Processing-structure-property relationships of bisphenol-A-polycarbonate samples prepared by fused filament fabrication

Fused filament fabrication (FFF) is one of the most popular additive manufacturing processes. However, structural applications of FFF are still limited by unwanted variations in mechanical strength and structural dimensions of printed parts. To obtain a fundamental understanding of these issues, we focused on the interlayer bonding region of bisphenol-A-polycarbonate samples. The samples were prepared by a low-cost open-source FFF 3D printer, and full three-dimensional (3D) geometrical characterizations were performed on them using X-ray micro computed tomography (micro-CT). The results showed significant geometry variation depending on different printing conditions, including print speed, layer height, and nozzle temperature. Based on the results, we demonstrated the effects of reducing layer height and increasing nozzle temperature as well as compensating material extrusion rate to improve geometric precision. Moreover, uniaxial tensile and Mode III tear tests results showed that there are linear relations between bonding zone geometry and bonding strength. In addition, from the 3D geometry of the resulting printed part, we could estimate the Young's modulus in the extrudate stacking direction using finite element method, which showed good agreement with the measured value. We envision that our findings can contribute to providing guidelines for the selection of printing parameters to improve or customize printing quality. Our experimental data may also serve as benchmark data for future multi-physics simulation models.