• Influence of biological origin on the tensile properties of cellulose nanopapers

      Kontturi, Katri S.; Lee, Koon-Yang; Jones, Mitchell P.; Sampson, William W.; email: william.sampson@manchester.ac.uk; Bismarck, Alexander; email: alexander.bismarck@univie.ac.at; Kontturi, Eero; orcid: 0000-0003-1690-5288; email: eero.kontturi@aalto.fi (Springer Netherlands, 2021-05-22)
      Abstract: Cellulose nanopapers provide diverse, strong and lightweight templates prepared entirely from sustainable raw materials, cellulose nanofibers (CNFs). Yet the strength of CNFs has not been fully capitalized in the resulting nanopapers and the relative influence of CNF strength, their bonding, and biological origin to nanopaper strength are unknown. Here, we show that basic principles from paper physics can be applied to CNF nanopapers to illuminate those relationships. Importantly, it appeared that ~ 200 MPa was the theoretical maximum for nanopapers with random fibril orientation. Furthermore, we demonstrate the contrast in tensile strength for nanopapers prepared from bacterial cellulose (BC) and wood-based nanofibrillated cellulose (NFC). Endemic amorphous polysaccharides (hemicelluloses) in NFC act as matrix in NFC nanopapers, strengthening the bonding between CNFs just like it improves the bonding between CNFs in the primary cell wall of plants. The conclusions apply to all composites containing non-woven fiber mats as reinforcement. Graphic abstract: