Preparation of different morphologies cellulose nanocrystals from waste cotton fibers and its effect on PLLA/PDLA composites films

In this paper, the influence of nanocellulose with different aspect ratio on the performance of PLLA/PDLA was explicit through a quantity of test results. Three different aspect ratio nanocelluloses were chemically extracted from waste colored cotton fibers. After acetylated and adding to PLLA/PDLA solution, PLLA/PDLA (LD) composites films were prepared by solution casting method and their properties were investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), tensile testing, oxygen permeability and optical measurement. It was found that nanocellulose play a role as nucleating agent to promote crystallization and was also helpful to form the stereocomplexs crystallites. Wherein, the acetylated cellulose nanospheres (ACNS) had the most obvious effect on crystallinity enhancing. The best oxygen barrier performance of LD composites films was occurred after addition acetylated cellulose nanocrystals (ACNC). Fibrous acetylated cellulose nanofiber (ACNF) had the most influence on tensile property. Furthermore, addition of ACNS, ACNC and ACNF had hardly impact on transmittance and haze of films. It is of guiding significance for the preparation of PLA composite materials applied in different fields.