The adsorption of a commercial stainblocker on nylon 6.6

The adsorption of a commercial stainblocker onto nylon 6.6 fibers of 45 amino end group (AFC), and also 70 AEG, was found to increase with decreasing application pH, indicating that ion-ion interaction contributed to stainblocker-fiber substantivity. Uptake of the stainblocker also increased with increasing application temperature, which is attributable to the higher kinetic energy of the stainblocker molecules and the greater extent of the fiber-swelling operative at the higher temperatures. Adsorption of the stainblocker on to 45 AEG fiber increased with decreasing liquor ratio, possibly as a result of stainblocker aggregation, but in the case of 70 AEG nylon fiber uptake, slightly decreased with decreasing liquor ratio. From the finding that uptake of the stainblocker onto undyed 45 AEG and 70 AEG nylon 6.6 followed a Brunauer-Emmett-Teller mechanism, it was postulated that adsorption involves the formation of multilayers and that forces other than ion-ion contribute toward stainblocker-fiber interaction. This postulate gained support from the observation that although the presence of 1% omf dye on the two types of fiber reduced the extent of stainblocker uptake, the mechanism of stainblocker adsorption onto both substrates was unaffected. (C) 2000 John Wiley & Sons, Inc.