Crosslinking Of Cotton Research Articles

Retraction of: Ionic crosslinking of cotton

Retraction of: Ionic crosslinking of cotton

DURABLE PRESS TREATMENTS TO COTTON, VISCOSE, BAMBOO AND TENCEL FABRICS

Durable press finishing processes are generally used in the textile industry to produce wrinkle-free fabrics and garments. A durable press finishing agent forms covalent bonds with cellulosic hydroxyl groups, thus crosslinking the cellulose molecules. The cross linking of cellulose increase creases resistance of treated fabrics, and in the case of cotton, reduces its strength. Crease recovery angle (CRA) and tensile strength are the two most important parameters which are used to evaluate the performance of the crosslinked cellulosic fabrics and garments. In this study, we investigated the effect of DMDHEU resin on the crosslinking of cotton, bamboo, tencel and viscose fabrics. Three levels of resin concentration and four levels of curing temperature were employed for crosslinking treatments. The curing time was kept at 4 min in all the cases. The results show that the crease recovery angle has improved in all the cases and the improvement was found to be excellent for viscose, With the exception of cotton, in all the other cases, the tensile strength was unchanged. Thus resin treatment is strongly recommended for bamboo, viscose and tencel fabrics as it is found to improve wrinkle resistance without causing any deterioration in strength.

Durable Press Finishing of Cotton Fabrics with Citric Acid: Enhancement of Whiteness and Wrinkle Recovery by Polyol Extenders

A durable press finisher formula based on citric acid (CA), featuring polyol extenders, can be made to compare favorably to dimethylol dihydroxyethyleneurea (DMDHEU) or 1,2,3,4-butanetetracarboxylic acid (BTCA) in whiteness and wrinkle recovery performance. Durable press (DP) finishing of cotton fabrics with CA has long been implicated by inferior resilience enhancement and appreciable fabric yellowing, which hinder the industrialization of the technique despite the obvious merits of CA being cost-effective, nontoxic, and renewable. In this research, glycerol was used as the model compound for investigateing the mechanism of polyol’s whitening effect and for obtaining the optimized curing conditions. Then a series of polyols were investigated as extenders for the cross-linking of cotton with CA. Performance indicators such as the wrinkle recovery angle (WRA), CIE whiteness index (WI), tear strength (TS) retention, and DP rating of the treated fabrics were correlated with curing conditions and the structures of the extenders. It was found that the whitening power of the extenders is directly related to the number of primary hydroxyl groups. It was also found that polyols containing both primary and secondary hydroxyl groups are more effective at enhancing the resilience of treated fabrics. By using xylitol as the extender, DP ratings of 3.8–3.9 were imparted to both white and dyed cotton fabrics finished with CA without significant yellowing or discoloration. The addition of the extender was also favorable to the durability of the DP effects so that a DP rating of 3.5 was retained after 20 washing and tumble-drying cycles. It was shown that by using biobased extender xylitol two major drawbacks of DP finishing of cotton with CA could be eliminated, presenting an essentially green alternative to DMDHEU.

Non-Formaldehyde Polyfunctional Crosslinking System for Cotton

Crosslinking of cotton with polycarboxylic acid, applied with catalysts based on phosphorus-containing inorganic acids, produces fabrics with excellent smooth-drying properties, which release no formaldehyde at any stage of preparation or on storage. If polycarboxylic acid has three or more carboxylic acid groups, the formation of such an anhydride can occur more than once and crosslinking of the cellulose molecule occurs. In our research work the use of an unsaturated bifunctional acid (maleic acid) and a phosphorus-containing inorganic compound (sodium hydroxyphosphinite) to obtain durable press finishing properties and flame retardant properties was studied.

Durable press finish of cotton via dual curing using UV light and heat

Continuous photografting/crosslinking of polyethyleneglycol dimethacrylate oligomers onto cotton using a water-soluble benzophenone photoinitiator was investigated. Photografting increased with increasing irradiation dose, oligomer concentration and photoinitiator concentration. Maximum grafting efficiency of DM 400 and 600 were 83% and 79%, respectively. The photografting increased the wrinkle resistance of cotton implying surface crosslinking of cotton. Both surface crosslinking and bulk crosslinking of cotton were accomplished via dual curing of a mixed formulation containing both a thermally curable component (BTCA/SHP) and a UV-curable component. The wrinkle resistance of the crosslinked cotton was found to be higher when cured by thermal curing after UV curing rather than by UV curing after thermal curing due to the facile post-polymerization of the UV active component. The presence of crosslinks in the dually crosslinked cotton was verified with FT-IR and thermogravimetric analysis.

IR spectroscopy study of cyclic anhydride as intermediate for ester crosslinking of cotton cellulose by polycarboxylic acids. V. Comparison of 1,2,4‐butanetricarboxylic acid and 1,2,3‐propanetricarboxylic acid

AbstractIn recent years extensive efforts have been made to use multifunctional carboxylic acids as formaldehyde‐free crosslinking agents for cotton to replace the traditional formaldehyde‐based N‐methylol reagents. In our previous research we found that a polycarboxylic acid esterifies cellulose through the formation of a five‐membered cyclic anhydride intermediate by dehydration of two adjacent carboxyl groups. In this research we used Fourier transform IR (FTIR) spectroscopy to study the formation of cyclic anhydride intermediates and crosslinking of cotton by 1,2,4‐butanetricarboxylic acid (BTA) and 1,2,3‐propanetricarboxylic acid (PCA). BTA and PCA form five‐membered cyclic anhydrides in the same temperature range. Both acids form the anhydrides at lower temperatures when a catalyst is present. When an acid molecule is bonded to cotton through an ester linkage, only PCA is able to form a second anhydride intermediate. We found that PCA is a more effective crosslinking agent, and it imparts higher levels of wrinkle resistance to the cotton fabric than BTA. Therefore, the formation of a five‐membered cyclic anhydride by a polycarboxylic acid accelerates the esterification of cotton by the acid. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2142–2150, 2001

Durable press finish of cotton fabric using malic acid as a crosslinker

It has been considered that malic acid,α-hydroxy succinic acid, could not form crosslinks in the cellulosic materials unless activated by other polycarboxylic acids such as butanetetracarboxylic acid or citric acid because there are only two carboxylic acids per molecule available for the formation of one anhydride intermediate. However we found that the dicarboxylic malic acid with sodium hypophosphite catalyst without the addition of other crosslinkers was able to improve wrinkle resistance of cotton up to 294° (dry WRA) and 285° (wet WRA), which is a measure of crosslinking level in cotton.1H FT-NMR, FT-IR and GPC analysis indicated the in-situ formation of an trimericα, β-malic acid with a composition of 1:3 through the esterification between hydroxyl group and one of carboxylic groups in malic acid during curing. The crosslinking of cotton was attributed to the trimericα, β-malic acid, a tetracarboxylic acid, which can form two anhydride rings during curing. The influence of crosslinking conditions such as concentrations of malic acid and catalyst, pH of the formulation bath, and curing temperature were investigated in terms of imparted wrinkle resistance and whiteness. The addition of reactive polyurethane resin in the formulation slightly increased the mechanical strength retention of crosslinked fabric coupled with additional increase in wrinkle resistance.

Durable press finishing of cotton with polycarboxylic acids. II. Ester crosslinking of cotton with dithiosuccinic acid derivative ofS-triazine

The preparation of an alternative polycarboxylic acid to replace the most promising but expensive crosslinking reagent butanetetracarboxylic acid (BTCA) was reported in Part I.1 Part II studies the efficiency of the crosslinking of cotton with the dithiosuccinic acid derivative of s-triazine (HDTST). Diffuse Reflectance infrared (DR FTIR) spectroscopy in combination with wrinkle recovery angle measurements (WRA) were used to analyse the efficiency of cotton cellulose crosslinking. Energy Dispersive X-ray analysis (EDX) of the polycarboxylic acid-finished cotton fabric was performed to study sulphur distribution. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 171–177, 1997

Crosslinking of Cotton with DMDMDHEU in the Presence of Sodium Chloride

A crosslinking treatment is reported for cotton fabric with dimethyldimethyloldihy droxyethyleneurea ( DMDMDHEU ) in the presence of various amounts of sodium chlo ride using a pad-dry-cure process. The crosslinked fabric and a control are studied for various physicochemical properties using standard methods. The distribution of cross links per anhydroglucose unit and the length of crosslinks are calculated from form aldehyde and nitrogen contents. Both number and length of crosslinks decrease with increased NaCl concentration in the pad bath. Self-condensation of resin and surface distribution ( on the treated fabrics ) are evident for fabric samples treated in the presence of sodium chloride. The relationships between various treated fabric properties are also considered.

Single‐step dyeing and finishing treatment of cotton with 1,2,3,4‐butanetetracarboxylic acid

AbstractA single‐step dyeing and finishing (SDF) process was developed to eliminate dyeing problems associated with cotton crosslinked by polycarboxylic acid such as 1,2,3,4‐butanetetracarboxylic acid (BTCA). This process consisted of several steps: (a) impregnation of the fabric by the bath containing BTCA, dye, and catalyst; (b) drying; and (c) curing at high temperature. Color strength (K/S) and dye fixation of cotton treated by the SDF process were excellent, especially with reactive dyes containing mono‐ or dichlorotriazinyl compounds and, in some cases, were higher than those of the sample dyed by a conventional batch process without finishing treatment. The presence of dye in the SDF process did not interfere with crosslinking of cotton. We believed that the reaction occurred between carboxyl groups of BTCA and s‐triazinyl groups in reactive dyes in the presence of imidazole and other catalyst. FTIR, Raman, and X‐ray fluorescence spectroscopies were used to confirm the mechanism of dye fixation. Elemental analysis also supported this mechanism. The SDF process can be an excellent way to dye fabric that also requires crosslinking treatment for smooth drying appearance. © 1994 John Wiley & Sons, Inc.

Alkali Metal Salts of Hydroxy Acids as Catalysts in Durable Press Finishing with Butanetetracarboxylic Acid

Alkali metal salts of hydroxy acids have been investigated as catalysts for esterification cross-linking of cotton with 1,2,3,4-butanetetracarboxylic add to produce cotton fabrics with smooth drying properties. Of the sodium salts of several acids studied, the sodium citrates produce fabrics with the best appearance properties. The sodium citrates serve both as donors of citric acid for cross-linking and of sodium ions for catalysis of the esterification of cotton cellulose by the two polycarboxylic acids. Although the use of citric acid as an extender for the more expensive butanetracarboxylic acid has been reported in non-formaldehyde finishing of cotton fabrics for smooth drying properties the catalyst used was sodium hypophosphite. Comparisons are made between fabrics finished with the phosphorus-containing system and the butanetetracarboxylic acid/sodium citrate systems. Textile properties, fabric whiteness, effect of pad bath pH, and extent of esterification are discussed.

Pore Structure and Dyeability of Cotton Crosslinked with DMDHEU and with DHDMI

The pore structures of cotton fabrics crosslinked to impart durable press performance with dimethyloldihydroxyethyleneurea (DMDHEU) and dihydroxydimethylimidaz olidinone ( DHDMI ) were compared using a reverse gel permeation chromatographic technique. Water soluble series of ethylene glycols and sugars were used to study the elution characteristics of columns prepared from these fabrics. From these data, dif ferences in pore size distribution in the control and modified cottons were elucidated. The results were compared to the receptivity of these cotton samples to the dye Direct red 81. Although crosslinking of cotton with either DMDHEU or DHDMI reduced accessible internal volume, samples reacted with DHDMI retained substantially more accessible internal volume across the entire range of pore sizes. Increasing add-on of DMDHEU further reduced the accessible internal volume. In contrast, the accessible internal volume in DHDMI-treated cotton was increased by additional add-on of this reagent. The trends with respect to relative receptivity to Direct red 81 generally related better to the quantity of residual large pores ( 17 Å) than to remaining intermediate pores ( 10 Å).

Effect of structural changes of cotton by acid hydrolysis and crosslinking on soiling and soil release

AbstractThe effect of acid hydrolysis (0.5N HC1 at 60°C for 5–90 min) on the soiling and soil release properties of cotton fabric before and after crosslinking was investigated. The effect of acid hydrolysis of crosslinked cotton under similar condition on the same properties was also undertaken. Crosslinking with and without nonionic softener was carried out using dimethylol dihydroxyethlene urea and magnesium chloide hexahydrate as a catalyst. Aqueous and nonaqueous oily dispersions of carbon black were used for soiling. Results of these studies disclosed that acid hydrolysis prior to crosslinking imparted aqueous and oily soil resistance to the cotton, particularly during the very initial stages of hydrolysis treatment. Crosslinking of cotton and acid‐treated cottons in the absence of softener accentuated soil resistance. The opposite holds true for crosslinking in the presence of softener. Short acid treatment of cotton before and after corsslinking decreased the ability of cotton to release the aqueous and oily soils. On the other hand, acid hydrolysis of crosslinked cotton improved aqueous and nonaqueous soil‐resistance provided that the duration did not exceed 30 min. Hydrolysis accentuated also the ease of oily soil removal, but aqueous soil release was adversely affected. The results were interpreted in terms of changes in the physical and chemical structures of cotton and crosslinked cottons brought about by acid hydrolysis.

Dependence of soiling and soil release of easy care cotton on factors‐controlling the finishing treatment

AbstractThe conventional pad‐dry‐cure method was used for effecting crosslinking of cotton with N‐methylol finishing agents under different conditions. Factors studied include nature and concentration of finishing agent and softener, type and concentration of catalyst, and curing temperatures. Variation of soiling and soil release characteristics of crosslinked cotton with these factors were investigated. The effect of finishing agent on aqueous soiling followed the order:Carbamate reactant‐fabric > Dimethylolethylene urea‐fabric > Dimethyloldihydroxyethylene urea‐fabric > Untreated fabric > Modified triazinone‐fabric ≥ Modified ethylene urea‐fabric. On the other hand, the effect of these finishing agents was to enhance the susceptibility of the fabric to oily soiling. Nevertheless, nature of the finishing agent governed the magnitude of this enhancement. Aqueous and oily soil release depended also upon the nature of finishing agent, soiling increased and soil release decreased by increasing finishing agent concentration. Type of catalyst exerted a considerable influence on aqueous and oily soil release without significantly affecting the degree of soiling. For aqueous soil release, the following order was found: Al2(SO4)3 · 18H2O > MgCl2 · 6H2O > urea nitrate > ZnCl2 · 6H2O > Zn(NO3)2 · 6H2O > urea phosphate > urea oxalate > NH4 · H2PO4 ≥ NH4Cl.A reverse order held good for oily soil release. Both aqueous and oily soil release were impaired by increasing catalyst concentration. Similarly, nature and concentration of the softener had no striking effect on soiling while they did on soil release. Raising the curing temperature from 80 to 140°C caused substantial reduction in case of soil removal of urea salts catalyzed‐crosslinked cotton samples while having the degree of soiling practically intact.

Studies of Some Basic Aspects in Easy-Care Cotton Finishing Part VI. Urea Nitrate Catalyzes Crosslinking of Cotton'

The feasibility of urea nitrate to catalyze crosslinking of cotton cellulose with N-methylol finishing agents was investigated under a variety of conditions. Urea nitrate proved to be an efficient catalyst for imparting easy-care properties to cotton fabric using the pad-dry-cure, pad-cure, and pad-mild-cure methods. Of particular interest were the results obtained with the pad-mild-cure method. A crease recovery as high as 280° could be achieved by mild curing of the fabric at 70°C for 5 min with only ca. 11 % loss in strength properties. The finishing agents used were commercial types based on carbamate reactant, dimethyloldihydroxyethyleneurea, dimethylolethyl eneurea, modified triazinone reactant, and modified ethyleneurea. The pad bath was stable up to 24 hours.

Soiling, Staining, and Yellowing Characteristics of Fabrics Treated With Resin or Formaldehyde

Cotton and 50/50 polyester/cotton fabrics, untreated and with four formaldehyde crosslinking treatments and two resin finishes, were soiled with oily and nonoily soils and an oily stain. Extent of soiling, ease of soil and stain removal, and the development of yellowness were determined after repeated laundering in a Launder-Ometer. Soiling and soil removal were influenced more by type of soil, fiber content, process of producing crosslinks, and catalyst than by the chemical composition of the crosslinking agent, although chemical composition did produce some effects. Development of yellowness of untreated and crosslinked fabrics during laundering was attributed to swelling of cotton fiber and cotton content of polyester/cotton blend fabrics. Cross-linking of cotton and cotton/ polyester fabrics by a pad-dry-cure process retarded the development of yellowness. Yellowness developed in both oily and nonoily soiled fabrics. Yellowness was not related to amount of soil on the fabrics.

The Mechanism of Catalysis in the Crosslinking of Cotton with Formaldehyde

Crosslinking of cotton cellulose with formaldehyde by the pad-dry-cure process has been studied kinetically. The reaction is catalyzed by hydroxonium ions, and this catalytic reaction accounts for more than 98% of all crosslinks formed. MgCl2 and mixtures of MgCl2 and tartaric acid have no detectable, direct catalytic effect but owe their activity to the fact that they bring about an increase in the concentration of hydroxonium ions under curing conditions.

Comparison of Catalytic Activities and Textile Mechanical Properties Observed in the Crosslinking of Cotton with Highly Active Catalysts

Nine metal chlorides and mixtures of these salts with tartaric acid are compared with hydrochloric acid with regard to catalytic activity in crosslinking cotton fabrics with formaldehyde by the pad-dry-cure process. The sequence of catalytic activity can be rationalized by the hard/soft concept of acids and bases. When highly active catalysts are applied, the relation between dry crease-recovery angle and tensile strength is significantly improved for DMEU-cross-linked fabrics but only marginally improved when formaldehyde is used as the crosslinker.

Crosslinking of Cotton through Graft Copolymerization

Fabric samples were grafted with binary and ternary mixtures of selected vinyl monomers along with acrylamide onto cotton using ceric ammonium nitrate as catalyst from aqueous solution or emulsion, and subsequently polyacrylamide grafts were methylolated in situ and crosslinked. Except in the case of acrylamide-acrylonitrile treatment, finished fabrics show good wrinkle-recovery properties accompanied by satisfactory retention of breaking- and tear-strength and also very much improved resistance to abrasion. The finish is suitable for the deferred-cure process with minimum evolution of formaldehyde. When the above-mentioned uncrosslinked grafted samples are crosslinked through N-methylol crosslinking agents, improvement in wrinkle-recovery properties are accompanied by usual losses in strength and abrasion resistance. However, when ternary mixtures containing ethylacrylate, acrylamide, and acrylonitrile are grafted at higher polymer add-ons, and fabric is crosslinked through the conventional crosslinking agents, very good abrasion-resistance properties along with good strength retention are achieved. In the reverse process— i.e., where samples are first crosslinked through polyacrylamide grafts and then further grafted with ethylacrylate alone or in combination with other monomers—abrasion properties are markedly improved, while wrinkle-recovery properties are only moderate.

Crossliking Cotton in an Unheated Dehydrating Atmosphere

A new approach to the crosslinking of cotton was investigated. Finished fabrics with wrinkle resistance properties similar to those of damp cured fabrics were produced by treatments in which the curing operation takes place over an extended period of time in an unheated dehydrating atmosphere. The crosslinking reaction, which produces wrinkle resistance, is promoted by removal of water from the fabric by contact with dried air at room temperature. The in fluence of changes in various parameters of the treatment was explored. Dimethylol methyl carbamate, dimethylol dihydroxyethyleneurea, and formaldehyde were used as crosslinking agents with hydrochloric acid and sulfuric acid as catalysts. In dehydration curing, deswelling of the fiber during reaction is evidently slow and not as complete as in conventional curing at high temperature.