Distribution of Crosslinks in DMDHEU-Treated Fabrics from Measurements on Warp and Fill Yarns

Abstract

Dimethyloldihydroxyethyleneurea (DMDHEU) was applied to cotton fabrics via immersion padding followed by fast (I-FD) and slow (I-SD) drying and via lick roller (LR20, LR35) and foam (FM20, FM35) applicators at 20% and 35% wet pickups. The fraction of cuene-soluble cellulose, distention index ( DI), water of imbibition ( WI), and moisture regain ( MR) were determined on the fabric or the separated warp and fill yarns to elucidate the effect of processing conditions on crosslink distribution. The slowly dried fabric served as the standard for uniformity. Samples were compared at the same level of bound nitrogen. High DIs, WIs, and MRs were associated with a less uniform crosslink distribution at the same overall crosslink density. Uniformity of crosslink distribution was found to decrease in the order I-SD > FM35 > LR35 > I-FD > FM20 > LR20. The fraction of cuene- soluble cellulose increased with increasing bound nitrogen in the LR20 samples, whereas the WI and MR of these fabrics exhibited U-shaped behavior. These trends are attributed to decreasing spreadability of liquor with increasing reagent concen tration. The result is that progressively larger portions of the cotton fabric are left untreated. Foam application at the 20% pickup level resulted in enough penetration to the backside of the fabric to impart cuene insolubility at all but the lowest DMDHEU add-on level. Indications are that the spreading mechanism for foam is substantially different from and more efficient than that for the liquid film from the lick roller. Crosslink distributions differed in the warp and fill yarns in all but the I-SD samples.