Study Of Nanosized Flame Retardants:Modifications And Application In EPDM Composites

This paper mainly focus on the modification of nano-scale flame retardant and its influence on the structure and properties of EPDM.The main content of the paper has the following three parts:1.EPDM/MH composite materials were prepared by using micro-MH and nano-MH as flame retardants respectively.The results of mechanical properties show that,compared with micro-MH,nano-MH composite material less loss of mechanical properties.nano-MH was coated by Oleic acid(MH-OA),and than prepared EPDM composites.LOI and mechanical properties test show that the oleic acid modified magnesium hydroxide has little effect on the limiting oxygen index of the composites,but can significantly improve the compatibility with EPDM at the lower dosage,The mechanical properties of the material are significantly improved.2.The eucalyptol and APTES modified cyclophosphazene derivatives(EuHCTP,mHCTP)were synthesized respectively.The composition and structure of the synthesized cyclophosphazene derivatives were analyzed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy.The oxygen index tester,thermogravimetric analyzer and universal material testing machine were used to investigate the influence of EuHCTP on the flame retardancy and mechanical properties of EPDM/MH composites,and the effect of EuHCTP on irradiation efficiency was studied by gel content test.The results show that EuHCTP can improve the thermal stability,flame retardancy and toughness of the composites.When 6%EuHCTP was added,the limiting oxygen index(LOI)of the composites reached 29.5,reached the flame retardant level,the elongation at break increased to 713%,while the tensile strength of the composites decreased.After irradiation crosslink,tensile strength did improve,but with the increase of the amount of EuHCTP,the degree of crosslinking of the material decreased,resulting in weakened mechanical properties,EuHCTP reduced radiation crosslinking efficiency.mHCTP as a silane coupling agent can improve the dispersion of MH,flame retardant properties also improved;when used as a synergist,mHCTP and MH did not co-flame retardant effect,the mechanical strength of the material also decreased,but the toughness improved.3.Polydopamine-coated multi-walled carbon nanotubes(PDA-MWCNTs)were prepared,the effects on the properties of the composites were investigated by transmission electron microscopy,scanning electron microscopy,micro calorimetry(MCC)and mechanical properties testing.The experimental results showed that dopamine was successfully coated on the surface of multi-walled carbon nanotubes.The addition of PDA-MWCNTs improved the flame retardancy of the composites and was well dispersed in the polymer.After the addition of PDA-MWCNTs,almost no black smoke.With the increase in the amount of added,smoke suppression effect is more obvious.Compared with the pure MWCNTs,the PDA-MWCNTs further reduced the heat release of the composites at a low dosage,When the amount of PDA-MWCNTs added is 0.5%,the peak heat release rate of the composite is 286.6 W/g,which is 70%lower than that of pure EPDM,the synergistic flame retardant effect between PDA and MWCNTs was achieved.