Influence of Nozzle Speed on the Crystallinity and Solubility of Polyvinyl Alcohol in Material Extrusion

Material extrusion (MEX) commonly requires support structures, and their rapid removal is essential for improving overall process efficiency. This study investigates the effect of nozzle speed on the crystallinity and dissolution behavior of polyvinyl alcohol (PVA) supports fabricated by MEX. The measured crystallinity values are 28.8%, 25.4%, and 23.7% at nozzle speeds of 20 mm/s, 60 mm/s, and 100 mm/s, respectively. Dissolution rates are measured as 0.2144%/min, 0.2378%/min, and 0.2544%/min at nozzle speeds of 20 mm/s, 60 mm/s, and 100 mm/s, respectively. These results demonstrate that nozzle speed is a key parameter that governs both crystallinity and dissolution behavior of PVA. As a result, higher nozzle speeds not only shorten fabrication time but also produce supports with lower crystallinity. Thus, support structures can be removed more quickly and efficiently at high nozzle speeds. This work provides a new perspective on accelerating support dissolution, demonstrating that PVA crystallinity can be tailored through process parameter control in MEX from a chemical viewpoint, rather than relying on conventional physical approaches.