Biochar-reinforced polyamide 12 composites for sustainable selective laser sintering 3D printing: Performance enhancement and carbon footprint reduction

The development of sustainable, high-performance materials for additive manufacturing is crucial for advancing low-carbon technologies. This study investigates biochar, a renewable carbon-rich material derived from biomass pyrolysis, as a functional filler in polyamide 12 (PA12) composites for selective laser sintering (SLS) 3D printing. A comprehensive structure–property–function analysis revealed that incorporating up to 10 wt% biochar significantly enhanced the tensile modulus from 1.4 ± 0.1 GPa to 3.2 ± 0.3 GPa and tensile strength from 43.1 ± 1.2 MPa to 64.7 ± 2.0 MPa, without compromising printability. At higher loadings (>20 wt%), biochar agglomeration and interfacial defects were observed via scanning electron microscopy, leading to reduced mechanical performance. Thermogravimetric analysis showed improved thermal stability, with a shift in peak degradation temperature from 445.5 °C for neat PA12 to 454.0 °C for the composite containing 30 wt% biochar. Rheological characterization demonstrated increased viscosity and elasticity, facilitating better melt strength and SLS processability. Most notably, life cycle assessment (LCA) revealed up to a 66 % reduction in climate change potential for the PA12-BC20 composite compared to pure PA12 when accounting for biochar's biogenic carbon sequestration. These findings establish biochar as a structurally and environmentally advantageous carbon additive, offering a dual benefit of performance enhancement and carbon footprint reduction for advanced sustainable 3D printing applications.