The action of epichlorohydrin in the presence of alkalies and various salts on the crease recovery of cotton

Abstract

AbstractAs a phase of an investigation of the cellulose–epoxide reactions, experiments have been performed in which epichlorohydrin reacted with cotton cellulose in the presence of sodium hydroxide and various salts. Acidic and basic salts, as well as those which are relatively neutral in aqueous solutions, were used in pretreatments for the cellulose–epichlorohydrin reaction. No reaction with cellulose occurred in the presence of acid salts and only very slow addition of epichlorohydrin to cellulose in the presence of neutral salts; the greatest reaction was produced with basic salts. Particular emphasis was given to use of certain salts known to cause epichlorohydrin to undergo a type of cyclization reaction. Previously published methods, used for imparting both wet and dry crease resistance to cotton fabrics by means of diepoxides in the presence of NaOH, have resulted in wet crease resistance only when applied to the application of epichlorohydrin. Among the basic salts investigated, 20% solutions of sodium azide used in pretreatments were found to produce low weight gains of epichlorohydrin and a fair degree of dry and wet crease resistance in cotton after a slow reaction at 25°C. or a faster reaction at 80°C. The greatest improvement in dry crease resistance with epichlorohydrin was obtained by pretreatments with concentrated solutions of sodium orthosilicate, sodium metasilicate, or trisodium phosphate at 80°C. The effects of amount of water at time of reaction as well as speeds of reaction with the various pretreatments have been considered. Optical and electron microscopical examinations of fibers and ultrathin cross sections of fibers, respectively, after immersion in cupriethylene diamine (cuene) have indicated that the cellulose–epichlorohydrin reaction at 80°C. after pretreatment with concentrated solutions of silicates or phosphates differed from that after pretreatment with sodium hydroxide at all concentrations. Even when the pretreatments were with dilute sodium hydroxide, the epichlorohydrin‐reacted fibers were more swollen in cuene than were those treated fibers which had been pretreated with the concentrated silicates or trisodium phosphate solutions. Decrease in amount of swelling and dissolution in cuene was found to correlate with increase in dry crease resistance of the fabrics. While all these treated fabrics possessed high wet crease resistance, only those pretreated with the aforementioned concentrated salt solutions possessed good dry crease resistance. Effects of base‐catalyzed addition of certain monoepoxides to cotton on the resultant crease resistance properties of the fabrics have been reported and compared with properties imparted by epichlorohydrin. Attempts have been made to explain why the number of cellulose crosslinks formed per unit of time by epichlorohydrin is greater, when silicates or phosphates at high concentrations are present with hydroxyl ions, than when hydroxyl ions only are present.