ABSTRACT:In this study, we used citric acid (CA) as a crosslinking agent, mixed with biopolymer molecular chitosan, to perform a pad-dry-cure treatment on woolen fabrics to study its antimicrobial effects and physical properties with the help of IR spectroscopy, electron microscopy, and differential thermal analysis. From the experimental results, we learned that CA did not crosslink with the woolen fibers if the woolen fabrics were not oxidized by potassium permanganate and that after oxidization, CA produced esterification with the OOH group of the wool and chitosan and transamidation with theONH 2 group of the wool to form a crosslink. The surface crosslinks of the oxidized woolen fibers were relatively coarse, which is undesirable for shrink-proofing and yet beneficial for the antimicrobial and antiseptic effects of the woolen fabrics. It had a negative effect on the fabric softness, yellowness, stretching resistance, and elongation percentage.

This experiment is to research the chemical compositions of the crosslink of the woolen, oxidized with H 2 O 2 of various concentrations and temperatures, cured with the citric acid and TiO 2 /chitosan liquid of different proportions, and then observed by means of Fourier Transfer Infrared Spectrometer (FT-IR), Scanning Electronic Microscope (SEM), Energy Dispersive Spectrometer (EDS), and Thermo-Gravity Analyzer (TGA). Its antishrinkage, antimicrobes, antiultraviolet, strength, elasticity, softness, and yellowness are also investigated to study the changes in its physical properties. From the result, we can see, under the SEM, the sign of disappearance of woolen scales owing to the destruction by H 2 O 2 oxidization; the more H 2 O 2 and its oxidization temperature, the more serious their destruction. The phenomenon of crosslink is not obvious after oxidization and curing treatment with TiO 2 /chitosan, but it somehow apparently happens to the woolen surface. Because TiO 2 /chitosan does not intertwine with the woolen well, which has few effects of heat, the woolen shrinks less with more H 2 O 2 and oxidization temperatures. Its antishrinkage is better. But the more wash, the more shrinkage. However, TiO 2 covered with chitosan catches less sunlight, and thus cannot suppress or even kill microbes. The woolen processed with nanometer TiO 2 enhances the effect of antiultraviolet, which is better as the density of TiO 2 increases. The strength and elasticity of the woolen are worse for more H 2 O 2 and the higher temperature destroy scales and make the woolen coarse, yellow,and less soft.

This study used chitosan deacetylated to different degrees to process woolen fabrics via the nanometrization of sodium hydroxide of different concentrations. The analysis and determination of the bacterial resistance, shrink resistance, Fourier transform infrared, and dyeability were then carried out for the processed substances. The particle diameter was measured with light scattering and scanning electron microscopy. It was then reduced with 5% and higher concentrations of NaOH, in which the particle diameter was 150-750 nm. As for bacterial resistance, the processed cloth that was not oxidized by H 2 O 2 had better bactericidal and bacteriostatic effects than the cloth that underwent the oxidation process. Chitosan and meso-chitosan had a bacterial-resistance effect on the woolen fabrics. The processed cloth also had a better shrinkresistance rate, but the effect of nanometrization was not obvious. For the dyeability of the woolen fabrics, mesochitosan was better than chitosan. The higher degree of deacetylation of chitosan slightly improved the dyeability. The dyeability increased a little as the temperature of the curing treatment rose and the time of the curing treatment was extended.