Strength Losses and Structural Changes in Cotton Fabric Crosslinked with Dimethylolethyleneurea 1

Abstract

Losses in tensile and tearing strengths and other physical properties of cotton fabric given durable-press finishes have been attributed to factors arising mainly from the crosslinking of the cellulose molecule. This conclusion was deduced from the results of textile testing of the treated fabrics. In order to define the sources of these strength losses, a study was made of cotton fabric treated with dimethylolethylene urea and a zinc nitrate catalyst in a commercial manner, but with varying times of cure. Heretofore unobtainable molecular parameters of durahle-press cotton fabric were estab lished from solubilized samples. Correlations made between physical properties of the fabric and the fine-structural features of the fiber, both of which were measured, estahlished the fractions of losses arising from molecular degradation and from crosslink embrittlement as a function of the extent of cure. In the shorter cure times, the predominant strength loss came from crosslink embritttement, but this proportion dropped rapidty and molecular degradation became the major source. Changes in degree of polymerization suggest that the catalyzed crosslinking reaction produces a limited chain extension of the cellulose molecule which becomes evident after removal of the crosslinks.