Direct Pellet Extrusion of Calcined Seashell Particle Reinforced Polylactic Acid Composite

Seashells are calcium-rich biomaterials that can serve as a promising reinforcement for biomedical polymer composites, particularly in 3D-printed bone implants and scaffolds. In this study, polylactic acid (PLA) composites reinforced with seashell powder were produced using the Direct Pellet Extrusion (DPE) method with PLA-seashell composite pellets. The 3D-printed samples were analyzed for their morphology, thermal behavior, mechanical properties, and surface characteristics. Scanning Electron Microscopy (SEM) revealed that the seashell particles were well incorporated and uniformly dispersed within the PLA matrix, with an average particle size of ~10 μm. Elemental analysis identified calcium and oxygen as the main constituents, while a reduction in carbon content post-heat treatment confirmed partial calcination. Mechanical testing showed enhanced tensile and flexural properties up to 6% seashell content; however, the properties declined at higher loadings due to particle agglomeration. Increasing seashell content can reduce surface energy while improving surface adhesion and wettability. As such, PLA–seashell composites are well-suited for biomedical applications, including bone implants, tissue engineering, and drug delivery systems, which offer safety along with tunable mechanical, biological ingrowth, and physical properties.