Simple preparation of chitosan nanofibers from dry chitosan powder by the Star Burst system

•Chitosan nanofibers were easily prepared by Star Burst system.•Chitosan nanofibers were characterized in detail.•As the number of passes increased, the nanofibers became thinner.•Mechanical properties of the nanofiber sheet were improved up to 10 passes.•Chitosan nanofibers could be dispersed homogeneously in neutral water. Chitosan nanofibers were easily prepared from dry chitosan powder using the Star Burst system, which employs a high-pressure water jet system. Although the chitosan nanofibers became thinner as the number of Star Burst passes increased, the fiber thickness did not change significantly above 10 passes. Crystallinity and the chitosan nanofiber length decreased after extensive treatment due to the strong collision forces breaking the fibers. The mechanical properties and thermal expansion of the chitosan nanofiber sheets were improved by increasing the number of passes up to 10, but further treatment resulted in a deterioration of these properties.