Surface Modification of Cellulose Nanowhiskers and Their Reinforcing Effect in Polylactide

The aim of this study was to improve the dispersability of the cellulose nanowhiskers (CNW) in the nonpolar environment, and to fabricate its biocomposites. The acetylated cellulose nanowhiskers (ACNs) were prepared by introducing the acetyl groups onto the cellulose surfaces. The biocomposites were prepared by incorporating 1, 2 and 3 wt% of the ACN into the polylactide (PLA) matrix by using a solution casting method. From the morphological analysis, it was found that the ACN was dispersed well in PLA matrix because of the surface blocking effect by acetyl groups on the cellulose surface, which led to decrease of surface polarity. Moreover, the ACN showed enhancing effects on the tensile properties, thermal stability, dimensional stability and dynamic mechanical properties of the PLA composites. The ACN promoted crystallization behavior, resulting in an increase in crystallinity for the PLA/CNW composites. From the results of this work, the dispersability of the cellulose can be improved significantly by surface modification, and it can maximize the reinforcing potential of cellulose for the biopolymers.