Effect of ultraviolet light and heat on the properties of cotton cellulose

The changes in properties of cellulose brought about by ultraviolet (UV) irradiation, heat exposure and by a combination of both treatments were determined. The methods of characterizing the changes included breaking strength, color, yellowness index, thermal analysis, dye adsorption as a measure of changes in fine structure of the fibers, and Turnbull's Blue test as an empirical measure of carboxyl content. The exposures increased the color and yellowness of the samples as well as the carboxyl content and decreased dye adsorption and breaking strength. A shift of the decomposition endotherm of cellulose to lower temperatures was also noted. It appears that, under the exposure conditions used in this study, the changes in carboxyl content, color changes, yellowness index and breaking strength induced by heat are accelerated by an initial exposure to UV light but still simulate heat ageing alone. There also appears to be a correlation between breaking strength and dye uptake.