Thesis Details

Thesis Title: The effects of solvent based carriers on the dyeing and physical properties of Nomex fabric
Thesis Author: David Vlaservich
Abstract: Nomex, which was introduced by E.I. DuPont de Nemours and Company in the late 1940's, was developed to meet the need for improved fiber durability and functionality at high temperatures. Nomex is a non-melting polymer which does not support combustion, only begins to char at 700 °F and has been found in end-use products ranging from hot gas filtration bags to productive clothing. A major problem with Nomex is that it is extremely ~ difficult and expensive to dye. The inherent chemical structure and high glass transition temperature prevents most dyes and carriers from penetrating into the compact structure. Currently, the recommended dyeing procedure for Nomex is limited by the necessity for high concentrations of carrier, high temperature for a prolonged period of time, difficulty in removal of the carrier, and a decrease in the flame resistance characteristics due to residual carrier in the fiber. Because of the difficulties in dyeing Nomex, many companies are having to buy solution dyed Nomex to meet the appropriate specifications for the desired end-uses. The buying of solution dyed Nomex increases the price of the final product, eliminates the capabilities for style and color changes, and eliminates the ability for quick response. This work evaluated eight solvents, at two dyeing times, two concentrations of solvent, with and without t he addition of sodium nitrate, and were dyed according to t he aqueous dyeing procedure. The dyeings were conducted on a single primary dye shade and on a trichromatic dye shade . In addition, the solvents were evaluated by treatment o f the Nomex prior to dyeing. Results from the aqueous dyeing procedure indicated the solvent Acetophenone (Dymex) gave the highest increase in depth of shade followed by Methyl Benzoate and N-Cyclohexyl- 2-Pyrrolidone. In addition, longer dyeing times, higher concentrations of solvents, and the use of sodium nitrate added to the dyebath allowed for a significant increase in dye uptake. The remaining solvents, DMF, DMSO, Sulfolane-W, Antiblaze 19T, and Antiblaze 100 had virtua lly no effect on increasing the depth of shade. The solvent pretreatment prior to dyeing revealed t hat the treatment of Nomex with the solvents DMF, DMSO, and Methyl Benzoate significantly increased the depth of shade to near that of the dyeing conducted by the aqueous process using the solvent Acetophenone (Dymex). Further research of the pretreatment procedure may produce a dyeing procedure which overcomes the disadvantages of the current aqueous dyeing procedure.