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Abstract:
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The formation of an adequate size coating on yarn is
necessary to prevent abrasion and clinging of the yarn during
weaving. Although the size film aids the yarn against
abrasion and clinging, it has a tendency to adversely affect
the yarn elongation, therefore some have assumed a lubricant
is necessary.
Much speculation has occurred about the effects of
lubricant to size film formation on yarns, but few extensive
studies have been performed. Howard Thomas has found that it
is possible to use a derivative tensile test to evaluate the
consistency (fragmentation) of the size film formation on ring
spun yarn, and to relate the results to Sulzer-Ruti Webtester
results. His research indicated that ring spun yarns having
fragmented size film appeared similar to an unsized yarn's
stress-strain curve derivatives. Whereas Thomas' research demonstrated a relationship for
ring spun yarn, it was not known if such a relationship
existed in the other yarn formation systems. This thesis
investigated if such a relationship existed in open-end, air
jet, and textured filament yarns, and if it can be evaluated
by a dynamic tensile test. The investigative results of this
research are as follows:
1. In all yarn types, lubricants were found to
adversely affect the performance of the yarn as
compared to non-lubricated samples. This was based
on the following tests:
" Sulzer Ruti Webtester - Abrasion Resistance
" Tensile and Elongation Analysis - Instron
" Analysis of Force-Load Derivatives - Instron
From the results of this testing it was determined
that an oil based lubricant was more damaging to
staple fiber yarn than a wax lubricant. It was
also shown that an increased concentration of
lubricant increases the severity of the its affect,
based on the levels used in this study. 2. By use of coefficient of fragmentation and
derivative analysis it was determined
that all yarn types exhibit similar size film
degradation and fragmentation results as observed
by Thomasam. This is to say that sized,
lubricated yarns respond more like unsized yarn
than a sized non-lubricated yarn. This result
indicates the lubricant is hampering the proper
size film formation on the yarn structure.
The third specific objective of comparing the effects of
lubricant applied in-bath to lubricant applied after the bath
yielded the following conclusions:
3. For all yarns, the wax and oil in-bath lubrication
was more detrimental to size film than after the
bath lubrication. It was also determined that oil
lubricant was more damaging than wax lubricant when
used as an after lubrication.
Regression analysis was used to determine the
relationship between the Webtester results and the derivative
analysis. Ninety-four percent of the variation to be
explained by utilizing the equation:
Webtester ST-6 = -3121.874 + 10.199(SE strength) +
4.192(Sum of 1st Derivative of Load) [6]
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