Light Microscopy of Polymer-Treated Wool

Abstract

l'hotomicrographs are shown which confirm previous deductions that the effective ness of polymer treatments in reducing felting shrinkage of wool is rdated to the spreading of polymer over the surface of fibers. Chemical pretreatments which increase the critical surface tension of wool allow better spreading so that polymers are then deposited as thin surface films instead of in relatively large lumps as on normal wool. Only small amounts (1-2%; on the weight of wool) of polymer are therefore required when conditions for good spreading of polymer on wool are realized. Shrinkage-time curves of polymer-treated wool have the same shape as those of untreated wool and of wool made shrink-resistant by oxidative treatments. Polymer is not removed during the shrinkage tests. so that the actual mechanism of felting is probably the same in all cases.

Dyeing of Resin-Treated Wool

“…Upon dyeing with the acid dye Alizarine Fast Blue CL (C. I., 62055), it was noted that fibers cross-linked with either formaldehyde or dimethylol ethylene urea (DMEU) dyed more completely and more rapidly than untreated wool. These observations were surprising in view of the literature reports which would suggest that the treated wools should dye more poorly [3,4,8]. Accordingly, samples of a wool fabric were given a number of treatments (Table I) A scoured, undyed plain-weave woolen fabric (6.2 oz/yd2, 27 warp ends and 24 filling picks per inch, 97 tex yarns) made up of a mixture of a blend of Texas 64's and Australian 62's, , 2-in.…”

“…Dyeing or staining of fibers, often coupled with microscopic examination of cross sections, has frequently been employed as a means of determining the locus of resins or other additives deposited in or on the fiber [2][3][4][5][6][7][8][9] . Often, a particular dye was selected and, on the basis of rate of color absorption by the fibers and cross-sectional examination, a conclusion was reached as to whether the resin was deposited within the fiber or more nearly on the fiber surface.…”

“…These same authors postulated that the cystine content in hydrolyzates of oxidized wool represents not only cystine which existed as cystyl residues in the fibers, but also cystine formed from disproportionation of partially oxidized cystine residues (Table I) during hydrolysis. Maclaren, Leach, and Swan [ 4 ] , by examination of wool oxidized in dilute peracetic acid, have shown that the cystine content, determined by hydrolytic methods, is higher than that indicated by the nonhydrolytic cystine determination of Leach [ 3 ] . Maclaren, Savige, and Sweetman {5] ] demonstrated that cystine monoxide II and dioxide III…”

Improvement of Luster of Wool Fabrics

“…It may then be repr ented by the equation z = f (x, y). Those properties f the surface which are independent of the particular 0 ientation of the axes x and 9 can be expressed in terms of certain moments or invariants of the surface, according to the methods of statistical geometry which we e developed for other fields of interest, e.g., by Lo guetHiggins [6].…”

“…The , residues on the fibers show these clamshell or unduloid shapes under the microscope. However, pictures have been published of acrylic polymer tubes removed from wool fibers [6] and of polyamide deposited by interfacial polymerization [20]. Evidently, it should be possible to deposit polymer as a film.…”