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  • 2.2.1-COTTON VALUE ADDITION-MICRONAIRE

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  • Micronaire

    Chapter 2 - Cotton value addition - The impact of cotton fibre properties on textile 

     
     

    The importance of micronaire, which is determined by genetic (cotton variety) and environmental conditions, was recognized early, and it was also one of the first cotton fibre properties measured by instrument using the airflow principle.

     

    Micronaire is generally used as a measure of maturity, which is true for a specific cotton variety (cultivar) and region. Nevertheless, more generically speaking, it is a function of both maturity and fineness, which affect textile processing and quality independently and differently. It is therefore important, particularly when different cotton varieties and growing regions are involved, to measure maturity and fineness separately, and these will be discussed separately below. Nevertheless, some research has indicated that, for Upland cottons, micronaire is as good as, if not better than, maturity in predicting yarn quality and dyeability. Chellamani et al, for example, found the following relationship between colour difference (ΔE) and difference in micronaire and immature fibre content:

     

    2.2.1-en 

     

    Where micronaire alone is measured, its importance lies in the fact that it affects processing waste (lower micronaire fibres break more easily during mechanical action), neps (lower micronaire fibres are generally more flexible and entangle more easily to form neps), short fibre content, spinning performance, yarn and fabric quality, dyed fabric appearance and neppiness in particular. Lower micronaire cottons also tend to become more easily entangled around particles of trash and leaf, thereby increasing the amount of good fibre removed. These features affect processing performance, and product quality and costs. Lower micronaire cottons also need to be carded slower. Neps can interfere with drafting, resulting in end-breakages during spinning. If micronaire levels within a lay-down or mix vary unduly (by more than 0.2 units), it could lead to streakiness or barré because of differences in dye shade. It is generally considered that both too-low and too-high micronaire cottons should be avoided, the ideal range being between about 3.8 and 4.2 for American Upland type cotton. Nevertheless, micronaire values below 3.8 would be preferable provided the cotton is mature, particularly for rotor spinning.