Release behavior and kinetic evaluation of formaldehyde from cotton clothing fabrics finished with DMDHEU-based durable press agents in water and synthetic sweat solution

Abstract

The durable press-finished cotton fabrics were prepared with dimethylol dihydroxy ethylene urea (DMDHEU) and methylated DMDHEU, and tested for formaldehyde release in distilled water or synthetic sweat at pH 5 or 8 to simulate the extraction of formaldehyde by sweat under similar wearing conditions. The release mechanism of formaldehyde was studied and compared using three diffusion kinetic models. The effect of release conditions and finishing process on the formaldehyde release was also investigated. The results indicated that the release process of formaldehyde from the finished fabric includes a burst release phase and a slow release phase, which is explained by five different sources. The formaldehyde release mechanism followed the Fickian mode, and could be described by Higuchi, Double phases and Korsmeyer–Peppas kinetic equations, respectively. Higher formaldehyde release was found at pH 8 than that at pH 5. Formaldehyde showed a lower release rate in synthetic sweat solution than that in water under the same conditions. Increasing water volume or temperature enhanced the formaldehyde release, suggesting that a high sweat rate and skin temperature may accelerate the formaldehyde release. When finishing the fabrics, a higher concentration of finishing agent and the addition of softener accelerated the formaldehyde release. However, increasing catalyst concentration and curing temperature could reduce the formaldehyde release. It is concluded that formaldehyde release can be effectively reduced by optimizing the durable press finishing process of cotton fabrics, thus possibly decreasing risk of allergic contact dermatitis from formaldehyde in textiles.