Preparation Of Metal Ion Modified Melamine Polyphosphate And Its Flame Retardant Properties Of Nylon 66

With the rapid development of automobile manufacturing,electronics,optics and other fields,the performance of PA66 is required to be more stringent.In addition to its good mechanical and processing properties,flame retardant performance is also an important indicator.However,PA66 contains a large number of carbon and hydrogen elements which are easy to burn when heated and accompanied by melt dripping,which limits the wider application of pure PA66.In this paper,melamine polyphosphate(J-MPP)modified by metal ions was prepared by solvent method,and PA66 composites with different flame retardant systems were prepared by adding it to PA66 with basalt fibers(BF)and antioxidants by twin-screw extruder.The flame retardancy and mechanical properties of J-MPP/PA66,BF/PA66 and J-MPP/BF/PA66 composites were studied,and the proportion of J-MPP and BF was determined.The results show that:(1)Melamine,polyphosphoric acid,phosphoric acid,aluminium hydroxide and calcium carbonate were used as raw materials and glacial acetic acid as solvent to prepare metal ion modified melamine polyphosphate.Compared with the infrared spectra of J-MPP and MPP,it was found that metal ions could enhance the hydroxyl activity of polyphosphoric acid;XRD spectra showed that the crystallinity of MPP modified by metal ions decreased;SEM images showed that MPP and Al-MPP were flake crystals,Ca-MPP rod crystals;TGA curves showed that metal ions could enhance the thermal stability of melamine polyphosphate,and the thermal stability was Ca-MPP>Al-MPP>MPP.(2)The mechanical properties of J-MPP/PA66 composite system are lower than those of pure PA66;the mechanical properties of BF/PA66 composite system are greatly improved with the addition of BF;in J-MPP/BF/PA66 composite system,the ratio of Al-MPP to BF is less than 3:2(total addition is 25%)and the ratio of Ca-MPP to BF is less than 4:1(total addition is 25%).(3)The introduction of metal ions improves the flame retardancy of MPP,among which Ca-MPP has better flame retardancy than Al-MPP.The flame retardancy of MPP can reach UL94V-0 level and LOI value is 34.4 at 22%addition.The flame retardancy of basalt fibers to PA66 is not ideal,and "candle-core effect" appears when the addition is less than 10%.When the addition is 25%,LOI value reaches 28.3,UL94 flame retardant level is V-1,and there is no melting.When the total amount of J-MPP and BF is 25%,the ratio of Al-MPP to BF is more than 4:1(total addition is 25%)and the ratio of Ca-MPP to BF is more than 3:2(total addition is 25%).(4)In order to ensure the flame retardant properties of the composites with good mechanical properties,the ratio of Ca-MPP to BF is 3:2?Ca-MPP:BF?4:1(total addition is 25%);for Al-MPP/BF/PA66 composite system,the range is Al-MPP:BF?4:1(total addition is 25%).