Physiochemical, optical and mechanical properties of poly(lactic acid) nanocomposites filled with toluene diisocyanate grafted cellulose

Although cellulose nanocrystals (CNCs) have been highlighted as a potential nano-reinforcement in polymer composites, the hydrophilic surface nature of CNCs limits their usage in the composite area due to the poor dispersibility of the CNCs in nonpolar solvent systems. A chemical modification of the CNCs was performed using toluene diisocyanate (TDI) to overcome the limitation in the solvent systems. CNCs and TDI-modified CNCs (mCNCs) reinforced poly(lactic) acid (PLA) films were prepared using the solvent casting method. After the modification, the mCNCs were well dispersed in chloroform with hydrophobic nature. In addition, AFM images and UV-Vis spectroscopy provide clear evidence for a good distribution of mCNCs in the PLA matrix. Thermal and mechanical behaviors of the PLA nanocomposite films with the CNCs and mCNCs were explored based on interfacial forces existing between the surface of the CNCs and the PLA matrix as well as the dispersibility of the CNCs with the increase of their loading levels.