Elwood J. Gonzales

Kinetics of the Reactions of Ethyleneurea Derivatives with Cotton Cellulose Part II: The Cellulose—Bimethyloldihydroxyethyleneurea Reaction

The kineties of the reactions of cotton print cloth treated with 0.55 M solutions of 4.5-dihydroxy-1,3-bis(hydroxymethyl)-2-imidazolidinone (dimethyloldihydroxyethylene urea) in the presence of 0.03 M inorganic salt catalysts have been investigated. The present two-stage delayed-cure process for chemically modifying the performance of cellulosic fabrics depends on the significant differences in reactivities of cellu lose with methylol functional groups and with the hydroxyl groups of the urea derivatives. Specific reaction rate constants at 45, 55, 65, 75, and 85°C in the presence of ZnCl2, Zn(NO3)2, MgCl 2, and Mg(NO3)2 have been calculated by following the changes in nitrogen and formaldehyde contents and the changes in crease recovery properties of finished fabrics. These rates have been compared with those determined when cotton retets with an etherifying agent having ring hydroxyls only, as in the cellulose-dihydroxy ethyleneurea reactions, and with those determined when the etherifying agent has methylol hydroxyls only, as in the cellulose-dimethylolethyleneurea reactions. Enthalpies, entropies, and free energies of activation have been compared.

Physicochemical Study of the Cotton Cellulose— Dimethylolpropyleneurea Reaction1

Physical and chemical properties of cotton print cloth treated with 0.55 M solutions of 1,3-bis(hydroxymethyl)-2(1H)-tetrahydropyrimidinone (dimethylolpropyleneurea or DMPU) in the presence of 0.03 and 0.1 M inorganic salt catalysts have been determined. The kinetics of the reaction in the presence of 0.03 M catalysts have been investigated. Specific reaction-rate constants at 45, 55, and 65°C in the presence of ZnCl2, Zn(NO 3)2, MgCl2, and Mg(NO3)2 have been calculated by following the changes in nitrogen and formaldehyde contents. Changes in crease recovery properties of finished fabrics with changes in nitrogen and formaldehyde contents were also followed. Enthalpies, entropies, and free energies of activation at 45°C for the reaction have been calculated. Specific reaction-rate constants and activation parameters were compared with those values reported previously for the reactions of cotton with derivatives of ethyleneurea. Infrared spectral data of fabrics finished with DMPU were analyzed.

Urea-Phosphoric Acid Hydrolysis of Cotton Modified with N-Methylolated Ethylene Ureas

Native and mercerized cotton cellulose, modified with N-methylolated derivatives of ethylene urea, were examined before and after urea-phosphoric acid hydrolyses. Fine structural changes accompanying chemical reactions were evaluated by infrared absorption spectroscopy, x-ray diffraction, and electron microscopy. Final fabric properties and extent of restoration of original tensile properties after urea-phosphoric acid hydrolysis varied with the reagent applied and the lattice structure of the cotton control.

Urea-Phosphoric Acid Hydrolysis of Mercerized Cotton Modified with Methylated Methylolmelamine

Mercerized cotton finished with a methylated methylolmelamine (MeMM) responded differently to hydiolysis with urea-phosphoric acid (UPac) than did similarly finished native cotton. UPac hydrolysis did not affect dry and wet wrinkle recoveries of mercerized cotton, but caused reduction in dry recovery angles of the unmodified native cotton control. Treatment with MeMM produced specimens with equally high dry and wet wrinkle-recovery angles regardless of nature of the control fabric; behavior of MeMM-treated fabrics, when subjected to UPac hydrolysis, was influenced by nature of the control fabric. With MeMM-treated mercerized fabrics, each subsequent hydrolysis removed about one-half of the bound nitrogen and virtually all formaldehyde; it destroyed dry recoveries, but had little effect upon wet wrinkle-recovery angles. Each MeMM retreatment completely restored these properties in products from mercerized cotton, but resulted in only partial restoration of recoveries in products from native cotton. X-ray diffractions after MeMM-UPac treatments of mercerized cottons indicated retention of the mixed cellulose I and II lattice of the unmodified control while products from native cotton retained the cellulose I lattice. Infrared spectra indicated that reaction, with MeMM in both cases, proceeded with loss of adsorbed water and occurred preferentially at the primary hydroxyl of cellulose. Unlike products from native cotton, modified mercerized fabrics did not show a buildup of polymer on the periphery of fiber cross sections after an increasing number of MeMM-UPac treatments. Hence, homopolymerization was not indicated in the MeMM treatment of mercerized fabrics.

The Bonding of Phenols to Cotton with Zirconium Acetate

Zirconium acetate binds certain phenols to cotton to impart a high degree of rot resistance. Pentachlorophenol, pentabromophenol, methylenebis(p-chlorophenol), and p-hydroxyphenylmercuric chloride have been applied in this way, either as the free phenols or as their sodium salts. This type of treatment has advantages over the simple deposition of phenols on cotton in that the bound phenols are resistant to extraction with water and organic solvents and to removal by abrasion. Besides being rot resistant, the treated fabrics exhibited a good hand, noticeable water repellency, and increased breaking strength, although their tearing strength was usually decreased. Fabrics having appreciable flame resistance resulted when sodium pentabromophenate was applied. Increased weight, softness, and water repellency were obtained on boiling the treated fabrics in soap solutions. This is evidence of an exchange of stearate anions for acetate anions in the polymeric zirconium oxyacetate matrix on the fabrics.

Mixed Catalyst Systems for Reactions of Cotton with Dimethylolethyleneurea or Dimethyloldihydroxyethyleneurea

Substituted acetic acids or dibasic acids in combination with MgCl2 are active catalyst systems for the reaction between cotton and dimethylolethyleneurea (DMEU) or dimethyloldihydroxyethyteneurea (DMDHEU) at cure temperatures from 105-125°C. The reaction is primarily influenced by hydrogen ion concentration of the pad bath. Based on condi tioned wrinkle recovery of treated facrics, the order of increasing activity among the substituted acetic acid-Mgcl2 catalyst systems at 115°C in promoting the reaction of cotton with DMDHEU is as follows: acetic ≤ diethylaminoacetic < methylaminoacetic ≤ aminoacetic ≤ thiohydroxyacetic ≤ cyanoacetic ≤ hydroxyacetic acid. The order for the cotton-DMEU reaction is as follows: diethylaminoacetic ≤ acetic ≤ methylaminoacetic ≤ thiohydroxyacetic < hy droxyacetic ≤ aminoacetic ≤ cyanoacetic. Dibasic acids used with MgCl2 in the cellulose-DMEU reaction were more effective than either alone in increasing the amounts of bound nitrogen and formaldehyde and the wet recovery angles of the finished cottons. With DMDHEU, only the succinic acid-MgCl2 combination resulted in an increase in bound nitrogen over that observed with either catalyst used individually. With acids used singly or in combination with MgCl2, the pH of the pad bath was a primary factor in im proving wrinkle recovery with both DMEU and DMDHEU.

Differentiation of Catalyst Types in the Formaldehyde-Cotton Cellulose Reaction1

Differences in effectiveness between a Bronsted acid catalyst (hydroxymethane sulfonic acid) and two commonly employed Lewis acid catalysts (Zn(NO3)2 and MgCl2) on the pad-cure reaction of formaldehyde with cotton cellulose were determined in statistical experimental designs. The effects of each catalyst were followed by measured textile properties. Two methods for comparison of properties, one based on equal durable press appearance and a second based on equal conditioned wrinkle recovery angles, indicated that cotton reacted with formaldehyde in the presence of the Bronsted acid catalyst generally had superior resilience properties. Cotton reacted in the presence of the Lewis acid catalysts had better strength retentions at equivalent resilience by either method of comparison, and better abrasion properties by the method based on durable press appearance. Cotton reacted with formaldehyde and Lewis acid catalysts to a durable press appearance rating of 4.0-4.3 had better strength, abrasion, and wrinkle recovery angles than cottons reacted with formaldehyde in the presence of the Bronsted acid.

Applying Stepwise Multiple Regression Analysis to the Reaction of Formaldehyde with Cotton Cellulose

A fractional factorial design of experiments was formulated for the reaction of formaldehyde with cotton cellulose in the presence of hydroxymethanesulfonic acid in the conventional pad-dry-cure process. None of the 30 experimental treatments of cotton offered an attractive balance of durable press performance properties. Ap plication of multiple linear regression analysis to the experimental data resulted in equations relating the experimental variables to eight textile physical properties. These equations were used to calculate predicted values for each textile property that met or exceeded a minimum acceptable specification (MAS). The MAS was satisfied or exceeded (except for Accelerotor abrasion resistance) within small regions of profile plots for finishing reactions only at 140°C and in these cases, with decreasing area of regions for cures of 1, 3, 5, and 7 minutes. Experiments failed to confirm the validity of the regions of MAS. Correlation coefficients for the cellulose-formaldehyde- hydroxymethanesulfonic acid reaction were found to be lower than those for cellulose- DMDHEU reactions. These items are considered in some detail.

Free Radical Cross-Linking of Synthetic Polymers on Cotton Textiles

A variety of saturated thermoplastic polymers have been cross-linked as interfiber coatings on cotton fabric, without the cotton cellulose. the polymer with catalytic amounts of benzoyl peroxide or 2,4-dichlorobenzoyl peroxide on fabric at 100-165° C caused fixation of the coatings within a few minutes. Polyvinyl esters, acetals and ethers, and linear aliphatic polyesters were used. Copolymers of vinyl chloride with vinyl esters and with alkyl acrylates were also found applicable. The efficiency of polymer insolubility was 60-80% and was independent of the fabric used. whether cotton, glass, paper. Orlon,2 nylon, Dacron,3 or acetate rayon, Grafting of polymer to substrate apparently did not occur. Multiple layers of cross-linked coatings were readily formed. Application of poly(vinyl stearate) at add-ons of 4-30% imparted considerable water repellency to cotton and moderately increased the flex abrasion re sistance, while leaving air permeability, breaking strength, and tearing strength essen tially unchanged, Most of the polymer was located in interfiber spaces within individual yarns. Protection of interfiber bonding in cellulose from disruption by water occurred when cross-linked vinyl chloride-alkyl acrylate coatings were used.

Performance Properties of Cottons at Two Levels of Durable-Press and Conditioned Wrinkle-Recovery Angles

Polymerization-crosslinking reagents such as N-methylolacrylamide, N-methylol- methacrylamide, and N-methylolpolyethyleneurea (dp = 3) (NMP-2) and conven tional crosslinking agents such as dimethylolethyleneurea, dimethyloldihydroxyethyl eneurea, and formaldehyde were used to treat cotton twill fabrics. A concentration study with these reagents was carried out, and physical and chemical properties of the finished fabrics were compared. Strength and abrasion properties of treated fabrics at two levels of DP and conditioned WRA were also determined. The results indicated that the experimental reagents capable of undergoing polymerization as well as crosslinking within the cellulose substrate afford a superior balance of strength and abrasion properties. NMP-2 appears to be most stable to loss of formaldehyde among the polymer-forming reagents studied and most sensitive to loss of breaking strength from scorching following treatment with chlorine bleach.