Thesis Details


Thesis Title: The effects of fiber length, fiber denier, needlepunch density, and needle penetration on the physical characteristics of as-needled and heat treated
Thesis Author: Kirk Smith
Abstract: 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.