Abstract: The cotton fabric was irradiated for different time under UV to investigate the changes of structure and properties of the irradiated cotton fiber when the power density of UV was 100w/cm. And the surface morphology, degree of polymerization, mechanical properties, thermal stability and whiteness of cotton fabric were discussed. The results indicated that the increase of irradiation time cloud lead to aggravation of injuries in structure and properties of the cotton fiber. When the cotton fabric was irradiated for 30s under UV, surface of the cotton fiber was etched and surface roughness of fiber was increased. The temperature at the largest weight loss rate of the irradiated cotton fiber was decreased by 8oC and during initial stage of weightlessness weight loss rate was slightly increased, which suggested that thermal stability was reduced. The whiteness of cotton fabric was dropped by 7% and cotton fabric became yellow. The covalent bonds C―C, C―O of cellulose were opened and breaking strength in warp and weft directions of the cotton fabric were reduced by 21% and 10%, respectively. The degree of polymerization of the cotton fiber was varied from 692 to 140. And it could be predicted that variation of structure and properties of cotton fiber would be enhanced with the continuous increase of irradiation time.

Key words: UV irradiation, cotton fiber, thermal stability, degree of polymerization, breaking strength