Effect of process parameters on the void fraction and tensile strength of polyvinyl alcohol produced by fused granulate fabrication

Polyvinyl alcohol (PVA), a water-soluble polymer, can be used to produce smoother surfaces and better dimensional accuracy when used as dissolvable supports during the printing of functional polymers like polylactic acid (PLA). This study investigates the printability of neat PVA using a large-diameter nozzle screw extruder 3D printer and the effect of printing parameters on inter-track voids and surface uniformity. This addresses the limitations of the long print times of current polymer additive manufacturing processes using a large-scale fused granulate fabrication (FGF) process. Using rheology tests, the extrusion temperature was identified, and following an experimental design and regression analysis, the optimum process parameters, among which are motor speed, layer height, and overlap percentage, are determined which achieved minimized void fraction and increased surface uniformity. With optimized parameters, the void fraction was reduced to 1.18%, and the bead height difference reduced to 0.316 mm. The tensile tests showed that the 3D-printed PVA had comparable tensile strengths to those of the FDM-printed and injection-molded PLA and ABS. Through tensile testing, the UTS of PVA produced in this study is measured to be 67.99 MPA, with mean elongation of 15.91%. This study show that PVA can be used as support or binding in the 3D printing of complex composites, benefiting from the water solubility feature of PVA.