Internal lipid content and viscoelastic behavior of wool fibers



Wool is a natural keratin fiber made up of cuticle and cortical cells held together by the cell membrane complex (CMC), which contains few internal lipids (IWLs) (1.5% by mass). IWL arouse considerable cosmetic and dermatological interest because of its high proportion of ceramides. In this work, IWLs were extracted with acetone, methanol, and dichloromethane/acetone solvents, and the possible alteration of the extracted fibers with respect to their textile feasibility was analyzed. Parameters of yield, fibril, and matrix viscoelastic behavior, deformation work, and breaking elongation were useful in highlighting the effect of internal wool lipids on the mechanical properties of the fibers. The extraction with acetone and methanol solvents supplied good yields of IWL. Although extraction with methanol achieved the richest extracts, the fibers were chemically modified. By contrast, although acetone-extracted fibers had similar properties after treatment, alkaline solubility was lower and fiber length and barb were superior. In the mechanical analysis, a prior extraction of IWL increased yield tenacity and decreased the elongation at break of the fibers, maintaining the feasibility of extracted wool for textile purposes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3252–3259, 2004