Preparation and characterization of α-chitin whisker-reinforced chitosan nanocomposite films with or without heat treatment

α-Chitin whisker-reinforced chitosan nanocomposite films were prepared by solution-casting technique. The α-chitin whiskers were prepared by acid hydrolysis of α-chitin from shrimp shells. The length of the as-prepared whiskers ranged between 150 and 800 nm, while the width ranged between 5 and 70 nm, with the average values being about 417 and 33 nm, respectively. The addition of α-chitin whiskers did not affect much the thermal stability and the apparent degree of crystallinity of the chitosan matrix. The tensile strength of α-chitin whisker-reinforced chitosan films increased from that of the pure chitosan film with initial increase in the whisker content to reach a maximum at the whisker content of 2.96 wt% and decreased gradually with further increase in the whisker content, while the percentage of elongation at break decreased from that of the pure chitosan with initial increase in the whisker content and leveled off when the whisker content was greater than or equal to 2.96 wt%. Both the addition of α-chitin whiskers and heat treatment helped improve water resistance, leading to decreased percentage of weight loss and percentage degree of swelling, of the nanocomposite films.