Poly(lactic acid)-based biocomposites reinforced with modified cellulose nanocrystals

This work investigates reinforcing poly(lactic acid) (PLA) nanocomposites using triazine derivative-grafted cellulose nanocrystals (CNCs). A hydrophobic triazine derivative was synthesized and applied to modify CNCs to improve their thermal stability and diminish the hydrophilicity of the nanoparticles. CNCs before and after modification were used to reinforce PLA nanocomposites by a hot compression process. The results of thermogravimetric analysis indicated that the initial thermal decomposition temperature of modified nanocrystals was improved by approximately 100 °C compared to the original CNCs. That is, the thermal stability of modified cellulose nanocrystals was improved due to the shielding effect of CNCs by a hydrophobic aliphatic amine layer on the surface of the nanoparticles. The results of dynamic contact angle measurements revealed a decrease of hydrophilicity of the modified CNCs. The results from scanning electron microscopy and a UV–Vis spectrophotometer revealed that the compatibility between the modified nanocrystals and the PLA was improved. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.