Cotton Cross-Linked at Various Degrees of Fiber Swelling

Abstract

Wet and dry density measurements were made on a wide variety of wash-and-wear cotton fabrics and some interpretations of these values are given. Methylenated cotton was selected for more extensive fundamental study because of the simplicity of the formaldehyde cross link and the fact that formaldehyde can be reacted with cotton under greatly different conditions. Formaldehyde was used to cross link cotton print cloth at various degrees of fiber swelling by reacting in systems ranging from completely aqueous to anhydrous using hydrochloric acid as catalyst. The amount of water in the system at the time of reaction is related to the extent of fiber swotting. The extent of swelling at the time of cross-linking and the extent of cross-linking influence wet density, which may be considered to be a measure of the water swellability of a fiber. Cross-linking tends to fix or stabilize a fiber in a given state of swelling: the stabilization is more effective when the cross-linking is done in nearly anhydrous systems. The state of swelling at the time of cross-linking modifies moisture regain, water of imbibition, dyeabitity, and wet and dry wrinkle recovery. There seems to be an optimum water content in the reaction system at the time of cross-linking for maximum dry and wet wrinkle recovery. As the water content in the reaction system is increased beyond the optimum, the amount of dry wrinkle recovery becomes much less than wet wrinkle recovery. This phenomenon leads to vastly different wash-and-wear ratings of fabric.A mechanism is presented diagrammatically to explain wet and dry wrinkle recovery. The mechanism is based upon hydrogen-bond cross links, covalent-bond cross links, and the position of the two types of cross links.AL.'FHOUGH wrinkle resistant cotton fabrics have heen known for about 30 years, many of the basic principles for imparting wrinkle recovery are not too well understood. The wrinkle recovery and washand-wear characteristics of a textile are affected by its construction and by the construction of the yarns of which it is composed. However, the properties of the fiber which make tip the yarn and fabric have, perhaps, an even greater influence on wrinkle recovery and wash-and-wear properties. Cross-linking within the fiber seems to have been accepted by most researchers as the hasic requirement for wrinkle recovery. It provides an excellent way of changing many of the properties of cotton fiber. The physical properties of cross-linkeci goods are quite well known, but the principle of producing physical changes with -----.-----.. cross links within the microstructure of the fiber, which is actually responsible for the fiber properties, is not too well defined. Differences have been observed between the wrinkle recovery of cotton fabrics finished by the pad, dry, and cure process and the wrinkle recovery of fabric finished while swollen in mercerizing strength alkali solution. The first of these processes, which is often thought of as reacted in the collapsed state, imparts wet and dry wrinkle recovery....

Crosslinking Cotton Fabric with DMDMDHEU Using Water /Methanol Mixtures as Solvents

“…Samples obtained from the H20/MeOH = 40/60 mixture show greater WCRA values than those from the 100% methanol and water at the same TSR value; in addition, samples from the 100% methanol show greater WCRA values than those from the 100% water at the same level of TSR. Higher WCRA values may be attributed to the highly swollen state of the crosslinked fiber or fabric [ 13,15,16 ] . Table II on the number of crosslinks per anhydroglucose unit (CL/AGU ) and length of crosslinks obtained using the method of Frick et al [ 3,4 indicate that in all cases, both increase as the concentration of the resin in the bath increases.…”

Physical Properties of Cotton Treated by Pad-Dry-Cure, Mild-Cure, Poly-Set, and Wet-Fix Processes

“…The high crease recovery for the wet-fix fabric with low recoveries in the fibers must be attributed to joint actions of several factors. Fibers cross-linked when swollen have been observed in other treatments to have high recoveries of a wet fabric ( 10] . The cross links formed during a cure when the moisture is very low has a high dry recovery, but only a medium wet recovery.…”

Investigations on the Chemical Constitution of Cotton Cross-Linked With Formaldehyde

“…They include moisture regain [5,30] , infrared deuteration [11. 12, 13, 16, 28], formylation [ 18,21,24], iodine sorption [26], acid hydrolysis [20,23,25,27], and periodate~oxi-dation [ 2,6,29 ] . ' A series of cotton and partially methylated cotton fabrics have been examined by these techniques and the results obtained have been compared.…”

“…Cotton cross-linked with f6rmaldehyde is particularly suitable for such an investigation since the correlations between the methods of application and the textile mechanical properties have been thoroughly investigated [3,7,8,9,24] . Also, in three previous investigations [1,2,25,34] , results on the reactivity ratio of formaldehyde with the hydroxyl groups in the 2-,-3-, and 6-positions of the anhydroglucose unit are described.…”