Preparation Of Inorganic-organic Hybrid Flame Retardant And Its Application In Epoxy Resin

Epoxy resin（EP）has been widely used in the fuselage and interior decoration of civil aircraft due to its excellent adhesion,corrosion resistance and machining performance.However,it has the disadvantages of easy combustion,large heat release and large smoke production,so it needs to be modified to be flame retardant.In this paper,two inorganic-organic hybrid flame retardants were designed and prepared,and their effects on the thermal stability and combustion performance of EP were studied,which provided a research basis for the flame retardant technology of EP.The curing reaction kinetics,curing method and combustion performance of EP were studied.The results showed that the activation energy of EP increased slightly from 51.94k J/mol to 52.84 k J/mol when the addition of graphene was 3 wt.%,and the addition of graphene had little effect on the curing reaction of EP.The curing process of EP was obtained as follows:reaction at 80℃,120℃,150℃and 180℃for 2 h.According to the experiment and calculation,the appropriate dosage of curing agent is 0.41 g/g.In the combustion process of EP,there are a lot of heat release and smoke production,so it is necessary to carry out flame retardant treatment.Graphene-based phosphorus grafted titanium hydroxide modified graphene（PTi G）was prepared by chemical deposition and grafting,and the thermal stability and combustion performance of PTi G/EP were studied.Compared with pure EP,when the amount of PTi G was10 wt.%,the carbon residue rate of EP in nitrogen increased from 26.3%to 31.3%.Its THR and p FIGRA were reduced by 26.2%and 31.1%,respectively,and its UL94 vertical combustion test has reached V-1 level.Pyrolysis tests and carbon residue characterization of PTi G/EP showed that PTi G could block EP pyrolysis and play a gaseous flame retardant role by releasing water molecules and phosphorus-containing free radicals.The expansion flame retardant cyclodextrin phosphate melamine salt（PCDM）was prepared from cyclodextrin,phosphoric acid and melamine.The thermal stability and combustion performance of PCDM/EP were studied.The results show that UL94 vertical combustion test of PCDM/EP reaches V-0 level.When the content of PCDM is 10 wt.%,the flame retardant EP has excellent flame retardant and smoke suppression properties,under the condition of nitrogen,its initial thermal decomposition temperature and carbon residue rate were increased by 7.2℃and 19.4%respectively.Its THR and TSP were reduced by 55.5%and61.8%,respectively.The pyrolytic analysis of PCDM/EP and the characterization of carbon residue showed that PCDM/EP combustion generated flame retardant expansion carbon layer,and the pyrolytic phosphorous free radicals and NH₃ played a flame retardant role.