<p>Industrial applications of microfibrillated cellulose (MFC) and nanofibrillated cellulose (NFC) have been in<br />use for some time however, there is a need to improve the production steps and at the same time to obtain better quality<br />products. NFC and MFC were generated from NaBH4-modified kraft pulp, produced from a red gum tree plant (Eucalyptus<br />camaldulensis). The generated NFC and MFC were characterized by high-performance liquid chromatography, Fourier<br />transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and 13C-nuclear magnetic resonance (NMR).<br />Morphological and viscoelastic properties were investigated by scanning electron microscopy and rheometry, respectively.<br />The storage moduli of biofilms produced from NFC and MFC were investigated by dynamic mechanical thermal analysis<br />(DMTA). Both exhibited mostly identical FTIR spectra. When the spectra were compared with those of NaBH4-modified<br />kraft pulp, minor shifts were observed due to crystallinity. In NMR spectra, disordered cellulose structures were observed<br />for both NFC and MFC, and these findings were also confirmed by differential scanning calorimetry. Rheology studies<br />revealed that the lowest viscosity was observed with MFC. TGA results showed that NFC degraded earlier compared with<br />NaBH4-modified kraft pulp. DMTA exhibited that NFC films had about six times higher storage modulus compared with<br />MFC.</p>