7.5 % CF were produced and comprehensively evaluated for morphological, mechanical, biological, and thermal characteristics. Scanning electron microscopy confirmed that the 5 % CF filament exhibited the highest homogeneity and smoothest surface, resulting in only a 25 % reduction in tensile strength compared to pure PLA. However, all CF additions similarly decreased elongation at break by approximately 36 %. Pure CF demonstrated bactericidal activity against S. aureus and bacteriostatic effects against E. coli , while CF-containing filaments showed only a bacteriostatic effect against E. coli at 5 % and 7.5 % CF loadings. Antioxidant activity in the filaments decreased significantly—by a factor of 150–300—compared to the pure CF powder. Cone calorimetry revealed a 21–36 % increase in heat release rate (HRR), total heat release (THR), and total organic carbon (TOC), accompanied by higher emissions of CO, CO₂, and NOx, indicating faster thermal decomposition. Printability tests demonstrated that pure PLA and the 2.5 % CF filament were successfully printable, highlighting mechanical toughness as a decisive factor for successful 3D printing, although the threshold value for printability varied depending on printer type.