Properties And Structural Characterization Of Selectively Oxidized Chitosan Grafted Cashmere Knitwear

This research used the HNO3/H3PO4-NaNO2 oxidation system to treat the chitosan which soaking in acetic acid solution with non-homogeneous selective oxidation to get carboxylic chitosan.Then get it grafted on cashmere to get the functional ecologic cashmere material.After that,we analysis the oxidation degree change affected by oxidation condition.And describe the isoelectric points,the content of free amino and water-soluble.Studied the effects of selective oxidation of chitosan amide on the graft rate of cashmere,then optimized the graft parameters.We describe and test the physical and chemical properties of the modified cashmere knitwear,such as strength,wrinkle recovery Angle,capillary effect,whiteness,antibacterial property and dyeing property.After that investigate the effects of different grafting rates on the wearable and antibacterial properties of modified cashmere knitted fabric.Then comparing the dyeing properties of cashmere knitting were modified or not.The results show that:(1)At room temperature,when the volume ratio of nitric acid and phosphoric acid was 2:1(v/v),the total volume of nitric acid and phosphoric acid was 15 mL,the concentration of sodium nitrite was 1.4%(w/v),and the oxidation time was 0.5 h-3 h,the carboxyl degree was 43.5%-56.8%.(2)As the oxidation degree of selective chitosan increased,the water content and the water solubility increased gradually;The isoelectric pH value of selective oxidized chitosan is about 4.8-6.0;There was no significant change in the free amino group of chitosan during the oxidation process,indicating that the selective oxidation of HNO3/H3PO4-NaNO2 system had no significant effect on chitosan amino group.(3)NMR and IR tests indicated that the HNO3/H3PO4-NaNO2 system had selectively oxidized the primary hydroxyl group at the C6 position of chitosan to carboxyl group,while the hydroxyl group at other C positions of chitosan had basically no oxidation effect.(4)Selective oxidation chitosan concentration of 2%,grafting time is 2 h,the reaction temperature was 60? liquid reaction under the condition of pH=4.5,the selective oxidation chitosan on the cashmere fabric grafted rate reached 8.31%;Scanning electron microscopy and infrared spectroscopy show that:The electron micrograph shows that chitosan film exists on the surface of cashmere knitted fabric;The ir spectra showed the characteristic absorption peaks of amides ?,amides ? and amides ? at wave number 1630 cm-1,1525 cm-1,1322 cm-1;The characteristic absorption peaks of selective oxidized chitosan appeared in the range of 1030-1160 cm-1;The O-H and N-H stretch vibration absorption peaks of cashmere protein are near wave number 3274 cm-1;It is shown that selective oxidation of chitosan occurs amide chemical reaction with cashmere fabric,and selective oxidation of chitosan molecule covalently crosslinked on cashmere fabric.In addition,thermogravimetric analysis showed that the thermal stability of selectively oxidized chitosan grafted cashmere knitwear was basically the same as that of ungrafted cashmere knitwear.(5)The breaking strength and whiteness of the cashmere fabric modified by selective oxidized chitosan amide decreased slightly,while the crease recovery Angle and capillary effect increased obviously;Selective oxidized chitosan grafted cashmere fabric has good bacteriostasis and water resistance against staphylococcus aureus and escherichia coli;The grafting rate of modified cashmere knitted fabric was 8.31%,and the bacteriostasis rate was still above 90%after 30 times of washing.(6)Selective oxidized chitosan has good dyeing promoting properties.Compared with the unmodified cashmere knitted fabric,the dyeing properties that natural gardenia yellow dye and weak acid brilliant blue 6B dye were used for cashmere knitted fabric grafted by selective oxidation of chitosan are improved remarkably.The K/S value of the cashmere knitted fabric grafted by selective oxidation of chitosan that dyed by natural gardenia yellow dye under 80? reaches 7.64;The K/S value of the cashmere knitted fabric grafted by selective oxidation of chitosan that dyed by weak acid brilliant blue 6B dye under 80? reaches 19.31.Compared with the unmodified cashmere knitted fabric,their K/S value increased by 35.0% and 41.8% respectively.