3.6. WettabilityThe contact angles were measured 1 and 30 s after the drop wasapplied to the sample surface. The contact angle for acetylated andnon-acetylated nanofibers after 1 s was measured to be 75◦and54◦, respectively. These values were reduced to 41◦and 37◦after30 s for non-acetylated nanofibers (Fig. 5), while in both cases, theresults illustrated no significant decrement in water droplet angleeven after 30 s observation. The results show that the acetylationchanged the surface characteristics of the nanofibers from highlyhydrophilic to more hydrophobic. As expected, water wettabilitydecreased drastically after acetylation, which further confirmedthat the chemical modification had indeed occurred at the surfaceof CNF samples. These observations are in good agreement withJonoobi et al. (2012), who reported the acetylation treatment usingacetic anhydride.