Cellulose reinforced polymer nanocomposites

The structural hierarchy of lignocellulosic fibers enables the extraction of nano-sized particles. These nanoparticles, known as "nanocellulose" or "cellulosic nanomaterials", essentially comprise mechanically produced cellulose nanofibrils (CNF – Cellulose NanoFibrils) and chemically produced cellulose nanocrystals (CNC – Cellulose NanoCrystals). Cellulose is the structural element of higher plants. It is therefore logical that the main application for cellulose nanoparticles is to exploit this property in the form of reinforcing elements for polymer nanocomposites. Numerous techniques, both experimental and theoretical, have been used to determine the Young's modulus of nanocellulosic materials . A wide range of values has been reported. However, the average modulus value is around 100 GPa for CNF and 130 GPa for CNC . These values are consistent and fully compatible with the development of high-performance nanocomposite materials. Specific modulus, i.e. the modulus normalized to the density of the material, is often used: taking into account the density of crystalline cellulose (1.5-1.6 g.cm ^-3 ), we find specific modulus values of the order of 65 J.g ^-1 and 85 J.g ^-1 for CNF and CNC respectively, values well above that of steel and of the same order of magnitude as that of Kevlar .

The use of nanocellulose as a "nanoadditive" in a polymer formulation not only improves the material's mechanical properties, but also its barrier properties or resistance to swelling. The introduction of cellulose nanomaterials into nanocomposite materials was identified as one of the four greatest breakthroughs since 2000 in the report "Nanotechnology Research Directions for Societal Needs in 2020"