Study On Synergistic Flame Retardant Epoxy Resin With Transition Metal And Borate Polymer

Epoxy resin(EP)has been widely used in various fields such as chemical building materials,interior decoration,electronic packaging,transportation,etc.However,in common with most polymer materials,the flammability of EP greatly limits its application in some fields.The new flame retardant with high efficiency and low toxicity is the development direction of improving the fire safety performance of EP and other polymer materials in recent years.In this paper,two kinds of novel flame retardants were synthesized by using borate ester polymer(BP)as the medium,one is borate ester polymer-iron nanocomposite flame retardant(BP-Fe),the other is ZIF-67 and borate ester polymer as core-shell flame retardant(ZIF-67@BP).The thermal stability,flame retardant properties and mechanical properties of epoxy resin composites modified by these two flame retardants were systematically studied,and the flame retardant mechanism was also discussed.The main research contents are as follows:(1)Based on molecular design,a monomer(HAC)containing phosphorus and nitrogen elements and containing multiple catechiol groups was synthesized.The HAC reacted with multi-functional phenylboric acid monomer(DAB-DOPO),and the nanomicrosphere BP was prepared driven by B-N coordination between polymer chains.Fe3+was introduced into the interior of BP to form BP-Fe nanocomposite flame retardant by the efficient coordination ability of catechol groups and transition metal ions.When BP-Fe was introduced into the EP matrix,the peak heat release rate(PHRR)of the EP/BP-Fe composite was significantly reduced.The PHRR was reduced by 48.2%at the addition of 5 wt%BP-Fe,and the toxic gas emission was also reduced.At the same time,the UL-94 of EP/BP-FE reached V-0 grade,and the oxygen index was also significantly higher than that of pure EP.These results indicate that there is synergistic effect among nitrogen,phosphorus,boron and iron,which effectively improves the flame retardant and smoke suppression properties of EP/BP-Fe epoxy resin composites.(2)A cobalt-based organic frame material ZIF-67 with 2-methyl imidazole as ligand was synthesized by the polymerization of HAC and DAB-DOPO on its surface to get ZIF-67@BP core-shell hybrid flame retardant,which was used as flame retardant for EP.The results showed that ZIF-67@BP increased the carbon residue of EP at high temperature,improved its thermal stability and also greatly improved its the flame retardant properties.The UL-94 grade of the EP/ZIF-67@BP material with 5 wt.%ZIF67@BP reaches the V-0 grade.Compared with pure EP,the PHRR,total heat release(THR),smoke production rate(SPR)and total smoke production(TSP)decreased by 21.9%,3.8%,24%and 21.1%,respectively.The improvement of thermal stability,flame retardant and smoke suppression properties of EP/ZIF-67@BP is mainly attributed to the synergistic flame retardant effect of borate ester polymer and ZIF-67.