Influence of Printing Parameters and Nozzle Diameter on the Effective Microarchitecture and Compressive Modulus of...

Three-dimensional scaffolds based on triply periodic minimal surfaces (TPMSs) have attracted growing interest in bone tissue engineering because of their high interconnectivity and ability to combine high porosity with mechanical integrity. However, in fused deposition modeling (FDM), printed architecture may systematically deviate from the nominal design, thereby affecting structural fidelity and mechanical performance. This study investigated the influence of FDM processing parameters and nozzle diameter on the effective microarchitecture and compressive elastic modulus of polycaprolactone (PCL) gyroid scaffolds. First, a Taguchi L18 design was used to evaluate the effects of extrusion temperature, printing speed, and flow rate on pore size for two nozzle diameters (0.4 and 0.3 mm). In a second experimental stage, prismatic specimens fabricated at three nominal porosity levels were compression-tested to determine the elastic modulus (E), and measured porosity (ϕ) was quantified by densimetric measurements. A systematic mismatch was observed between the nominal design and the printed scaffold architecture, with both pore size and measured porosity consistently lower than their intended values. The dominant process parameter associated with pore-size variability was nozzle-specific: extrusion temperature contributed most for the 0.4 mm nozzle, whereas printing speed contributed most for the 0.3 mm nozzle. In compression, E decreased with increasing measured porosity, and statistical analysis showed that the E-ϕ relationship was nozzle-dependent. Overall, these findings support a process-structure-property interpretation based on the effective printed microarchitecture rather than on nominal design parameters alone. The experimental stiffness ranges obtained here also provide an exploratory mechanical contextualization relative to reported trabecular bone domains, without implying site-specific scaffold selection.