| Epoxy resin is a kind of thermosetting polymer material,due to its excellent adhesion,good corrosion resistance,excellent electrical insulation and other excellent properties,it has become a widely used material in various industries.However,epoxy resin is a flammable material,which is easy to cause fire in practical applications,and has relatively large limitations.In order to reduce the probability of fire,flame retardants must be used to improve the flame retardancy of epoxy resins.At present,from the perspective of environment and safety,in order to solve the problem that the existing flame retardant materials are harmful to the burning process,it is urgent to develop new environmentally friendly flame retardants.In this paper,para-phenylene diamine,2-hydroxy benzaldehyde and9,10-dihydro-9-oxa-10-phosphine-10-oxide(DOPO)were used as raw material to prepare a new phosphorus-nitrogen flame retardant SP-DOPO by two steps reaction.Firstly,para-phenylene diamine reacted with 2-hydroxy benzaldehyde to prepare SP;Then,the SP reacted with DOPO to prepare a novel phosphorus-nitrogen flame retardant SP-DOPO.FTIR,XRD and SEM were used to character and analyze the structure,morphology and phase of flame retardant chemical.The effects of reaction time and reaction temperature on the synthesis were studied and optimum reaction conditions were ensured.The optimal synthesis process was determined as follows:para-phenylene diamine and 2-hydroxy benzaldehyde reacted at 50?for 3 hours to prepare SP,then SP and DOPO reacted at 80?for 6 hours to prepare SP-DOPO.0g,5g,10g,15g of SP-DOPO and a certain amount of curing agent m-phenylenediamine(MPD)were added to 100g of epoxy resin respectively to prepare phosphorus-nitrogen flame retardant epoxy cured product.Flame retardancy of epoxy resin was preliminarily evaluated by limiting oxygen index determination,scanning of carbon residue and determination of thermal properties.It was found that the addition of SP-DOPO increased the limiting oxygen index of epoxy cured product from 22.6 to 28.2.However,the epoxy cured material becomes more brittle and its ductility decreases.Among them,the breaking strength and elongation at break of the epoxy cured product added with 5g SP-DOPO decreased by 8.23MPa and 2.84%,respectively.The tensile property of the epoxy cured product added with 15g SP-DOPO was the worst.In order to improve the mechanical properties of the flame retardant epoxy resin system on the premise of ensuring the flame retardant properties of the flame retardant epoxy resin system,SP-DOPO and nano aluminum hydroxide were used in combination and added to epoxy resin to prepare composite flame retardant epoxy curable.Flame retardancy of epoxy resin was evaluated by limiting oxygen index determination,scanning of carbon residue and determination of thermal properties.The experimental results show that when the addition amount of nano Al(OH)3 and phosphorus-nitrogen flame retardant SP-DOPO in 100g epoxy resin are both 7.5g,the limiting oxygen index reaches the maximum and the maximum value is 28.9.Control the total addition amount of flame retardant in 100g epoxy resin to 15g,at this time the breaking strength and breaking elongation of the composite flame retardant epoxy cured product is higher than that of the phosphorus nitrogen flame retardant epoxy cured product This shows that nano Al(OH)3 can improve the mechanical properties of epoxy resin to some extent while synergistic with SP-DOPO flame retardant epoxy resin. |
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