Thesis Details

Thesis Title: The Effects of Thermal Bonding Methods and Thermal Processing Conditions on the Tensile Properties and Water Permeability of Needlepunched Geotextiles
Thesis Author: Juliane Bodamer
Abstract: 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.