Knowing the total number of fibers examined and the number of mature fibers
the percentage of mature fibers can be calculated as below:
Percentage of Mature fibers = (Number of mature fibers / Total number of
fibers examines) x 100
Maturity Ratio M:
The percentage of the three classes of fibers are combined into a single
index termed the maturity ratio and is approximately proportional to the degree
of cell wall thickening.
i.e. Degree of cell wall thickening ø = 0.577M
Maturity ratio is calculated using the following equation:
M = (N - D) / 200 + 0.7
where N = Percentage of normal fibers
D = Percentage of
immature fibers
The value of N-D is known as immaturity count. From a sample of 100 fibers,
it would be abnormal to find that all the fibers could be classed as normal
fibers. If 100 fibers are examined from the cotton crop grown under the best
conditions, the normal fibers (N) expected would be 67% and the dead fibers (D
or I) to be 7%. Therefore for the chosen standard of N-D of 67 - 7,
Maturity ratio M = (N - D) / 200 + 0.7 = 1
The theoretical value of M will vary from 0.2 for all dead fibers to 1:2 for
all mature fibers.
It can also be calculated from the actual fiber weight per cm H and the
standard fiber weight per cm.Hs by the relation.
M= H/Hs
The standard fiber weight per cm, also called as intrinsic fineness is that
which the fiber would have fully matured in the arbitrary sense of having an N-D
of 60.
Maturity coefficient Mc: (Maturity count)
The fiber maturity count is denoted by the percentages of the mature, half
mature and immature fibers in a sample. It can be calculated using the formula,
Mc = (N + 0.6H + 0.41)/100
where N - percentage of mature fibers.
H - Percentage half
mature fibers
I - Percentage
of immature fibers
For the chosen standard, N = 67% D or I = 7% and H = 26%.
Mc = ( 67 + 0.6(26) +
0.4(7) )/100
Based on the maturity coefficient, the cottons are classed into different
groups as shown below:
Maturity
Coefficient
Rating
Below
0.06
Very immature
0.60 to
0.70
Immature
0.71 to
0.80
Average maturity
0.81 to
0.85
Good maturity
1. Percentage of Mature fibers , N
2. Maturity ratio , M
3. Maturity co-efficient, Mc |
