Immature cotton fibres

Rippon, J. A., Improving the dye coverage of immature cotton fibres by treatment with chitosan. I. Snc. Dvers Colourists. 100 (1984), 298-303. 

Mercerization has been recognised as a method for removing immature (dead) fibres to obtain level dyeing effect on cotton fabrics. The dead fibres are underdeveloped and appear as flat or slightly twisted tapes. They are non-crystalline, convolutions are sometimes absent, cell walls are extremely thin and the lumen is collapsed and hence do not contain dye to same extent as matured fibres. 

In this test a mixture of red and green direct dyes is used to compare the maturity of cotton fibre samples. Immature fibres dye red, and mature fibres green. Mercerization increases the fibre s affinity for green compound and causticization number can be assessed related to the strength of the green hue. Fabric treated with liquid ammonia under industrial mill condition dyes red. 

When a cotton boll opens, the fibres are cut off from the transpiration system of the plant. The fibres then dehydrate and become flattened and twisted. The cross section of the cotton fibre after dehydration is generally kidney-shaped, although the shapes range from near circular in mature fibres to flat in immature fibres. The kidney shape is an inherent phenomenon due to zones of different density in the secondary wall layers. ... 

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