Natural dyeing of recycled cotton and polyester-cotton blended yarns with chitosan biomordant

Abstract

Studies on recycling and natural dyeing have gained great importance for the textile sector, which creates the most pollution and causes significant problems. Chitosan and its forms with their versatile properties are of great importance for many industrial areas from textiles to medicine. In this study, the effects of different-molecular-weight-chitosans as biomordants on the natural dyeing of recycled cotton and cotton-polyester yarns were investigated. The colorimetry results showed that while chitosan increased the yellowness and chroma of the colors, it decreased their redness, it is caused the colors to shift towards orange-yellow region. This change could be mitigated by changing the conditions under which the dyeings were conducted. Medium molecular weight chitosan was more effective in these changes than the low ones. Although there were changes in the angles of the colors, it was observed that the color strengths increased with the rise of the chitosan concentration. Although higher color strengths were obtained from dyes without chitosan, the increase in color depths with the increase of chitosan concentration revealed that chitosan could be used as a mordant. The good washing fastness obtained were explained by the low color strengths or the strong binding of chitosan and dye to the fiber.