الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 93 |  |  |
| | | from | 93 | | |
Abstract
The present study was undertaken to investigate effects
and reliability of fiber length distribution on some other
variables and on yam quality and yam appearance.
Materials used in this study comprised seven commercial
varieties. Three of these varieties, belong to the extra-long staple
category, i.e. Giza 45, Giza 70 and Giza 88 and the other four
ones belong to the long staple class, i.e. Giza 86, Giza 89, Giza
80 and Giza 83. Every variety was represented by three lint
cotton grades these were Fully Good (FG), Good (G) and Fully
Good Fair (FGF).
Studied fiber properties included the fiber length
expressed by each of 2.5 % , 50 % span lengths, uniformity ratio
and short fiber content. Fiber strength at (1/8\\ gauge) and
elongation percent measured by Stelometer instroment, fiber
stiffness and toughness were derived.
Micronarie value, Maturity percentage and hair weight
were measured by Fineness & Maturity Tester (FMT). All of
these properties were tested according to ASTM - Designations.
Cotton samples were spun into” 60s” carded yam using a
twist factor ”3.6”; Yam strength was determined by the
Statimate L.L Automatic Tensile Tester and yarn appearance
grades were converted into a numerical index.
Summary ====================
-59-
Data obtained were analysed using statistical Analysis
System (SAS). Simple correlation coefficients, were calculated.
Stepwise regression analysis was applied to study the
relationship between fiber length parameters and other fiber with
yam properties as well as their relative contribution to yarn
strength and yam appearance. The results obtained in this study
could be summarized in the following points:
( I ) -The analysis of variance could be cited in :
1 -Fiber length parameters differed from one variety to another
within the same lint grade and from one grade to another of
the same variety.
2- The extra-long staple varieties were characterized by higher
2.5%, 50% span lengths and lower short fiber content than
long staple varieties. No striking differences in uniformity
ratio were detected.
3- The higher the lint grade the higher were the 2.5%, 50% span
lengths and the uniformity ratio and the lower the short fiber
content.
4- Variation In short fiber content among varieties and also
among grades were more frequently than in other
parameters.
5- Generally, variation of length parameters was resultant from
both variety and lint grade whereas the effect of lint grade
was the preponderant.
Summary ====================
-60-
(II) -Simple correlation coefficients between fiber length
parameters and other variables indicate the
following:
1-The 2.5% span length was found to be closely and positively
associated with fiber strength, stiffness, toughness, yarn
strength and yarn appearance grade, whereas correlations
were strong and negative with short fiber content, fiber
elongation and hair weight.
2 - Positive and highly significant correlations were obtained
between the 50% span length and fiber strength, stiffness
toughness, yarn strength and yarn appearance. Nevertheless,
the correlations with fiber elongation and short fiber content
were strong and negative. Moreover, the 2.5% and 50% span
length did not show obvious relationship with the micronaire
value and the maturity percentage.
3 -The correlations between uniformity ratio and fiber
strength, micronaire value, % maturity, hair weight, yarn
strength and yarn appearance were positively and fairly
strong. On the other hand, there was negative and highly
significant relationship with short fiber content and fiber
elongation, but no consistent relation was found between
uniformity ratio and both of fiber stiffness and toughness.
4 .~ Short fiber content showed negative and significant
correlations with fiber toughness and the mirconaire value,
also correlation coefficients were negative but highly
significant with fiber strength, stiffness, % maturity, yarn
strength and appearance. The relationship was also negative
Summary =====================
-61-
and insignificant with hair weight. On the other hand, fiber
elongation, alone showed positive and high significantly
correlation with short fiber content.
(III)-Stepwise regres ion results indicate the following =
1- For yarn strength, fiber strength ranked first and was followed
in order by 2.5% span length then came micronaire value,
short fiber content, uniformity ratio and maturity percentage.
2- With regard to yam appearance, the most effect was imposed
by short fiber content, the next variable was the 2.5% span
length followed by each of maturity percentage, micronaire
value and uniformity ratio which were of minor contribution.
It could be seen clearly that, all fiber length parameters
except 50% span length, had big share in the variability of
both yarn strength and yarn appearance.
In conclusion, fiber length is a varietal characteristic affected
highly by environmental factors and by conditions imposed by
the lint grade. This character had strong relationship with the
other fiber properties and has high relative contribution to
variability of yarn stren h and yarn appearance as well as many
other yarn properties.