Study On Technique And Product Properties Of Pet Spunbond Needlepunched Geotextiles

PET spunbond needle-punched nonwoven is a significant part of all spunbond production techniques. Spinned filaments, produced by melting the fiber grade PET pellets after drying, are lapped into uniform web, which is directed into bonding area for needle punching. Nonwoven materials with special characteristics are produced after above processing.This kind of nonwoven materials could be named nonwoven geotextiles, clarified according to application fields, having better mechanical and hydraulic properties than traditional needle punched geotextiles with raw materials being staple PET fiber. However, systematic studies about mechanical and hydraulic properties of PET spunbond needle-punched nonwovens has been absent in academic and engineering field home and abroad. Engineering design has been done according to experience obtained from traditional geotextiles application. Studies in this paper will fill the blank that has been existed for years and could provide engineers and manufacturers with scientific foundations about relative properties.As a newly-developed product with only several years of advancement, PET spunbond needle-punched geotextiles has a production technique with specialty. The study has systematically elaborated on the machine characteristics and parameters, including extruders, melts filtration setups, measuring pump setups, quenching unit, air drawing setups and its principles, web formation, needlepunching technique and its characteristics. Technical parameters of key processing parts have been designed in order to systematically study its technical special traits. Key processing parts are quenching unit, web formation setups and needlepunching area.This paper has tested the viscosity of fiber-grade PET pellets for reference to technique design. The study has mainly focused on different mechanical properties of PET spunbond needle-punched geotextiles and staple PET fiber needle-punched geotextiles with different grams per unit. These mechanical properties include tensile strength and elongation rate, tearing strength, CBR burst strength, grab tensile strength. Comparison of above mechanical properties between PET spunbond needle-punched nonwoven geotextiles and staple PET needle-punched geotextiles has been done, where mathematical relations have been concluded, providing scientific guidance for production and engineering design.This paper has studied another essential property of PET spunbond needle-punched nonwovens:hydraulic properties, mainly focusing on its vertical and horizontal permeability. Vertical permeability has been characterized as vertical permeability coefficient, on which the fiber diameter, materials thickness and tested layer number could exert influence; horizontal permeability has been characterized as horizontal permeability coefficient, on which the fiber diameter, and normal pressure could exert influence. In addition, the compression of geotextiles, the relations between normal pressure and materials thickness, has been studied for the sake of horizontal permeability research.