Thesis Details

Thesis Title: An evaluation of near infrared reflectance analysis in determining the effects of slasher variables on desizing nylon filament yarns
Thesis Author: Kimila K. Cope
Abstract: The dyeing process for any fabric in the textile industry is considered to be the most costly process. It is essential, therefore, that fabric be properly prepared prior to the dyeing operation. Failure to supply dyers with properly prepared fabric can result in numerous defects, including shade variations. Research has revealed that these shade variations can result from any slight irregularities in the preparation process, including ineffective size removal. Limited research has been published in the area of how slashing affects removability of sizing materials. This thesis focused on the effects of slasher speed, slasher dry can temperatures, size type, size add-on, and yarn denier on desizing nylon filament yarns sized with acrylic sizes. Two yarns, 70 and 200 denier nylon 66 (both 34 filaments), were used throughout the experiment. Near Infrared Reflectance Analysis was utilized to develop equations capable of determining size add-on for both yarns sized with polyacrylic acid and a polyacrylate dispersion. A total of 72 experimental conditions were slashed and evaluated for ease of removability in the desize process. Both yarns and sizing agents were slashed at varying levels of temperature, size add-on, and speed. The results of this investigation indicate that yarn denier has a pronounced effect on the desizing process. As yarn denier increased, removability of the size became more difficult. This may be the result of the spacing differences between individual filaments in the yarn bundle. For 200 denier yarns, the individual filaments do not pack as tight as in 70 denier yarns, which allows the size to better penetrate the bundle. As penetration into the bundle increases, it is speculated that removability of the sizing agent becomes more difficult. The size type also had an effect on desizing. Two sizes, polyacrylic acid and a polyacrylate dispersion, were used in this study. The polyacrylate dispersion is more difficult to remove because it is a water dispersible compound whereas polyacrylic acid is water soluble. A dispersion consists of finely divided particles, not solubilized, and therefore would be more difficult to remove in the desizing process. Those findings associated with dry can temperatures were of the most interest. For 200 denier yarn slashed with the polyacrylate dispersion, the removability of the sizing agent became increasingly more difficult as dry can temperatures increased in slashing. with the assistance of Near Infrared Spectral Analysis, it was found that increasing temperatures serve to further polymerize the sizing agent as well as increase the bond formation between the size and the yarn.