Acylation of silk and wool with acid anhydrides and preparation of water-repellent fibers

Silk and wool fibers were acylated with two acid anhydrides, dodecenylsucci nic anhydride (DDSA) and octadecenylsuccinic anhydride (ODSA), at 75 degree sC with IV,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) as the so lvent, the latter of which allowed higher weight gains to be reached. The w eight gain and acyl content of wool was always higher than that of silk. Te nsile properties of silk remained unchanged regardless of weight gain, wher eas wool displayed a noticeably higher extensibility at high weight gain. F ine structural changes of acylated wool were detected by DSC analysis. Mois ture regain and water retention of acylated silk and wool decreased signifi cantly, whereas water repellency increased. SEM analysis showed the presenc e of foreign material firmly adherent to the surface of both silk and wool, whose amount increased with increasing weight gain. These deposits were at tributed to the presence of the modifying agents at the fiber surface on th e basis of the characteristic IR bands. The possible application of silk an d wool fibers acylated with DDSA or ODSA for the preparation of water-repel lent textile materials is discussed. (C) 2001 John Wiley & Sons, Inc.