Radio frequency air cold plasma pretreatment to enhance 3D printing performance of tapioca starch by altering its rheological behavior and water migration

Abstract

This work investigated the effect of radio frequency air cold plasma (RFACP) pretreatment in enhancing 3D printing performance of tapioca starch. The results of 3D printing showed that the cold plasma (CP) treatment enhanced printing precision from 75.88% to 89.16% in starch. On the one hand, it could appropriately weaken the fluidity of starch ink to reduce the printing line width. On the other hand, it could enhance the self-supporting ability of starch ink and alleviate the sagging and collapse of 3D patterns. The results of rheological behavior further demonstrated that CP-treated starch exhibited greater gel structure characterized by the increased viscoelasticity, rigidity, and structural recovery capacity. Additionally, CP treatment facilitated the migration of free water into immobilized states within the starch ink and shortened relaxation times, indicating an enhanced water-binding ability of the CP-treated starch. Correlation analysis showed that rheological properties, firmness and water distribution of starch ink were significantly linked with the printability. The improvement of starch 3D printing performance after CP treatment may be attributed to the higher amylose content and more hydrophilic groups (especially carboxyl) generated by CP depolymerization and oxidation effects, which could lead to a denser network structure with greater mechanical strength of starch gel. Overall, this study not only reveals the mechanism that CP treatment enhances 3D printing performance of starch, but also provides a green and effective way to improve the 3D printing performance of starch.