SHADING OF POLYAMIDE 6.6 AFTER MULTI WASHING PROCESS AND INVESTIGATION OF CHEMICAL CHANGES ON FABRIC SURFACE

When white fabrics are subjected to repeated washing process with home type laundry detergent, whiteness is decreased and yellowing or graying become evident. Post-wash protection of fabric whiteness is provided with various additives such as fluorescent whitening agent, shading dyes in detergent contents. The aim of this research is to investigate the usage of shading dyes for preventing the complaints of graying/yellowing occurring after multi washing process in polyamide fabrics. Chemical effects over the multiwashed polyamide fabrics were explained by using standard test methods. The whiteness index of fabrics (WI CIE) was measured by spectrophotometer. Post-multiple washing effects were evaluated by loss of strength, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). According to the results, detergent formulation including Disperse Violet 28？ shading dye showed better whiteness index in spite of having 10% bleaching system than detergent formulation including Direct Violet 9？ shading dye having 12% bleaching system. Statistical evaluation of bursting strength showed that the same strength losses on fabrics in both detergent formulas occurred. Calcium carbonate was determined on polyamide fabric surface by FTIR and XPS results supported this finding