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! " # $ % … On the outside of the wool ber there is a protecve layer of scales called cucle cells. They overlap like les on a roof. … The scales have a waxy coang chemically bound to the surface. This stops water penetrang the ber but allows absorpon of water vapor. This makes wool water-repellent and resistant to water-based stains. Cuticle & ' [...]...Cortex The cortex – the internal cells - make up 90% of the fibre There are 2 main types of cortical cells – ortho-cortical and paracortical Each has a different chemical composition These two types of cells form in two distinct halves The cells expand differently when they absorb moisture, making the fibre bend - this creates the crimp in wool Nazmul Ehsan, Southeast University 11 Nazmul... Southeast University 16 Matrix The matrix consists of high sulphur proteins This makes wool absorbent because sulphur atoms attract water molecules Wool can absorb up to 30% of its weight in water and can also absorb and retain large amounts of dye This region is also responsible for wool s fire-resistance and antistatic properties Nazmul Ehsan, Southeast University 17 Nazmul Ehsan, Southeast University... strength and flexibility The microfibrils contain pairs of twisted molecular chains Nazmul Ehsan, Southeast University 19 Nazmul Ehsan, Southeast University 20 Twisted molecular chain and helical coil Within the twisted molecular chains are protein chains that are coiled in a helical shape much like a spring The helical coil – the smallest part of the fibre – gives wool its flexibility, elasticity and. .. in wool Nazmul Ehsan, Southeast University 11 Nazmul Ehsan, Southeast University 12 Cortical cell The cortical cells are surrounded and held together by a cell membrane complex The cell membrane complex contains proteins and waxy lipids and runs through the whole fibre The cell membrane complex allows easy uptake of dye molecules Nazmul Ehsan, Southeast University 13 Nazmul Ehsan, Southeast University... like a spring The helical coil – the smallest part of the fibre – gives wool its flexibility, elasticity and resilience, which helps wool fabric keep its shape and remain wrinkle-free in use Nazmul Ehsan, Southeast University 21 Surface characteristic of different fiber Nazmul Ehsan, Southeast University 22 . water penetrang the ber but allows absorpon of water vapor. This makes wool water-repellent and resistant to water-based stains. Cuticle & ' Cortex ()*+,&&apos ;- . (*+/+ ./0 (/.( )//0,1 /+ Cortical. ! " # $ % … On the outside of the wool ber there is a protecve layer of scales called cucle cells. They overlap like les on a. stains. Cuticle & ' Cortex ()*+,&&apos ;- . (*+/+ ./0 (/.( )//0,1 /+ Cortical