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Abstract:
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This thesis research investigated selected fiber
properties and needling parameters to determine their effects
upon fabric strength and water permeability of light weight
geotextiles. Although needlepunched fabrics have been in
existence for over a century, there has been very little
published research in areas of practical manufacturing
conditions for these fabrics.
Geotextiles is probably the largest new market for
industrial textiles in recent history, and needlepunched
fabrics account for a significant share this market. Two
important characteristics that erosion control geotextiles
must have are strength and water permeability. A survey of
previous investigations indicated that some work had been done
which investigated how needling variables and fiber properties
affected fabric strength. other studies investigated the
effects of needling variables and fiber properties on fabric's
water permeability. Because no information was found that
investigated both fabric strength and water permeability in
tandem, research to develop such information was undertaken.
To determine the effects of fiber denier, fiber length,
needlepunch density, and depth of needle penetration on fabric
strength and water permeability, twenty-eight polypropylene
fiber variations were produced with combinations of deniers and lengths. These fibers were then carded into webs which
were cross-lapped, pre-needled and web drafted, then needled
at various levels of needlepunch density and dep~h of needle
penetration. After the needlepunch fabric was produced, it
was run through a convection oven to thermally bond the
fabric. Fabric strength tests were performed on both asneedled
fabric and heat treated fabric, and water permeability
tests were performed on the heat treated fabric. The results
from these tests were statistically analyzed to determine the
effects of processing variables.
The following general results were noted:
Fabric strength - for both as-needled and heat treated
fabric, fabric strength was significantly affected by
fiber length, fiber denier, needlepunch density, and
depth of needle penetration.
1. Increasing fiber length resulted in increased fabric
strength.
2. Increasing fiber denier resulted in increased fabric
strength, up to an optimum point. Beyond that
point, additional increases in fiber denier resulted
in a decrease in fabric strength.
3. Increasing needlepunch density generally resulted in
increased fabric strength.
4. Increasing the depth of needle penetration resulted
in increased fabric strength, up to an optimum
point. Beyond that point, additional increases in
depth of penetration resulted in a decrease in
fabric strength.
Fabric water permeability - For heat treated fabric,
water permeability was significantly affected by fiber
denier, needlepunch density, and depth of needle
penetration. Fiber length was not found to be
significant.
1. Increasing fiber denier resulted in increased fabric
water permeability, but also showed that the degree
of increase is dependent upon depth of needle
penetration.
2. Increasing needlepunch density resulted in decreased
fabric strength, up to a point. Beyond that point
increased needlepunch density resulted in increased
water permeabili ty . This relationship is also
dependent upon depth of needle penetration.
3. Increasing the depth of needle penetration resulted
in decreased fabric water permeability, up to an
optimum point. Beyond that point, additional
increases in depth of penetration resulted in a
increase in fabric water permeability.
Predictive capabilities - Fabric strength and fabric
water permeability can be accurately predicted with
regression analysis equations.
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