Preparation And Flame Retardant Performance Of Epoxy Resin/Layered Metal Phenylphosphonate Composite

Epoxy resin(EP),as one of the typical thermosetting materials,has good mechanical properties,solvent resistance,excellent electrical insulation,and flexible manufacturability.It is widely used in machinery,electrical,aircraft ferry and other fields.But epoxy resin is very easy to be ignited,which greatly limits its application range.Combining the research status of phosphorus,metal element flame retardants and polymer/layered compound nanocomposites at home and abroad,as well as the research work of this research group,it is believed that the combination of the layer barrier effect of the layered compound and the catalytic carbonization effect of the metal phosphate is likely to become a new and efficient flame-retardant technology for flame-retardant polymer materials.Based on this,this article designed and synthesized layered tin phenyl phosphonate(Sn PP),modified it with bio-based flame retardant ?-cyclodextrin(?-CD),and studied the flame retardant properties of composite materials.In order to further improve the flame retardancy,designed and synthesized of manganese phenyl phosphate(Mn PP)and iron phenyl phosphate(Fe PP),and different modified flame retardant were used to modify them.The above-mentioned layered metal phenyl phosphates had been studied on the flame retardancy,thermal stability,smoke suppression and toxic and harmful gas release properties of EP composite materials,and the flame retardant mechanism was explored.Therefore,the following research work has been done using phenylphosphonate as the flame retardant in this paper:In this paper,layered tin phenyl phosphate(Sn PP)was synthesized by hydrothermal method,and the green and environmentally friendly bio-based flame retardant?-cyclodextrin(?-CD)was used to modify Sn PP to obtain ?-CD@Sn PP and added to EP to prepare EP/?-CD@Sn PP nanocomposites.The results showed that with the increase of flame retardant content,the thermal stability of the composite material increases successively.The maximum carbon residual content reaches 27.8 wt%.The EP/6?-CD@Sn PP nanocomposite's vertical burning test(UL-94)can pass the V-1 rating and the limiting oxygen index(LOI)value increased to 31.2 %.This is because?-CD@Sn PP releases a large amount of water vapor during the combustion process,phosphorus-containing compounds and Sn oxides.It can catalyze the EP composite material to form a rich carbonaceous char layer,block the heat and mass transfer between the matrix and the outside,and reduce the risk of fire.In order to further improve the flame retardancy of EP,a new layered flame retardant manganese phenyl phosphate(Mn PP)was designed and synthesized and modified with triphenyl phosphine oxide(TPPO).The TPPO-Mn PP hybrid flame retardant was obtained and added to the EP matrix to form EP/TPPO-Mn PP nanocomposites.The results demonstrated that TPPO-Mn PP can significantly increase the residual char yield of EP polymer.The char yield of EP/4TPPO-Mn PP nanocomposite was 22.4 wt% and the thermal stability was significantly improved.It had passed UL-94 V-1 rating and the LOI value was 29.5 %.The addition of TPPO-Mn PP also significantly reduced the heat release rate(HRR),the total heat release rate(THR),smoke production rate(SPR)and total smoke production(TSP)of polymer materials.The TPPO-Mn PP layer has a barrier effect during combustion,extending the heat and the escape path of toxic and harmful gases.Therefore,the smoke suppression performance of the composite material and the performance of suppressing the release of toxic and harmful gases are effectively improved,thereby improving the fire safety.In order to further improve the flame retardancy of EP,layered iron phenyl phosphate(Fe PP)was synthesized by the method of mixed hot solvent and added to EP.The results showed that Fe PP can improve the thermal stability of polymers.The UL-94 can reach the V-1 rate and the LOI was also significantly improved compared with pure EP.In order to improve the flame retardancy of composite materials,Fe PP and DOPO were compounded to study its synergistic flame retardant mechanism.It was found that the EP/3DOPO/1Fe PP nanocomposite can pass UL-94 V-0 and the LOI value was as high as 34.5 %.Reducing the HRR and the THR had a significant effect.This is mainly because Fe PP can be degraded into phosphorus and metal oxides during combustion to promote rapid carbonization of polymers.And DOPO can capture free radicals in the gas phase,inhibit the progress of chain reactions and inhibit combustion,so as to achieve gas phase and condensation Synergistic flame retardant effect.