No abstract

The reactions of various commercially available epoxides with cotton cellulose in the presence of sodium hydroxide have been investigated at 25°, 50°, and 95° C. The effects of solvents and alkali content of the yarn steep on the epoxy add-on have been studied.

Butadiene diepoxide (BDE), the meso‐1,2,3,4‐diepoxybutane, may be added to cotton cellulose with a variety of catalysts and conditions at room temperature. A slow addition of BDE from nonpolar solvents to yarns pretreated with alkali resulted in weight gains which were proportional to the activity of hydroxyl ions used in pretreatment. For a given hydroxyl ion activity, percentage weight gains of BDE varied directly with time of reaction. Add‐on of BDE has been shown to be proportional to the product of hydrolyzed BDE and molarity of the hydroxyl ion in the dilute alkali. It has been shown that slow addition of epoxide from carbon tetrachloride solution to cotton fabric impregnated with dilute alkali, natural salts, or alkaline salt solutions produces a fabric of good dry and wet crease recovery. Rapid addition of epoxide to fabric by the use of more concentrated alkali or elevated temperature showed excellent wet, but no dry, crease recovery. Hydrogen ion catalysis of the BDE–cotton reaction is very slow and, in the case of acetic acid, is without effect. With sulfuric acid, only mediocre wet crease recovery is produced a t room temperature. Catalysis with zinc fluoborate, methanolic solutions of BDE, and curing temperatures of 75–125° resulted in excellent wet and dry crease resistance a t weight gains of less than 2%. All methods of BDE addition to cotton fabric that produce good dry crease recovery cause a lowering of tearing and breaking strengths. There is little change in tensile properties when only wet. crease resistance is imparted. This suggests that profound physical changes in the fine structure of cellulose result from mild chemical action with a water‐soluble diepoxide. Recovery from deformation of cotton fibers in the wet and dry states (crease recovery) has been attributed to intermolecular covalent crosslinking of anhydroglucose unit hydroxyls by the diepoxide and, in particular, to crosslinking of hydroxyls on carbons 2 or 6, with a resultant diminution of interchain slippage. Fibers that exhibit only wet crease recovery are believed to have a minimum of covalent crosslinks and to be hydroxy cellulose monoethers of the epoxide or graft polymers of the same, which prevent slippage of chains only when wet and swollen (possibly by entanglement).

Four diepoxides, namely, the diglycidyl ether of 1,4-butanediol, meso-butadiene diepoxide, Eponite 100, and vinylcyclohexene dioxide have been applied to cotton print cloth (80 X 80) from methanolic and aqueous solutions in the presence of zinc fluoborate as catalyst. Physical properties imparted to cotton by these diepoxides under various conditions of reaction and cure have been evaluated. Data are presented to show varia tion of fabric properties with mole ratios of diepoxide: Zn(BF4) 2: AGU ( anhydroglucose units of cotton cellulose). It has been found for all except butadiene diepoxide that a given add-on does not result in like fabric properties and that for a certain percentage improvement in dry crease resistance, a higher retention in tensile properties is obtained at the higher AGU: Zn(BF4)2 mole ratio.