REMOVAL OF CELLULOSIC CROSSLINKS UNDER NONACIDIC CONDITIONS

摘要

The primary purpose of this research was to determine the source of strength loss exhibited by cellulose fabrics which have undergone a crosslinking procedure.;In order to avoid the potentially degradative effects of acidic crosslinking and decrosslinking systems, the crosslinks were inserted and removed under alkaline conditions. A plain weave, desized, scoured, 100 percent cotton fabric was used. There were four treatment levels: the cotton fabric serving as its own control, cotton treated with a 1 percent sodium sulfite solution, cotton treated with a 10 percent dimethoxymethylurea, 1 percent sodium sulfite solution, and cotton which was treated with 5 percent sodium hydroxide to remove the crosslinks which had been introduced by the dimethoxymethylurea, sodium sulfite system. All samples were impregnated to 100 percent wet pick up (the control sample was wet out with water), allowed to air dry, and then cured at 150(DEGREES)C under vacuum. Fluidity, crease recovery, tear, tensile, and abrasion resistance data were developed and analyzed.;Crease recovery data confirm that the fabric has undergone both.;a crosslinking and a decrosslinking procedure under alkaline.;conditions. Tear and tensile strength data confirm that strength is.;lost when the finish is present and that the strength is restored, for.;the most part, when the finish is removed. Because restoration of.;the original strength properties is possible when the crosslinks are removed, it is concluded that the strength loss exhibited by cross-linked fabrics is due to the rigidity imparted to the cellulose molecules by the crosslinks.;This study also investigated the mechanism for the removal of.;cellulose crosslinks under alkaline conditions. Nuclear magnetic.;resonance scans indicate that a sodium borohydride, sodium.;hydroxide system for cellulose crosslink removal does not proceed.;via an azomethine intermediate as was hypothesized. Instead, it is believed that a simple alkaline hydrolysis occurs at the.;H O.;(VBAR) (VBAR) (VBAR).;- N - C -.;site resulting in the production of ammonia and carbonate. It also has been shown that sodium hydroxide is an effective decrosslinker in the absence of sodium borohydride.