The Reaction of Formaldehyde with Cellulosic Fibers

Abstract

The effects of an acid-catalyzed formaldehyde treatment on such mechanical properties as breaking strength and crease recovery have been determined for three cellulosic fabrics: cotton, Fortisan, and viscose rayon. Samples of these materials, treated under a selected set of conditions, were compared with three "controls": untreated fabric, fabric treated with distilled water under the conditions of the formaldehyde treatment, and fabric treated with the acid solution used in the formaldehyde treatment under the same conditions. The two-dimensional load-elongation behavior of the fabrics was investigated, and comparisons were made with the results of corresponding one-dimensional tests. The mechanical properties of single fibers and yarns taken from the variously treated fabrics were also measured.In general, cotton fabrics showed a deterioration in mechanical properties due to formaldehyde cross-linking with respect to the acid-treated control, while correspondingly, Fortisan and viscose rayon were improved by such treatment. In the case of cotton fibers and fabrics, it was found that the formaldehyde treatment had reduced the fiber and fabric elastic moduli with respect to the acid-treated control, although the formaldehyde treatment had also reduced correspondingly the fiber and fabric breaking strains. The deterioration in mechanical properties caused by hydrochloric acid was most marked in the case of Fortisan. It was found that generally the properties of single fibers, yarns, and fabrics are closely related.The improvement in crease recovery caused by the formaldehyde treatment was greatest for cotton, less for Fortisan, and least for viscose rayon. These different responses to the cross-linking reaction appear to be related to the different states of internal order of the three cellulosic fibers. Crease-recovery tests carried out on all the variously treated fabrics showed that marked improvements in crease recovery were usually obtained only with those treated at an initial pad-bath pH of 2.0, which indicates that a high degree of cross-linking of the hydroxyl groups in the amorphous regions of the fibers is necessary to achieve high degrees of crease recovery.

The Effect of Tension on the Properties of Resin-Treated Cotton Fabrics

“…There is thus, in mercerized cotton, an increased content of amorphous cellulose available for reaction with the resin, which should be expected to result in a lower level of treatment for a given resin add-on than is obtained with unmercerized cotton. A comparable situation exists in the responses of cotton and rayon to treatment with resins or formaldehyde: rayon has approximately twice the content of amorphous cellulose that cotton does, and rayon requires approximately twice as large an add-on of resin as cottons does to attain an equivalent irhprovenient in crease recovery ( 16,19 J . These results are in agreement with similar observations (increased strength, decreased resiliency) made by Orr Effect o f f abric.…”

Vapor-Phase Treatment of Cotton, Fabrics with Formaldehyde Catalyzed by Sulfur Dioxide1

“…Presumably, a portion of the strength loss results from hydrolysis of the cellulose by the acid catalyst [23,24]. A satisfactory process should employ an acid catalyst that causes the cross-linking reaction to go in a matter of minutes and, at the same time, avoids hydrolysis of the cellulose.…”

A Two-Dimensional Load-Extension Tester for Fabrics and Film

“…' Multidirectional test devices (mainly for rubberlike materials) have been developed by Ariano [ 2 J , Anderson ( 1 ) , Boonstra {3), and Treloar (5). A two-dimensional load-extension tester for woven fabrics has been described by Reichardt, Woo, and Montgomery [4] and used in an investigation of mechanical properties of formaldehyde-treated cellulosic fabrics by Woo, Dillon, and Dusenbury [6 ] .…”