Abstract: Polylactic acid （PLA）/cellulose nanofiber （CNFs） nanocomposites were prepared through melt blending and injection molding， and the effect of CNFs on their crystallization behavior， rheological and mechanical properties were investigated. The results indicated that CNFs could be uniformly dispersed in the PLA matrix at a small content. CNFs can be used as a heterogeneous nucleating agent to induce the crystallization of PLA， improving the crystallization rate constant and reducing the half crystallization time. Compared to neat PLA， the nanocomposites with 5 wt% CNFs presented a decrease in the half crystallization time from 10.4 min to 2.9 min. The rheological experimental results demonstrated that the lubrication and dilution effects of CNFs reduced the storage modulus and loss modulus of PLA. Compared to neat PLA， the elongation at break of the nanocomposite containing 3 wt% CNFs was improved by 41.2 %.

Key words: poly（lactic acid）, cellulose nanofiber, crystallization behavior, rheological behavior, tensile property