The Research On Preparation And Performance Of Flame Retardant PA6

In this paper,using modified nylon 6（PA6/PEPA）as raw materials and phosphorus-nitrogen flame retardant ammonium polyphosphate（APP）,organic hypophosphite-diethyl zinc hypophosphite（ZDP）and transition metal oxides-molybdenum trioxide（Mo O₃）as flame retardant additives to prepare PA6/PEPA/APP,PA6/PEPA/ZDP,PA6/PEPA/Mo O₃ blends respectively by a twin-screw extruder.The structure and properties were characterized by means of scanning electron microscopy（SEM）,Fourier transformed infrared spectrometry（IR）,differential scanning calorimetry（DSC）,thermogravimetric analysis（TGA）,the tensile testing machine,limiting oxygen index（LOI）,vertical burning test（UL-94）and cone calorimeter（CONE）.The results showed that when the content of APP was more than 10wt%,the LOI of blends increased to 24-25%;When the addition amount was 25wt%,the heat release rate peak and total heat release decreased by 20.2%and 44.3%respectively,the maximum rate of mass loss decreased by 44.1%and carbon residue quality increased from 2.7%to 17.6%.The flame retardancy of PA6 was improved.But,the dispersibility of APP in blends was poor,which reduced the tensile properties.The compatibility of ZDP in blends was so good that it is evenly dispersed.While the LOI of the blends were increased to 26%when the content of ZDP was more than 5wt%.When the dosage of ZDP was increased to 25wt%,the thermal stability of the blends was improved,the heat release rate peak and total heat release amount decreased 31.8%and 9.5%respectively,the maximum rate of mass loss decreased by 38.2%,the residual carbon mass increased by 2.2 times,and the formation of dense carbon layer improved the flame retardant properties of PA6.The dispersion of Mo O₃ in blends is relatively good.Mo O₃ played a synergistic role in flame retardant with PEPA.When the dosage was 0.75wt%,T_max increased by13℃,the maximum rate of weight loss decreased by 34.8%,and the carbon content at 700℃increased by 25.9%.When the dosage was 1.0wt%,the LOI value of the blends increased to 27%,and the PHRR,THR and PMLR decreased.Compared with pure PA6,PA6/PEPA/APP system has relatively good charcoal performance.PA6/PEPA/ZDP system has better mechanical properties as well as flame retardancy.PA6/PEPA/Mo O₃ system with a little amount of flame retardant can achieve better flame retardancy.