Preparation And Characterization Of Active Oxidized Chitosan And Its Modification For Cotton Fabric

In this paper,based on the material of chitosan(CS),on the basis of research the original research,by sodium periodate oxidation for its dialdehyde chitosan(Dialdehyde Chitosan,hereinafter referred to as "D-CS"),using HNO3/H3PO4-NaNO2 selective oxidation system of D-CS further oxidation are highly active Chitosan(Activity Chitosan,referred to as"A-CS"),and then use the A-CS respectively for cotton fabrics(CF),the activity chitosan modified cotton fabric(A-CSMCF)were obtained.Characterization and testing of D-CS yield,hygroscopic moisture recovery rate,oxidation degree and other physical and chemical indicators,analysis of the influence of oxidation conditions on the oxidation degree of D-CS,optimization of process parameters;Using nuclear magnetic resonance spectrometer(NMR),infrared spectrometer(FTIR),scanning electron microscope(SEM),X-ray diffraction(XRD),thermogravimetric analyzer(TG),and other equipment for characterizing the A-CS,and test the A-CS viscosity,solubility in water,free amino content,physical and chemical properties such as isoelectric point,analysis of oxidation conditions on the physical and chemical properties of the A-CS,optimization of process parameters;The physical and chemical indexes of A-CSMCF after modification were characterized and tested,such as strong elongation,wrinkle recovery Angle,capillary effect,whiteness,and antibacterial property,etc.,to explore the effects of different graft rates on the wearability and antibacterial property of the modified fabric.The results show that:(1)Under the standard condition,when the concentration of sodium periodate is 4g/L and the oxidation time is 2h,the content of D-CS aldehyde group is 19.4%.Under standard conditions,when the volume ratio of nitric acid and phosphoric acid is 2:1(v/v),the total volume of nitric acid and phosphoric acid is 15 ml,the concentration of sodium nitrite is 1.4%(the volume ratio of sodium nitrite and mixed acid),and the oxidation time is 3 h,the oxidation degree of A-CS carboxyl group is 56.05%,and the solubility is 136g/L.(2)C and N element analysis and FTIR test results showed that chitosan C2 and C3 secondary hydroxyl groups had been selectively oxidized to aldehyde groups by sodium periodate,while hydroxyl groups at other C sites of chitosan had basically no oxidation.(3)At 1730.1 cm-1,the stretching vibration peak of A-CS carbonyl group a appeared in Ir Spectra.Nanalysis showed that the selective oxidation system of HNO3/H3PO4-NaNO2 had selectively oxidized the C6 primary hydroxyl group on D-CS to carboxyl group,A-CS was successfully prepared.(4)When the concentration of A-CS aqueous solution is 2%,the grafting reaction time is 2 h,and the reaction temperature is 80℃,the weight gain of a-cs on cotton fabric reaches 10.38%;FTIR spectrum shows that there is a new carboxyl stretching vibration peak at 1742.3cm-1,which indicates that a-cs is successfully grafted on cotton fabric through chemical crosslinking.(5)The breaking strength of A-CS modified cotton fabric increased,the whiteness decreased,and the wrinkle recovery angle increased significantly.The a-cs grafted cotton fabric had good antibacterial and washability against Staphylococcus aureus and Escherichia coli,and the antibacterial rate of a-csmcf with grafting rate of 10.38%could still reach more than 90%after 30 washes.