ABSTRACT
Denim color fading ozonation is dissimilar from other ozone applications as it is employed with distinctive parameters and on special products. In this study, yarns of cotton, lyocell and PET treated by denim color fading ozonation were investigated in terms of the effects of time, pH and water content on their physical properties, which included chemical and crystalline structures, surface microstructure, yarns strength and elongation. It is found that, the cellulose in cotton and lyocell yarns has a loss of strength and elongation, while only slight impacts on their crystalline structures are observed. An aggregation and compact crystalline structure of PET prevents it from the decomposition of ozone, whose prevention may also benefit from its poor ability of moisture regain. As a result, synthetic materials, such as PET is recommended more than cellulose fibers to be used in ozone fading process. Meanwhile, such process should neither be employed on cotton, lyocell and other cellulose yarns at pH < 7 nor without paying attention to select a proper water content.