Water Resistance and Barrier Properties Improvement of Paperboard by Poly(Lactic Acid) Electrospraying

This research attempted to improve water resistance and barrier properties of paperboard by electrospraying the material with poly(lactic acid) (PLA). The focus was to reduce the amount of PLA in the coating process and to achieve the thinnest possible PLA coating layer. PLA solutions were prepared at 0.5%, 1%, 2%, 3% and 4% (w/v) in chloroform. PLA solution (10 ml) was sprayed onto the paperboard. The results showed that water and oil contact angles of paperboard were significantly increased after electrospraying. Water and oil absorption was significantly reduced, especially when using PLA concentration of 1%. PLA concentrations below 1% produced too few PLA particles on the surface for full coverage, whereas concentrations above 1% led to an uneven agglomeration of PLA particles on the substrate. The results also showed that water vapour transmission rate and oxygen transmission rate of paperboard were significantly reduced at PLA concentration of at least 1%. On the basis of electrospraying technique, the amount of PLA can be significantly reduced to achieve results comparable to other common coating methods.