In this paper, a polylactic acid (PLA) composite reinforced by silane modified cellulose nanofibers (S-CNF) was prepared, and the effect of modification of CNF on the mechanical and thermal properties of CNF/PLA composite, as well as the strengthening mechanism were studied. Firstly, cellulose nanofibers were silicified, and then poly (lactic acid) materials and S-CNF/PLA composites with different proportions were prepared by solution casting method. The surface morphology and hydrophobic Angle of S-CNF were characterized by scanning electron microscopy (SEM) and dynamic contact Angle test. The mechanical properties of the composites were studied, and the mechanism of S-CNF strengthening the mechanical properties of the composites was discussed. The results showed that the surface morphology of S-CNF still showed a filament-like appearance after modification. Moreover, S-CNF became hydrophobic and the interfacial compatibility with PLA was improved. The addition of S-CNF improved the mechanical properties of the composites. When the S-CNF content was 3%, the tensile strength, breaking elongation and Young's modulus of the composites were increased by 35.78%, 66.25% and 25.9%, respectively, compared with PLA materials. This is due to S-CNF, as a heterogeneous nucleating agent, can induce the crystallization of PLA matrix. It is of great significance to expand the application fields of PLA materials.
 

CNF; Polylactic Acid; Composites; Silane modification; Properties