Preparation Of Nano-copper Oxide And Its Synergistic Flame Retardant Effect With Ammonium Polyphosphate In Epoxy Resin

This paper is based on the background that epoxy resin?EP?is widely used in lightweight materials for high-speed trains.Aiming at the problem that EP is flammable and releases a large amount of toxic smoke during combustion,the nano-copper oxide loaded by expanded graphite?CuO@EG?flame retardant synergist was prepared by co-calcination method.And the effects of preparation conditions of CuO@EG on the particle size distribution and content of copper oxide in the product were investigated.Then CuO@EG and ammonium polyphosphate?APP?were introduced into EP together,and the effect of preparation conditions of CuO@EG on its flame retardant synergistic effect was studied by orthogonal design.Based on this,a high flame retardant and low smoke toxicity epoxy resin was prepared.Finally,the fire behavior of the flame retardant epoxy resin was studied by cone calorimeter from three aspects:heat release performance,smoke generation performance and smoke toxicity.Meanwhile,the flame retardant and smoke toxicity reduction mechanism of CuO@EG synergistic APP on EP were discussed.The research results obtained are as follows:1.Nano-copper oxide loaded by expanded graphite?CuO@EG?flame retardant synergist was successfully prepared by co-calcination using copper acetate?Cu?Ac?₂?and graphite intercalation compounds?GICs?as raw materials,and The microstructure was characterized by scanning electron microscopy?SEM?,and the results show that the average particle size and content of CuO increased with the increase of Cu?Ac?₂/GICs mass ratio,calcining time and calcining temperature.The Cu?Ac?₂/GICs have a mass ratio of 0.5,a calcination time of 1 min,and a calcination temperature of 400?.The average particle size of the nano-CuO is the smallest,which is 82.3 nm2.CuO@EG and APP were introduced into EP together,and a high flame retardant and low smoke toxicity epoxy resin was successfully prepared.The synergistic flame retardant effect of CuO@EG and APP in EP was the best under the conditions of Cu?Ac?₂/GICs mass ratio of 2:1,calcination temperature of 400?and calcination time of 5 min.Compared with EP/20%APP,the EP/14%APP/6%CuO@EG sample increased the LOI from 30.0%to 33.6%,and the UL-94 rating increased from NR?no grade?to V-0.3.The fire behavior of the high flame retardant low smoke toxicity epoxy resin materials was studied by cone calorimetry from three aspects:heat release performance,smoke production performance and smoke toxicity.It was found that the introduction of CuO@EG synergistic APP further reduced the heat release performance,smoke production performance and toxicity of major harmful gases?CO?of EP,and effectively reduced the overall fire risk of EP.The peak heat release rate of EP/14%APP/6%CuO@EG sample was450.0kW/m²,the peak smoke production rate was 0.174m²/s,and the peak CO release rate was 0.0196g/s,which were reduced by 15.0%,26.3%,and 31.5%compared to EP/14%APP/6%EG,respectively.4.The mechanism of CuO@EG reducing fire hazard of EP was studied by analyzing the heat release performance,smoke generation performance,smoke toxicity and char residue morphology of neat EP and high flame retardant low smoke toxicity epoxy resin samples.On the one hand,CuO@EG can participate in the process of carbonization to synergize APP to play a condensed phase flame retardant effect,improve the integrity and compactness of the carbonized layer,thereby suppressing the release of smoke particles,heat transfer and the release of combustible pyrolysis products in the pyrolysis area of EP matrix,and greatly reducing the amount of heat released and smoke production by combustion.On the other hand,CuO@EG can catalytically oxidize the toxic gas CO produced by incomplete combustion of EP to CO₂,reducing the CO concentration of the released flue gas,thereby reducing the toxicity of the flue gas.