Figure 4a illustrates that native cellulose is primarily comprised of aggregated cellulosic fibrils with an irregular shape. In nature, each cellulose fiber is made up of several to hundreds of microfibers that tend to be assembled together and lead to the formation of the compact structure of cellulose . The aggregation of microfibers can contribute to the strong hydrogen bonding between the individual cellulose chains . In addition, each elementary cellulose fiber appeared to be long in length with a rough surface and ow aspect ratio. The aggregation of native cellulose is due to the strong hydrogen bonding system between each individual cellulose microfibril in the macrostructure of cellulose, which is consistent with the literature .