Mechanical properties and physicochemical characteristics of cotton fibers during combing process

This study employs a combination of experiments and molecular dynamics to analyze the mechanical properties and surface damage characteristics of cotton fibers during the combing process. Additionally, it investigates the alterations in physical and chemical properties at the atomic scale resulting from mechanical damage. Raw cotton (RC) is combed to 1st combed cotton (1st CC), 2nd combed cotton (2nd CC) and 3rd combed cotton (3rd CC). It was found that the mechanical properties and crystallinity showed an increasing and then decreasing trend with the process of combing, and the degree of surface tearing increased, and the binding energy of C and O shifted to a lower position. The breaking strength of cotton fibers first increased by 7.4 % and then decreased by 11 % and 7.7 % respectively, and the crystallinity was CrI _(RC) = 70.8 %, CrI _{(1st CC)} = 75.3 %, CrI _{(2nd CC)} = 72.7 %, and CrI _{(3rd CC)} = 71.8 % respectively. The C-O bond and the C-C bond at the amorphous regions are broken after combing lead to the cellulose chain to break, resulting in a decrease in the breaking strength of the fibers. The C-O bond as well as the C-O-C bond angles changes significantly during stretching, and the increase in ordering of the amorphous regions causes an increase in crystallinity.