Effects of design, porosity and biodegradation on mechanical and morphological properties of additive-manufactured triply periodic minimal surface scaffolds

Abstract

The main aim of this paper is to assess the impacts of design, porosity, and biodegradation on the mechanical and morphological properties of triply periodic minimal surface (TPMS) scaffolds. The TPMS scaffolds were designed and manufactured with different porosities by using fused deposing modeling (FDM) technique. The biodegradation test on the scaffolds was performed for four and six months. The mechanical properties were assessed employing ASTM standard compression test and an in-situ mechanical testing stage. Microcomputed tomography (Micro-CT) technique was used to investigate detailed morphological properties of the scaffolds in 3D. Results indicate that the Schwarz-D scaffolds exhibit the highest compressive strength in lower porosity scaffolds but lose mechanical properties when the porosity was increased. On the contrary, Gyroid scaffolds maintain their strength as the porosity was increased. In addition, Gyroid scaffolds preserve a higher percentage of their compressive strength after six months of biodegradation. It was also observed that biodegradation phenomenon transformed the mechanical failure mode of the scaffolds from ductile to brittle. Morphological analysis of the scaffolds revealed detailed information, which support and clarify the observed variations in the mechanical properties.

Keywords: Additive manufacturing; Biodegradation; Mechanical properties; Microcomputed tomography; Polymeric scaffold; Triply periodic minimal surfaces (TPMS).