Development of a quantitative method to evaluate the printability of filaments for fused deposition modeling 3D printing.

Lack of a conventional quantitative characterization method for filament printability has been recognized as a critical barrier to fused deposition modeling (FDM) 3D printing application. In this study, a small molecule drug, indomethacin, was utilized as a model compound. Polymers with various solubility were mixed with model drug and extruded into filaments using hot melt extrusion method. Thirty-two filaments with or without indomethacin were evaluated by texture analyzer to study the correlation between mechanical properties and the printability. Three different texture analysis methods were utilized and compared, and a parameter "toughness" calculated by stiffness test was identified to quantitatively describe the printability of filaments in the FDM 3D printer. The toughness threshold value of printable filament was defined as a process window of certain FDM printing. This study provides a quantitative way to evaluate and predict filament printability, and it has great potential to be applied to FDM filament development and quality control in the pharmaceutical industry.