What is the chemical composition of wool?

• Wool is a protein fiber and is thus composed of keratin protein which has 18 different amino acids in its structure. Glutamic acid, serine, cystine, leucine and proline are the major amino acids present in keratin molecules.
• Fibrils are formed when these molecules combine to form long-chain macromolecules which then form fibrillar bundles.
• The protein fibers are composed of peptide chains or amino acids residues joined together by an amide linkage.
• Sulphur linkage, salt linkage, and hydrogen bonds are the three bonds that exist.
• One of the interesting features of wool fiber is that in the relaxed state the polypeptide chain is present in helical form and when the fabric is stretched the chains straightens out which contributes to the springy or bouncy nature of wool imparting it an excellent elasticity.