Page 269 - Handbook of Properties of Textile and Technical Fibres

Tensile properties of cotton fibers: importance, research, and limitations 243

when the ribbon width of fiber measured by the Mantis was added to the Mantis
single-fiber strength. The empirical equation developed in this study was as
follows:

Mantis breaking load
TenacityðHVIÞ¼ 12:32 þ 530:49 2
Ribbon width
Although this relationship was associated with higher scatter, leaving about 30% of
the effect unexplained, it provides a fair exploratory guideline, particularly in light of
the point that because the bundle tenacity was expressed in cN/tex, the Mantis breaking
load was normalized with respect to the square of the ribbon width in microns.
In another study by Cui Xiaoliang et al. (2003), the authors went against the common
wisdom of treating single-fiber strength as an independent variable in the bundle
strength/single-strength relationships and attempted to predict or estimate the single-
fiber strength from the bundle strength. They alluded to the hindering effect of cotton
fiber crimp in the bundle and pointed out that despite the combing and brushing of
the HVI fiber beard, the crimp is sustained in the prepared samples and to completely
remove it, more harsh combing and brushing will be required, which can cause fiber
damage. Therefore, the estimation method for straight fiber bundles cannot be used
effectively for slack bundles (or bundle composed of fibers with unequal lengths
between the jaws of a tensile tester due to fiber crimp variation). The authors used an
earlier model developed by Cui Xiaoliang et al. (1999) and attempted to verify the
validity of the model using tests of five samples of different American Upland cottons.
Single-fiber tensile testing was made using the Mantis instrument, and the bundle
strength was tested using HVI-Motion Control Fiber Information System 4000. The
estimated single strength values were very different from the Mantis single strength
values, and in one cotton sample, there was up to 8.5 cN/tex difference.

7.11.4 Empirical relationships between HVI bundle strength and
Favimat single-fiber strength
In a Master’s degree study by Hosseinali (2012), one hundred and four reference
cottons, mostly consisting of Upland varieties of highly diverse values of fiber
properties, were tested for bundle strength using HVI and for single-fiber strength
using the Favimat instrument. This study yielded the following simple regression
equation relating bundle strength and single-fiber strength:

HVI Bundle Strengthðgrams per texÞ¼ 6:3542 þ 1:0214 Favimat Single

Fiber TenacityðcN per texÞ

The correlation coefficient of this relationship was surprisingly very high at a value
of 0.909. However, HVI testing was not made of cotton fibers obtained from the bales;
it was rather collected from card webs after a great deal of combing and brushing
applications.