Characteristics analysis of friction stir welded grid-patterned 3D-Printed PLA biocomposites reinforced with activated biocarbon

This study investigates the effect of silane-treated activated biocarbon on the performance of PLA-based bio composites. Experimental results reveal that optimized filler loading significantly improves mechanical, fatigue, and surface properties through enhanced matrix–filler interaction, efficient stress transfer, and crack-arresting mechanisms. Among the tested formulations, specimen P14 exhibited superior mechanical performance, achieving a tensile strength of 131 MPa, flexural strength of 152 MPa, impact strength of 6.2 J, hardness of 82 Shore-D, and exceptional fatigue resistance, sustaining 18,465, 16,452, and 14,236 cycles at 25%, 50%, and 75% of ultimate tensile strength, respectively. Specimen P15 demonstrated the highest water contact angle (78°), indicating improved hydrophobicity due to increased surface-modified biocarbon content and microstructural roughness, which reduced wettability. SEM analysis confirmed these trends, showing plain fracture surfaces in the control, improved dispersion and adhesion in optimized composites, and particle agglomeration at high filler loadings. These findings highlight that tailoring biocarbon content and surface treatment enables the development of PLA bio composites with targeted performance, with P14 offering the optimal balance of mechanical and fatigue properties, and P15 excelling in moisture resistance.