Structures of wool fibers 口 Submicrostructure Cotex: each cortex cell composed of ◆ macrofibril microfibrils protofibril keratin polymer molecules(polypeptide)
Structures of wool fibers ❑Submicrostructure – Cotex: each cortex cell composed of macrofibrils – microfibrils • protofibrils - keratin polymer molecules (polypeptide)
Structures of wool fibers kEratin polymer: helix of amino acids Structural characteristics >18 different amino acids each with-N-C-C- backbone a helix: 3 amino acids per turn(right-handed helix) Diversity of amino acids: good for dyeing Polar groups in amino acids: hydrophilicity Cystine amino acid: contains sulfur: degradation by moths and beetles Big side groups and spiral molecular configuration: hard to be packed well leading to low crystallinity(only 25-30%)
Structures of wool fibers ❑Keratin polymer: helix of amino acids – Structural characteristics ➢ 18 different amino acids: each with -N-C-C- backbone ➢ a helix: 3 amino acids per turn (right-handed helix) ➢ Diversity of amino acids: good for dyeing ➢ Polar groups in amino acids: hydrophilicity ➢ Cystine amino acid: contains sulfur: degradation by moths and beetles ➢ Big side groups and spiral molecular configuration: hard to be packed well leading to low crystallinity (only 25-30%)