Preparation and performance of halogen-free flame retardant modified ultra-high molecular weight polyethylene fiber
By nitrogen and phosphorus flame retardant compounding,with melamine cyanurate(MCA)as the main flame retardant,aluminum diethylphosphonate(ADP)as the co-efficient flame retardant,hexagonal boron nitride(h-BN)as the heteroge-neous modifier,and white oil as the solvent,halogen-free flame retardant ultra-high molecular weight polyethylene(PE-UHMW)fiber were prepared.Firstly,the flame retardant powder was dried and surface treated,then it was co-mingled with white oil,and after ultrasonic liquid-phase dispersion and high-speed grinding by mill,the halogen-free flame retardant slurry was obtained.The flame retardant slurry was dispersed into the PE-UHMW spinning stock,and extruded by the twin-screw extruder to obtain the lyophilized filament,which was solvent-extracted,dried,and thermally drafted to obtain the flame retardant PE-UHMW fibers,and then the flame retardant properties as well as the mechanical properties of the fibers were characterized.The results show that the powder particle size can be reduced to hundred nanometer level by repeated grinding of the mill,which is easier to be dispersed in the PE-UHMW dissolution solution and greatly improves the spinnability of the flame retardant fibers;the heterogeneous modifier improves the flame retardancy of the compound flame retardant and the flame retardant grade of the material.When the addition amount h-BN is 4%,the mass fraction of flame retardants can be added to 20%,the fiber limiting oxygen index value reaches 27.5%,and the material flame retardant grade can reach V-0.Above all,through a series of modification means,it can make PE-UHMW fiber maintain good spinnability after adding a large amount of flame retardant powder.Meanwhile,the modification has less effect on the mechanical properties of the fiber,which broadens the application field of PE-UHMW fiber and enhances its use value.
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