The Study Of Low Temperature Plasma-Citric Acid Combined Finishing Of Cotton Fabric

The low temperature plasma only modifies the outmost layer of the material surface and keeps the bulk properties unchanged.The plasma treatment is an environmental-friendly process without the consumption of the water and chemicals.On the other hand,the citric acid is poisonous and does not release the matter which is harmful to human beings during the reaction.Therefore,the combination of the plasma-citric acid to the finishing of the cotton fabric is a new kind of method to develop green textiles.At first the properties of the cotton fabric treated by low temperature plasma was investigated.It was found that the surface of the cotton fabric was etched and the tensile strength and wettability of the cotton fabric were improved.The treatment effect of the oxygen plasma was better than the air plasma.However,the crease-resist property was not improved after the plasma treatment.Secondly,the cotton fabrics were modified by citric acid(CA).The best formulation of the citric acid finish was screened by orthogonal experiment as follows:CA 9%;Na₃CA 1%;SHP 8%;TEA 1.5%;JFC 2 mL/L;bath ratio 1:20;drying temperature 90℃;drying time 5 min;baking temperature 170℃; baking time 1.5 min;take-up 80%.It was found by infrared spectroscopy that the esters were formed between the citric acid and cellulose molecules around 1740 cm^-1.After the CA finish,the crease-resist property of the cotton fabric was improved significantly while the strength retention and whiteness decreased.At last the two kinds of optimal finish procedures such as plasma treatment- baking and baking- plasma treatments were discussed.The influences of the plasma treatment time and power on the finish effect were investigated.It was found that for both procedures,the tensile strength and crease recovery angle of the cotton fabric increased with the increase of the plasma treatment time and power.However,they decreased with the further increase of the plasma treatment time and power.In addition,the whiteness was improved for the baking- plasma treatment procedure while it was reduced for the plasma treatment- baking procedure.Analyzed by the scanning electronic microscopy and infrared spectroscopy,the surfaces of the cotton fabrics were etched notably while no other new functional groups were introduced.Based on the tensile strength,crease recovery angle,whiteness as well as other factor such as the convenience of the process,the best procedure for the low temperature- citric acid combined finishing of the cotton fabric was set up as follows:padding finishing bath→drying(90℃,5 min)→baking(170℃,1.5 min)→plasma treatment(50 W,5 min)→washing by water(80℃,6 min)→airing→drying(90℃,5 min).After such finishing,the warp and weft strength retention of the cotton fabric was 78.2%and 75.35%, respectively,which was 6.4%and 14.06%higher than the normal finishing, respectively.The crease recovery angle was 210°,which was 5.15%lower than the normal finishing while still 99%higher than the control cotton fabric. The whiteness of the treated cotton fabric was 81.75.