Structure and properties of monocarboxyl cotton fabrics by graft modification with chitosan

Cotton fabrics were selectively oxidized by HNO3/ H3PO4-NaNO2system and obtained monocarboxyl cellulose,followed by amide crosslinking reaction in chitosan solution,thus prepared chitosan graft-modified monocarboxyl cotton fabric. Effects of oxidation time of HNO3/ H3PO4-NaNO2on the carboxyl content,breaking strength and weighting percentage of the graft modified cotton fabric were studied and it was found that the maximum weighting percentage of 5. 52% was obtained when the oxidation time is 45 min. CP / MAS13C NMR,FT-IR,SEM and XRD tests demonstrated that the primary hydroxyl at C6 site in glucose units of cotton cellulose was selectively oxidized into carboxyl group by HNO3/ H3PO4-NaNO2system,subsequently the amido bond of C—N was formed between amino groups in chitosan and active carboxyl groups on theoxidized cotton fabrics and chitosan film formed on the surface of the oxidized cotton fabrics by the covalent crosslinking. After chitosan graft reaction,the crystallinity of monocarboxyl cotton fabric decreased from 65. 37% to 60. 86%,the breaking strength,whiteness and capillary effect slightly reduced,whereas the wrinkle recovery angle significantly increased.