The Maturity Of Cotton Fibre

The maturity of ratio concerns the development of the cell wall.The perimeter of the cotton fibre is least affected by environment and most by heredity,but cell wall thickening is highly sensitive to growing condition.Even when cotton is grown under favorable condition a small proportion of the fibre will be under development or immature,but adverse weather,poor soil,plant disease,and pests,will increase the proportion of immature fibre and lead to trouble in processing.Immaturity in tje truft tends to remain the patches and immature fibre tends to associate even through to the yarn stage.Small patches or crops can be affected and the Chances of maturity variation are great in any symbol or bale of cotton.

One of the main trouble caused by the presence of these thin walled immature fibres is nepping.Apart from natural cause like fragments of seed pod attached to a fibre,nepping is CREATED during processing,starting at the gin.Where rubbing between surfaces occurs, that is during carding,minute knots of tangled fibre are caused and flabby immature fibre are most prone to this nepping effect.When fine cotton are being processed the danger of nepping is even more acute,since even mature fine cottons can be nepped by faulty processing.I addition,the neps so formed are uaually more prominent because of their size relative to the diameter of the finer yarn.

Immaturity also affect the shade after dyeing.As the response of the primary wall to certain classes of dyes is less intense,thinner the secondary wall the lighter the shade.Fine cotton tends to be lighter in shade than coarse cotton.This is only a partial explanation of shade difference.The color component reaching the eye from dyed fibre is mainly composed of rays of light reflected from internal surface.If the walls are thinner there will be greater possible number reflecting surfaces per unit mass of cellulose and,consequently,a greater amount of light emerging after passing through only a small amount of stained material.The appartment shade is there for lighter.
With two deliveries of weft spun from cotton different maturity,weft bars are possibility.Neps will show uo as speaks inthe dyed cloth.

In order to assess the quality of cotton with respect to maturity and its effect on ends down,yarn strength,dyeing trouble,and so on,some method of measurement is required.The degree of cell wall thickening may be expressed as the ratio of the accrual cross-sectional area of the wall to the area of the circle with the same perimeter.

Direct measurement of this ratio is not a practicable routine test and is not normally done.An indirect method which has been in use for a number of years is the cotton fibre immaturity count.A convenient time at which to make this test is after a sorter diagram has been prepared for the measurement of the fibre length characteristics and fibre weight per centimeter.After the fibre weight has been determined,five tufts of cotton are left on the velentpad. Each tuft is laid on a microscope slide.the fibres parallel but separated,and a cover slip put over the middle.
The fibre are then irrigated with a small amount of 18 per cent caustic soda solution which has the effect of swelling them.The presence or absence convolution is then observed,preferably by means of a projection microscope.This enables the fibre to be classified into three groups.
1.Normal Fibres.
2.Thin-walled Fibres.
3.Dead Fibres.
Mature fibres with a well-developed cell wall and pronounced convolution in the raw state become eode like after swelling.These rod-like fibres are closed as 'Normall' Dead fibre appear ribbonlike even after swelling.Thin walled fibres are those lying between the other two classes.Borderline cases may be judged from the thickness of the cell wall relative to the total width of the 'ribbon'.

The Counting And Classification Is Done In Three Stages:

1.All the fibre are counted.
2.The rod-like fibre are counted.N
3.The dead fibre are counted.D
Classification and counting is carried out for each the fibre groups,the number converted to percentage,and the means calculated.The result of the test is then expressed as N-D,that is 64-14 would mean that 64 per cent of the fibres counted were classed as normal and 14 per cent classed as dead;therefore,by subtraction,22 per cent would be classed as thin-wall fibres.
It is a desirable to express the result as a single figure which would give the actual maturity observed as a fraction of some suitably chosen standard maturity.From a sample of 100 fibres it would be ABNORMAL to find that all the fibres could be classed as 'normal' fibres. A standard was chosen which was of fully matured cotton crops grown under the best possible conditions.The standard chosen was:
N-D=67-7=60
It is also desirable that the result should be propotional to the geometrical measure of cell wall thickening,the 'degree of thickening'.

Maturity Ratio:

The maturity ratio to be derived from these conclusions is the ratio which express the actual fibre weight per centimeter, H,in relation to a standard fibre weight per centimeter Hs.

By definition,the standard fibre weight per centimeter,Hs, is that which the fibre would have if it were fully matured in the arbitary sense of having an
N-D.

The link between immaturity count and fibre weight:

Peirce and lord found N-D and H for several pure strains of cotton and within each series only the maturity varied.A linear relationship was found betwee H and N-D: