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Abstract:
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Fiber producers have recently enjoyed an increasing
trend in the popularity of their viscose rayon products.
In the apparel market, for example, rayon fabrics have made
the move to expensive, high fashion garments. The increase
in rayon popularity has been largely due to development of
the open-end spinning system. Rayon staple is more
expensive than other fibers such as polyester and cotton,
so it is not economically practical to spin 100 percent
rayon yarn on the ring system for most applications.
However, increased package size, increased speeds, and
labor savings make the open-end system an economical way to
process rayon yarn.
The problem today is lack of information. Much work
has been done by the Institute of Textile Technology and
others on polyester and cotton, but limited research has
been published relating viscose rayon fiber properties to
open-end yarn properties. Lack of data is remedied by this
thesis which will help fiber producers and staple yarn
manufacturers to understand the important relationships.
To study the effects of rayon fiber length, denier,
finish type, and finish level on open-end yarn properties,
a classical factorial design was used with two levels of
each fiber property. The levels for each variable were
chosen so that they were wide enough to show significant
effects and interactions yet still within practical
processing limits:
Fiber Length:
Denier:
Finish Level:
Finish Type:
1 1/4 in., 1 1/2 in.
1.1, 1.5
0.2%, 0.4%
regular finish
high cohesion finish
High tenacity, regular viscose staple with the
properties listed above was produced by Courtaulds Fibers
Inc. Sixteen bales of rayon fiber, each representing an
experimental condition, were processed into 30/1 cotton
count yarn. The yarn was produced on an Autocoro open-end
spinning system at two different combinations of rotor
speed and diameter: 65,000 rpm, 40 mm rotor; and 80,000
rpm, 33 mm rotor. Each of the 32 yarn lots was evaluated
in terms of processing performance and final yarn quality.
RotorRing evaluations indicated that the longer fiber
and the finer denier fiber led to higher fiber cohesion,
and the longer fiber exhibited easier opennability. In
addition, the longer fibers and the finer denier fibers
produced yarns of much higher quality than the shorter and
coarser fibers; however, these fibers also resulted in
lower apparent dye uptake as measured by K/S level.
An increase in finish level had a lubricating effect
on the fiber, as it resulted in lower fiber-to-fiber
cohesion. The higher finish level significantly reduced
the number of ends down at spinning. It also resulted in
higher yarn elongation, better evenness, and fewer thin
places in the yarn.
Although the type of finish did not affect as many
yarn properties as the other fiber parameters, the higher
cohesion finish did result in higher single-end strength
and elongation.
Finally, at the higher speed and correspondingly
smaller rotor diameter, ends down rates were significantly
increased and yarn quality deteriorated.
This research has shown that practical changes in
rayon fiber properties can drastically change yarn
processing performance and final yarn qualities. The
results will allow rayon fiber producers in cooperation
with staple yarn manufacturers to engineer rayon fiber for
maximum productivity and the best yarn quality possible.
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