الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The present investigation was conducted for the following aims: (i) to drive
equations for predicting the physical properties of cotton yarn from the physical
properties of the cotton fibers from which this yarn was spun, in view to help
cotton breeder, trader and spinner, (ii) to find out the effect of some processing
variables, namely, yarn count, twist multiplier, carding and combining as well as
cotton variety and their interactions on the physical properties of the cotton spun
yarns, (iii) to compare the new and relatively older varieties with respect to quality
and spinning performance, and (iv) to propose the best end uses for raw cotton
fibers and cotton spun yams dealt with in this investigation.
The raw cottons used were the relatively older Giza 75 and new established
Giza 83 and Giza 85 long-stapled varieties (LS), as well as the relatively older Giza
70 and Giza 77 and the new introduced Giza 84 extra long-stapled cotton varieties
(ELS). Twenty kg bulk sample from each of Giza 83, Giza 84 and Giza 85 new
introduced varieties were provided by the Cotton Maintenance Research
department, meanwhile 20 kg bulk sample from each of the relatively older Giza
70, Giza 75 and Giza 77 were provided by the Cotton Breeding Research
Department, CR!, ARC, Giza. Fiber and yam tests as well as spinning were
conducted at controlled atmospheric conditions of temperature (20°C±2) and
relative humidity (65%±2). The results of fiber and yam physical properties were
subjected to statistical analysis techniques for simple correlation coefficients,
forward selection statistical procedure for dependent variable according to SAS
(1988). The results for the effect of the processing variables were analyzed for
variance. The comparison between new and old varieties were treated through
variation parameters, comparison with the world yam levels as well as percentage
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increase and decrease of the new varieties with respect to the relatively older
varieties. The most important results achieved could be summarized as follows:
1. Contribution of fiber to yarn physical properties
1.1. The longer, the more uniform the fiber length distribution, the higher the
fineness/maturity of the fibers, the stronger and the more extensible the
bundles of the fibers. However, the bundle stiffness and toughness did
not show de t;inite trend with either length or fineness/maturity
measurements which is difficult to be interpreted physically.
Nevertheless, the relationships differ from LS to ELS and to LS+ELS
categories.
1.2. The more even the less imperfected, the less variable in strength and
extension, the stronger, the more extensible and toughier the carded
yams spun from LS, ELS, LS+ELS varieties and the combed yarns spun
from ELS varieties. However, the stiffness behaved differently from LS
to ELS to LS+ELS carded to ELS combed yarns.
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1.3. Based on the values of’r’s between various yarn properties, it was seen
that the best three physical properties of spun yarn to be predicted from
the’ fiber physical properties were; yam strength, evenness and nep
countl100 meters.
1.4. The best equation for predicting the strength of 405 and 60s carded LS
yarns from group 1 and group 2 of fiber properties were equations No.
7, 14, 20 and 29, respectively. Meanwhile, the best equations for
predicting strength of 60s and 100s ELS carded yams from group 1 and
group 2 of fiber properties were equations No. 32, 45, 52 and 62,
respectively. The fiber properties required to predict yam strength differ
from one count to another and from one length category to another.
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S S . 1.5. The evenness of LS 40 and 60’ carded yams were best predicted from
group I and group 2 fiber properties by equation No. 69, 74, 81 and 92,
respectively. Meanwhile the evenness ofELS 60S and 100s carded yams
were best predicted from group 1 and group 2 of fiber properties by
equations No. 99, 106, 112 and 117, respectively. However, the fiber
properties needed for predicting yam evenness differ from one count to
another and from LS to ELS in case of any group of fiber properties.
1.6. The nep count/IOO meters in LS 405 and 60S carded yams could be
safely predicted from group 1 and group 2 of fiber properties by
equations No. 125, 131, 139 and 145, respectively. whereas the nep
count of ELS 60S and 100s carded yarns were best predicted from group
1 and group 2 of fiber properties by equations No. 151,157,167 and
176, respectively. Similarly, the fiber variables included in the prediction
equations in case of group 1 and group 2 of fiber properties differ from
one count to another and from LS to ELS categories.
2. The effect of variety and processing variables on the physical
properties of cotton yarns.
2.t. For LS category, Giza 75 produced the strongest, the more uniform in
strength, stiffer and more even and the lowest in thick places, followed
by Giza 85 and Giza 83 yarns. The varieties ofELS category take the
above descending order as Giza 84, Giza 70 and Giza 77.
2.2. The strength, elongation % and evenness decreased with increasing the
fineness of the yam. Nevertheless, the strength and elongation %
variations as well a the number of imperfections increase with increasing
the yarn fineness.
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2.3. The trend of twist with strength, strength and elongation %variations
and imperfections differ from LS to ELS carded or combed yams,
possibly due to the differences in optimum twist from one category to
another and from carded to combed yarns.
2.4. The variety x count interaction exerted significant effect on all tensile
properties except the strength and elongation of LS and ELS carded
yams and the stiffness of ELS combed yams. However, the trend I
differed from one variety to another. On the other hand, the unevenness
and imperfections increased with increasing the count of LS and ELS
carded and combed yams.
2.5. The variety x twist multiplier interaction exerted significant effects on
strength, strength variation and toughness ofLS carded yams. Giza 8S
showed the best response to twist and was toughter and more even than
Giza 75 and Giza 83, possibly due to the differences between these
varieties in optimum twist multiplier. For ELS carded yams, the trend
differed from one yam property to another. For ELS combed yams, the
effect was only significant on the strength variation.
2.6. The count x twist multiplier interaction exerted significant effects on
strength and elongation variations and evenness of ELS carded yams
and on the imperfections ofLS and ELS carded and combed yarns.
1.7. The second order variety x count x twist multiplier interaction exerted
significant effects on strength and elongation variations as well as thick
places and neps ofELS yarns. However, the effect was only significant
on the imperfections and evenness of LS yarns.
3. Comparison between new introduced and older commercial varieties
both Giza 70 and Giza 77. Nevertheless, Giza 84 was stronger and more
extensible than Giza 77 and lower in stiffness higher in toughness than
Giza 70 and Giza 77.
3.4. Similar to the trend of the physical fiber properties, Giza 75 carded yams
showed superiority of yam physical properties over those of Giza 85
yams which was better than Giza 83 yams.
3.5. Giza 84 carded yams, in most cases were superior in tensile properties,
evenness and less inperfected than both Giza 70 and Giza 77 yarns,
possibly due to the superiority of most fiber physical properties with the
exception of fiber length.
3.6. Giza 84 combed yams were superior in all yarn physical properties than
those of both Giza 70 and Giza 77 combed yams, which is likely due to
the superiority of fiber properties of Giza 84 over those of Giza 70 and
Giza 77 varieties.
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3.7. In conclusion, the attention of cotton breeder and technologist must be
attracted to more emphasis in breeding within the LS category.
However, their role within ELS category is highly appreciated .
4. Proposed end uses for raw cottons and cotton spun yams
Various end uses were proposed for the different raw cottons and spun yarns
dealt with in the present investigation based on their physical properties as well as
the recent technologies, presently applied.