Study On Flame Retardant And Mechanical Properties Of Boron Phosphate/montmorillonite Epoxy Resin Nanocomposites

Epoxy resins(EP)have excellent mechanical properties,adhesion properties and electrical insulation properties.They are widely used in laminates,packaging materials and used as based resin in electrical and electronic components and coating.But the epoxy resin must be fire-retardant treatment when application in order to improve the fire safety.Because of their high efficiency,halogenated flame retardants have been widely used.However,they will release a lot of smoke and toxic gases during combustion,there exists a potential threat to humans and environment.So the research of efficient,environmentally and friendly flame retardant has become a new direction.The boron phosphate(BP)which belongs to solid acid catalyst,can catalytic polymer into carbon,while improve the stability of the carbon layer.Because of its water-insoluble,high thermal stability,low cost and environmentally friendly features,BP becomes a promising substitute for the halogenated flame retardant.Montmorillonite(MMT)belongs to the class of layered aluminosilicate clay nanofiller,could form a layered structure which could insulate heat and mass in the combustion process.What’s more,the MMT could increase the strength and toughness of polymer nanocomposites.So combination the catalytic flame retardant and nano-technology has practical significance in the exploration of environmentally friendly and efficient flame retardant and promote the sustainable development.Therefore,this thesis attempts to combine BP and MMT to improve the flame retardant of epoxy resin.Researches in this thesis are listed as followed.(1)The flame retardant epoxy resin composite(EP/BP/MMT)was prepared by physical blending method with BP and MMT.BP as the flame retardant,while MMT as the synergist.Three kinds of different MMT have different impact on composites,but with the same trend.MMT improves the LOI value of EP/BP/MMT composites,but reduces the UL 94 vertical flame test levels.MMT promotes the formation of char in early combustion,so MMT prolonged ignition of the composites and decreased HRR,MMT and BP show good synergistic effect.But as the combustion,they showing the anti-synergistic effect,therefore THR of composites increased finally.(2)With a new flame retardant BP-MMT as a flame retardant additive,the flame retardant EP/BP-MMT composite was prepared.While the BP-MMT was prepared by chemical method with BP and MMT,and the BP loaded on the MMT sheets.The results show that,BP-MMT can increase the LOI value of the epoxy resin,and the UL 94 vertical flame test could reach V-1 level.Significantly reduce the peak of heat release rate(PHRR)and total heat release(THR)during combustion.During the combustion,the catalysis effect by BP and the barrier effect by MMT were happened at the same time.(3)Compared with EP/BP composite,the addition of MMT could reduce the initial thermal decomposition temperature of EP/BP/MMT composites,so the pyrolysis carbonization could happened at lower temperature.But the MMT would influence the crosslink reaction between BP and pyrolysis products of EP,resulting in the decrease of the char residue.Then,the addition of BP-MMT composite also reduced the initial thermal decomposition temperature of EP/BP-MMT composite and increased the char residue.The BP-MMT composite could improve the thermal stability of the EP composite slightly.(4)Compared with EP/BP composite,the addition of MMT could improve the tensile strength and flexural strength of EP/BP/MMT composites,which OMMT improve more significantly.Compared with EP/BP/MMT composite,which was prepared by physical blending method with the same quality of BP and MMT,the EP/BP-MMT could improve the compatibility and interfacial adhesion between inorganic flame retardant and EP.As a result,the mechanical properties of EP/BP-MMT composite was better than EP/BP/MMT composite.