Description

This test method is used to determine the fixation properties of disperse dyes on polyester/cellulose blends as a function of fixation conditions. The variable described herein is temperature; however, variations in time and/or concentration of dyes and/or auxiliaries may be studied by this method.

Principle

The dye is padded onto the blend fabric at a specified concentration; the fabric is dried and the dye is fixed by exposure to controlled conditions of time and temperature. The cotton portion of the blend is dissolved in concentrated sulfuric acid followed by neutralization and thorough rinsing.

The reflectance values of the dyed fabrics, exposed to several fixation conditions, are determined by spectrophotometry and the concentrations of dye relative to the heaviest dyeing (as 100%) are evaluated by applying the Kubelka-Munk function (K/S). These results express the relative dye fixation for a particular set of dyeing conditions. Alternatively, the dye on the fabric can be extracted with a suitable solvent and the concentrations of the dye determined by transmittance spectrophotometry. When the dye concentrations on the fixed samples are compared to the corresponding concentration on a padded but unfixed sample, a measure of the true dye fixation, as a function of applied dye, may be obtained.