WHITENESS INDEX ON COTTON FABRICS DUE TO CHITOSAN CURING TEMPERATURE

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1 WHITENESS INDEX ON COTTON FABRICS DUE TO CHITOSAN CURING TEMPERATURE Eva Bou-Belda, Marilés Bonet-Aracil, Pablo Díaz -García, Igancio Montava Departamento de Ingeniería Textil y Papelera, Universitat Politècnica de València, Alcoy, Spain Corresponding author: M.Bonet-Aracil; mabaor@txp.upv.es Extended abstract Chitosan is an N-deacetylated biopolymer derivative of chitin (2-acetamido-2-deoxyβ-D-glucose through a β (1-4) linkage). The deacetylation is never complete. There is no specified nomenclature that describes the degree of deacetylation [1]. Chitin can be easily acquired from crab or shrimp shells. Its N-deacetylation is performed under alkali environment. The chitin that has been obtained from the shells is deacetylated in 40% sodium hydroxide at 120 C for 1-3h. This produces 70% deacetylated chitosan. Most natural polysaccharides are neutral or acidic, but chitin and chitosan are highly basic polysaccharides [2]. The bonding between chitosan and cotton is a difficult bond because of the likeness of the two polymers. To improve the bond the chitosan is dissolved in an acid. After that, chitosan is able to react with oxidised cotton fabric, for this reason it has a wide range of applications. It is most known for its use in wound dressing [3-5]. However, it can be used in a lot of other areas, such as cosmetics, as artificial skin, as contact lens, for heavy metal capturing in polluted water, colour removal in textile mills, paper finishing, drug delivery system, etc. But its most important feature might be the fact that is an antibacterial agent [2, 6-7]. It should be pointed out that to carry out the covalent bond formation between the -OH groups of cellulose and the NH2 groups of chitosan, it is necessary to apply high temperature of curing after the treatment giving a better fixation in this case [8]. In order to study the influence of the concentration of chitosan used to treat the cotton fabric and the optimum temperature in the curing, the whiteness test was performed to see a change of colour in the cotton. Material Medium molecular weight chitosan (supplied by Sigma-Aldrich) was dissolved in an acetic acid solution (mass concentration of 1%). Bleached cotton fabric with 210 g/m2 was padded with chitosan solutions of various concentratios getting a wet pickup around 85%. The padded fabrics were then dried at 80 C for 5 minutes and cured using different temperatures for 3 minutes.

2 Treatment of the cotton Table 1 shows the samples treated using different chitosan concentrations and different temperatures in the curing process. Table 1. Different cure temperatures of the chitosan for different concentrations of chitosan. Chitosan concentration Curing Temperature (ºC) (g/l) Whiteness test Treated samples were prepared for colour measurement, which was carried out by following a standard procedure. Colour values were evaluated in terms of CIELAB values (L*, a*, b*, c*, h) using illuminant D65/10 observer on Minolta CM-3600d UV-visible spectrophotometer. On the basis of the results from the spectrophotometer for each cotton sample, additional color parameter was calculated: the whiteness, which was calculated according to CIE formulas as follows: W CIE = Y (x o - x) (y o - y) Results Figure 1 shows the whiteness results from fabrics treated with diverse chitosan concentrations and cured at different temperatures.

3 W CIE Temperature ( C) Untreated Figure 1. Whiteness after treatment with chitosan curing at different temperatures The results show that the whiteness of the fabric decreases faster when the curing temperature is 160 C. This can be explained by the decomposition of cotton at high temperatures. In order to be able to assign the variations to the chitosan treatment, an untreated sample was cured at the same temperatures to determine the natural variation due to cotton behaviour. Results below 160 C are similar if cotton is compared with the treated ones. The decrease in whiteness for the untreated sample starts at 180 C. Conclusions The whiteness test shows a decrease in whiteness due to the effect of temperatures when they are higher than 160 C. Treatments with temperatures lower than 160 C will not show any difference in whiteness. On the other hand, treatments with temperatures higher than 160 C will reflect a considerable and sensitive change on the appearance of the fabrics. This can be attributed partially to cotton degradation but mainly to chitosan decomposition. References 1. Muzzarelli, R. A. (1973). Natural chelating polymers; alginic acid, chitin and chitosan. In Natural chelating polymers; alginic acid, chitin and chitosan. Pergamon Press.

4 2. Kumar, M. N. R. (2000). A review of chitin and chitosan applications. Reactive and functional polymers, 46(1), Gupta, D., & Haile, A. (2007). Multifunctional properties of cotton fabric treated with chitosan and carboxymethyl chitosan. Carbohydrate Polymers, 69(1), Fei Liu, X., Lin Guan, Y., Zhi Yang, D., Li, Z., & De Yao, K. (2001). Antibacterial action of chitosan and carboxymethylated chitosan. Journal of Applied Polymer Science, 79(7), Shirvan, A. R., Nejad, N. H., & Bashari, A. (2014). Antibacterial finishing of cotton fabric via the chitosan/tpp self-assembled nano layers. Fibers and Polymers, 15(9), Vartiainen, J., Rättö, M., Tapper, U., Paulussen, S., & Hurme, E. (2005). Surface modification of atmospheric plasma activated BOPP by immobilizing chitosan. Polymer Bulletin, 54(4-5), Wen, Y., Yao, F., Sun, F., Tan, Z., Tian, L., Xie, L., & Song, Q. (2015). Antibacterial action mode of quaternized carboxymethyl chitosan/poly (amidoamine) dendrimer core shell nanoparticles against Escherichia coli correlated with molecular chain conformation. Materials Science and Engineering: C, 48, Liu, X. D., Nishi, N., Tokura, S., & Sakairi, N. (2001). Chitosan coated cotton fiber: preparation and physical properties. Carbohydrate Polymers, 44(3),

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