| At present,there are two kinds of spunbonded needle-punched geotextiles:polyester spunbonded needle-punched geotextile and polypropylene spunbonded needle-punched geotextile.However,due to technology and other reasons,the only spunbonded needle-punched geotextile produced by China is polyester spunbonded needle-punched geotextile.Although Polyester spunbonded needle-punched geotextile has the advantages of high mechanical strength,UV resistance and good aging resistance,it has the disadvantage of poor alkali resistance.With the increasingly serious geological pollution in China,the requirement on acid and alkaline resistance of geotextile has become higher.Polyester spunbonded needle-punched geotextiles not only have high strength,good wear resistance,low temperature resistance,etc.Most importantly,they have excellent acid and alkali resistance,so they play an irreplaceable key role in underground acid and alkali environment and harsh environment.Therefore,a new method for producing long wire geotextiles is proposed in this paper.The method is different from the traditional spunbonded needle-punched for the preparation of geotextiles.Directly selecting high strength polypropylene filament as raw material,using air as a filament power forward pulling force to unwinding filament,separating the filament fiber by the using the combination of electrostatic wire separation and mechanical wire separation,then piling it into a net,then it is reinforced by needling,and then the geotextile is prepared by cutting edge and winding.It is obvious that the key of this method is the separation of silk,the quality of the product is directly affected by the effect of filament separation.In this paper,three methods for the characterization of filament fiber distribution are proposed,which are the contrast of multiple images,the ratio of filaments and the histogram of the gray.The influence of filament fiber specification,the wind pressure,the voltage,the angle of the slitter and the frequency of the swaying plate on separating filaments are explored.The results show that,to a certain extent,the larger the filament stiffness is,the greater the wind pressure is,the greater the voltage is,the larger the angle of the wire board is,and the larger the frequency of the wire board is,the better the distribution of silk is.The filament fiber net was prepared by using the best technological parameters of filament separation,Polypropylene filament geotextiles were prepared by reinforcing the fiber net with different needling density.The effects of the needle density on the properties of the polypropylene filament geotextiles were tested and analyzed.The results showed that the larger the surface density and the greater the needle density is,the bigger the longitudinal and transverse tensile strength is,the bigger the vertical and horizontal tear strength and the bursting strength is,the worse the vertical permeability and the smaller the effective pore size.The transverse tensile strength and tear strength of the products are all greater than that in the longitudinal direction.When the surface density is certain,the comprehensive properties of the polypropylene long wire geotextiles prepared by the needle density of 400 prickly/cm2 are the best.When density is 600g/m2,the performance is as follows:the thickness of 4.248mm,the tensile strength is 38.98 kN/m,the transverse tensile strength 49.02kN/m,longitudinal elongation is 48.3%transverse elongation is 32.7%longitudinal tear strength of 886N,1466N transverse tear strength,bursting strength is 8914N,the vertical permeability coefficient is 2.5mm/s,the effective aperture is 0.08mm.The performances index of polypropylene filament geotextile prepared in this paper can meet the requirements of national standards,and the performances are beyond the polyester spunbonded needle-punched geotextile produced by a well-known company. |
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