3.2.4. SEM
SEM photographs relative to the coated and uncoated papers (Fig. 5) show that, the porous structure typical of fiber-based materials was tightly covered by the caseinate-based coating. As coating level increased, uniformity and smoothness of the coating also increased. It can be noted that the resulting coated papers showed good appearance, flexibility and adhesion between the coating and the cellulosic substrate. Caseinate-chitosan “bilayer coatings 2” were more uniform than caseinate coatings and “bilayer coatings 1”. The surface micrographs obtained by SEM revealed that “bilayer coatings 2” completely coated the cellulose fibers, and filled the pores of the paper. However, no observable differences were observed between microscopic views of single-layer coatings and “bilayer coatings 1”.