Influence of wall thickness on mechanical properties and porosity of additive manufactured polymer-based porous structures for fibula bone regeneration

Abstract

In the recent past, Bone tissue engineering (BTE) has become a potentially effective solution for repairing bone defects. In the meantime, various fields, such as material science, additive manufacturing, and clinical medicine, are interlinked in the fast-emerging field of bone tissue engineering. Additive Manufacturing (AM) is a unique technology that accumulates content rather than waste materials in the form of chips. AM techniques like selective laser sintering (SLS), commonly used to create complex polymer structures, allow for the direct fabrication of complex structural implant components for use in BTE. However, the wall thickness of the product limits the SLS systems. In detail, research into the influence of wall thickness on mechanical properties and scaffold porosity is required to develop such lightweight and complex structures. In this study, Polyamide12-based bone Scaffolds were fabricated using the SLS technique by varying the wall thickness ranging from 0.9 mm to 1.10 mm in steps of 0.05 mm. Compression tests, porosity, scanning electron microscopy, and differential scanning calorimetry were conducted on the fabricated specimens. The studies demonstrated that the higher wall thickness benefits in reduction of porosity. The sample fabricated with a wall thickness of 1.1 mm has about 76% less porosity than the sample fabricated with a wall thickness of 0.9 mm. In addition, the study also found that compression strength decreases as porosity increases. The compressive strength of the scaffolds has been measured to be between 45.62 and 90.67 MPa for a wall thickness between 0.90 and 1.10 mm. The maximum compressive strength of a porous polyamide specimen is 90.67 MPa at a wall thickness of 1.10 mm. The fabricated samples with wall thicknesses of 0.9 and 0.95 mm were not mechanically stable, as their compressive strength values were lower than the compressive strength of human fibula bone (68 N/mm2).