| Abstract: | Waxy maize starch was hydrolyzed with sulfuric acid in aqueous solution. The remaining starch granules after acid hydrolysis were characterized by TEM and wide‐angle XRD. Starch nanocrystals with size between 40 to 80 nm and relative crystallinity of 63% were obtained after 6 days of hydrolysis. Starch nanocrystals/carboxymethyl chitosan composite films were prepared by casting‐evaporation method. When the starch nanocrystals content was below 30 wt%, the filler dispersed uniformly in the carboxymethyl chitosan matrix, whereas aggregation of starch nanocrystals and phase separation between aggregates and matrix were observed when the starch nanocrystals content was higher than 30 wt%. The maximum tensile strength (TS) of composite films approached ∼29 MPa, which was two times higher than that of the carboxymethyl chitosan film without filling starch nanocrystals. The percentage elongation at break (EB%) of nanocomposite films decreased with the increasing of the starch nanocrystals content. The water absorption and water vapor barrier property of carboxymethyl chitosan film were significantly improved by adding starch nanocrystals. |
