Importance of Cotton Fibre Maturity

Immature fibres have thinner walls, they are weaker and less stiff than the mature fibres affecting:

1. Spinnability
2. Nep Generation
3. Shade Variation
4. Yarn strength

1. Spinnability

There is an optimum degree of maturity for cotton fibre, above which it tends to be too stiff and bristly for ease of processing and below which it tends to be too flabby and non-resilient. It is not certain just where this optimum lies, though it is probably somewhere between θ=0.8 and θ=0.9. The spinner is much more concerned about the fibres that have little or no wall thickening.

2. Nep Generation

One of the main troubles caused by the presence of these thin-walled immature fibers is nepping. Apart from maturity, causes like small bits or fragments of seed particles attached to the fiber also form neps. Neps are created during processing starting at ginning stage. Further, when rubbing of substances takes place, as in carding, minute knots of tangled fibers are caused and the immature fibers are more prone to this nepping effect. When fine cotton is being processed, the danger of nepping is even more acute, since even the mature fibers are likely to cause neps by faulty processing. In addition, the neps so formed are usually more prominent because of their size relative to the diameter of the yarn.

3. Shade Variation

Immaturity also affects the shade after dyeing. As the response of the primary wall to certain classes of dyestuffs is less intense, the thinner the secondary wall lighter will be shade. Hence fine cotton tends to be lighter in shade than coarse cotton. Apart from this the reflecting surfaces of the fibers of immaturity is with respect to the patches being shown or the weft bars seen in the fabric when yarn made of immature fibers or yarn spun from cotton of different maturity is used as warp and weft. So, summarizing the maturity, the following points are noted. Neps will show up as specks in the dyed cloth.

4. Yarn Strength

Immaturity affects the strength of yarn since the single fibre strength of the cotton fibre is governed by its maturity level. Mature fibres exhibit higher strength than immature fibres.