Effect of UV irradiation on structure and properties of cotton fibers

The cotton fabric was irradiated for different time periods under UV to investigate the effect of UV irradiation on the structure and properties of cotton fiber when the power density of UV was 100 W / cm. And the surface morphology,degree of polymerization,mechanical properties,thermal stability and whiteness of the cotton fabric were discussed. The results indicated that the increase of irradiation time could lead to aggravation of damages in structure and properties of the cotton fiber. When the cotton fabric was irradiated for 30 s under UV,surface of the cotton fiber was etched and surface roughness of fiber increased. During the initial stage of cracking,the weight loss rate of the cotton fiber showed slightly increased,and the temperature at the largest weight loss rate of the irradiated cotton fiber was decreased by 8 ℃,which suggested that the thermal stability was reduced; and the whiteness of cotton fabric was dropped by 7% and cotton fabric became yellow. The covalent bonds C—C and C—O of cellulose were opened and the breaking strength in warp and weft directions of the cotton fabric was reduced by 21% and 10%,respectively. The degree of polymerization of the cotton fiber was decreased from 692 to 140. Damages in structure and properties of cotton fiber will become more serious as the irradiation time further increases.