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Abstract:
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The geotextile industry has enjoyed tremendous growth from 1 million square yards in
1970 to approximately 325 million square yards in 1992. Nonwovens continue to hold a
sizable lead in the geotextile market over woven and knitted fabrics, and polypropylene is the
most commonly used fiber in this industry.
Nonwoven geotextiles are often manufactured by needlepunching staple fibers together
and then thermally bonding the web. There have been many studies investigating the effects
of needlepunching parameters on fabric properties, and of thermal bonding parameters on
fabric properties. There has not been extensive research on the effects of thermal processing
parameters on the properties of needlepunched polypropylene webs. This study was dedicated
to determining how the selection of thermal bonding method and processing parameters affect
the tensile properties and permeability of needlepunched polypropylene geotextiles.
Thirty-six fabric conditions were produced to investigate the effects of dwell time and
intensity in infrared bonding or dwell time and air temperature in through-air bonding. The
effect of calendering after the first infrared or through-air bonding was also investigated.
Strength-to-weight ratio, elongation, tear strength, puncture resistance, and water permeability
were analyzed for all conditions. Thermal analysis and melt flow analysis were conducted for
selected conditions.
Results indicated that through-air bonding improved the machine direction strength-toweight
ratio of fabrics treated at the high temperature levels and dwell times within the range
studied. Long exposure to high intensity infrared radiation negatively impacted the fabric tensile properties. Calendering, long exposure to high intensity radiation, and high air
temperatures reduced water permeability.
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