Construction Of Boron Nitride Based Flame Retardant System And Study On Fire Safety Performance Of Epoxy Resin Coating Materials

Aiming at the problem that epoxy resin（EP）is flammable,and a large amount of heat and toxic smoke from fire are released during the combustion process of EP,novel boron nitride（BN）based flame retardant systems and its flame retardant EP composite coating materials were designed and constructed by means of co-precipitation-thermal oxidation method,chemical reaction and self-assembly strategy.The influence rules and mechanism of BN-based flame retardant systems on the fire safety performance of EP composite coating materials were discussed.The main research contents are as follows:1.Cobalt-iron prussian blue analogue（Co Fe-PBA）crystals were in-situ grown on BN matrix by co-precipitation method,and the organic ligands were etched by thermal oxidation strategy to prepare BN@Co Fe O_x micro-nano structural materials.Co Fe O_x in BN@Co Fe O_x micro-nano structural materials was mainly loaded on the surface of BN in the form of hollow cubic skeleton and nanoparticles.It is found that BN@Co Fe O_xhas good dispersion in EP and can significantly enhance the flame retardant and thermal conductivity of EP.Compared with pure EP,the peak heat release rate（p HRR）,total heat release rate（THR）,peak smoke production rate（p SPR）and total smoke production（TSP）of EP/BN@Co Fe O_x 2.0 composite coating materials decrease by 44.7%,42.7%,54.8%and 56.2%,respectively.The limiting oxygen index（LOI）value increases from24.2%of EP to 34.3%,and the vertical combustion test（UL-94）is V0 grade.The BN@Co Fe O_x micro-nano structure material improves the thermal stability of the EP composite coating materials by changing the carbon layer structure.In addition,BN@Co Fe O_x micro-nano structure materials enhance the thermal conductivity of EP composite coating materials.At the same cooling time,the center temperature of EP/BN@Co Fe O_x composite coating materials decrease by 56.3%compared with the initial temperature,while the center temperature of EP decreases by only 48.8%.The heat conduction channels and networks constructed by BN@Co Fe O_x in EP greatly promote heat transfer.2.BNO@IL organic-inorganic nanomaterials with nanoflower morphology were synthesized by using hydroxylated boron nitride（BNO）,silane coupling agent（KH-560）and ionic liquid（[APMIm][PF₆]）as raw materials.It is found that there is good interfacial interaction between BNO@IL organic-inorganic nanomaterials and EP matrix.Moreover,BNO@IL organic-inorganic nanomaterials can significantly improve the thermal stability and fire safety performance of EP.EP/BNO@IL-2.0 nanocomposite coating materials show the best flame retardant and smoke suppression performance in all samples,and its fire growth index（FGI）is the lowest.Compared with pure EP,p HRR,THR,p SPR and TSP are reduced by 48.6%,30.3%,40.7%and 51.9%,respectively.Secondly,the residual char content of EP/BNO@IL-2.0 nanocomposite coating material increases by 92%.The organic-inorganic nanomaterials of BNO@IL catalyze EP to form graphitized carbon layers and nano-barrier networks in EP to block the heat and mass exchange between the underlying EP matrix and the combustion zone,thereby reducing the fire hazard caused by the combustion of EP.3.Based on the principle of electrostatic interaction,phytic acid doped BN nano-layered hybrid（OBN-P-PA）was constructed by self-assembly strategy.It is found that the OBN-P-PA nanohybrids present layered structure with rough surface and curled edges,promote the curing of EP and have strong interfacial interaction with EP matrix.In addition,the heat,smoke and toxic gas release of EP/4 OBN-P-PA nanocomposite coating materials are significantly lower than those of pure EP,in which p HRR,smoke factor（SF）and peak carbon monoxide formation rate（p COPR）are reduced by 40.1%,45.3%and 39.7%,respectively,accompanied by the increase in glass transition temperature（T_g）and flexural modulus.OBN-P-PA nanohybrids catalyze EP to form graphitized and dense carbon layers,and thus improve thermal stability and heat resistance of EP under the high temperature.On the other hand,OBN-P-PA nanohybrids form tortuous paths in EP,which slows down the transmission speed of heat and pyrolysis products,effectively inhibits the release of heat and smoke during the combustion of EP,and improves the fire safety performance of EP.