Influence of Mercerization and Crosslinking of Cotton Fabrics on Dyeing Kinetics of Direct Dyes from Finite Baths

Abstract

Dyeing of cotton fabrics treated with dimethyloldihydroxyethyleneurea and triethanolamine is discussed. Adsorption time curves from finite baths of untreated, mercerized, and crosslinked cotton print cloths have been studied. Mercerization did not change heterogeneous diffusion resistance but increased adsorption equilibrium constants, dyeing affinities, and diffusion coefficients. Maximum dyeing capacities of mercerized cotton were lower. Crosslinking reduced most of the kinetic constants (rate constants, structural diffusion resistance constants, maximum dyeing capacities, activation energies, and diffusion coefficients). Triethanolamine additive enhanced the kinetic constants and the dyeabilities of crosslinked cotton fabrics. The results indicated that in the crosslinked cotton, triethanolamine reacted preferably with the crosslinks and not with the remaining free reactive groups of cotton fabric.Crosslinking by dimethyloldihydroxyethyleneurea (DMDHEU) reduces the equilibria and dyeing rates of cotton or other cellulosic materials [7,9,10]. On the other hand, mercerization increases the dyeing rates. When the cotton fabrics are crosslinked and treated with triethanolamine (TEA), nitrogen content and dyeability increase [ 1 ] . In order to better understand the effect of crosslinking by DMDHEU and TEA on dyeing kinetics from finite baths, we have studied the time curves under different dyeing conditions using the following diffusion kinetic equation [2][3][4][5] :where a is the adsorption of the dye on cotton in time t, a~ is the equilibrium adsorption at t -oo , k is the specific rate constant, Co is the concentration of cotton in a finite bath, and n is the structural diffusion resistance constant. The half-life of dyeing is then From these constants, we have determined other kinetic constants (maximum adsorption capacities ~B, adsorption equilibrium constants Ko, diffusion coe~-cients D, activation energies AE*, enthalpies 011, and exhaustions a ) [ 2 ] . By means of these kinetic parameters, we can predict the structural changes of cotton fabrics and the dyeing kinetic profiles from finite baths under different conditions ( dye and cotton concentrations and temperatures).We determined the constants of Equation 1 using the computer mathematical regressions of the time curves [3]. Graphical determination [2] was less accurate but agreed well in the limits of errors with the computer analysis. The maximum adsorption capacities, the adsorption equilibrium constants, the acti-. vation energies of dyeing, and the apparent enthalpies were determined statistically from two or more time curves with two or more dye and cotton concentrations and two or more temperatures as described previously [ 2 ] . The apparent diffusion coefficients were calculated by comparing Equation 1 with the integrated Fwk's diffusion equations [2, 6, 12] under the assumption that cotton fibers are cylinders:All these kinetic constants obtained from the time curves were a useful tool for elucidating the dyeing mechanism and some structural ...

Pore and crosslinking structures of cotton cellulose crosslinked with DMDHEU‐maleic acid

“…From those results of linear relationships, we believe that the use of the diffusion kinetic equation reported by Chrastil et al 7,8 to study the equilibrium absorption (a e ), rate constant (k'), and structural diffusion resistance constant (n, the index of the pore structure) of the various treated cotton fabrics is suitable. Several data obtained from the dyeing kinetics of eq.…”

Crosslinking of Cotton Cellulose in the Presence of Alpha-aminoacids Part III: Pore Structures

“…Those figures reveal the linear relationships between the logarithmic values of the dye (direct red 81) absorption (log a) under the different temperatures and the logarithmic val-TRJ TRJ ues of the time intervals of dyeing (log t) over the initial dyeing time duration. From these linear relationships, we concluded that the use of the diffusion kinetic equation reported by Chrastil et al [8,9] to study the equilibrium absorption (a e ), rate constant (k′), and structural diffusion resistance constant (n, the index of the pore structure) of the various treated cotton fabrics was acceptable. Figure 3(a)-(c), respectively, show similar linear relationships for the rates of dye absorption of the cotton crosslinked with DMDHEU alone, DMDHEU-aspartic acid, and DMDHEU-glutamic acid, which were obtained from the samples dyed with direct red 80 at different temperatures.…”

“…The higher dye absorption values for the DMDHEU-alpha amino acids were likely to be caused by the different pore structures of the crosslinked fabrics. It is well known that the crosslinking reaction between alpha-amino acid and cellulose is significantly lower than that between DMDHEU and cellulose; however, the reaction between the amino group of amino acids and the Nmethylol group of DMDHEU was significantly higher than that between the N-methylol groups of DMDHEU [9,13]. The degree of condensation reaction between DMDHEU and alpha-amino acid must be different from that of self condensation of DMDHEU, and the pore structure of the treated fabrics would be different from each other.…”

Crosslinking structures and dyeing kinetics of cotton cellulose treated with a steeped process

“…Direct Red 81 with a molecular weight of 676 g/mol was used to study the pore structures of the steeped-procedure-treated fabrics. We studied the pore structure by using the following diffusion equation: 6,7 a ϭ a e ͓1 Ϫ exp͑ Ϫ kC 0 t͔͒ n ϭ a e ͓1 Ϫ exp͑ Ϫ kЈt͔͒ n (1) where a is the absorption of the dye on cotton in time t, a e is the equilibrium absorption at t 3 ϱ, k is the specific rate constant, kЈ is the rate constant, C 0 is the concentration of cotton in a finite bath, and n is the structural diffusion resistance constant. The higher n is, the larger the pore size is of the treated fabric.…”

“…From the results of the linear relationships, we believe that the use of the diffusion kinetic equation reported by Chrastil and coworkers. 6,7 to study the equilibrium absorption, rate constant, and structural diffusion resistance constant (the index of the pore structure) of the various treated cotton fabrics is suitable. Several data obtained from the dyeing kinetics of eq.…”