Study On Catalytic Smoke Suppression Of Hybrid Polymer Loaded With Ag Nanocrystals In Flame-retardant Epoxy Resin

As a thermosetting material,epoxy resin is widely used in integrated circuits,aerospace and other fields.However,the flammability of epoxy resin increases the fire risk of use and restricts the large-scale application.In this thesis,we synthesized organic-inorganic hybrid nanoparticles TTD@Ag containing nitrogen,phosphorus,and silver through a general method,and applied it to the modification of epoxy resin(EP).We investigated the flame-retardant properties,thermal properties,mechanical properties,and dielectric properties of the composites formed by epoxy resin and TTD@Ag(EP/TTD@Ag composites),and explored the effect of Ag nanocrystals on epoxy resin.Then analyzed the flame-retardant mechanism of the system.The specific research contents are summarized as follows:(1)Based on Kabachnik-Fields reaction,2,4,6-tris(4-aminophenyl)-1,3,5-triazine(TAA),terephthalaldehyde(TPA),9,10-dihydro-9-oxa-10-phosphaphenanthrene-10oxide(DOPO)were used as raw materials to introduce triazine ring,schiff base,DOPO and other moieties into the polymer framework to synthesize hybrid polymer spheres TTD.Taking polymer spheres as a carrier and silver nitrate as a metal source to reduce Ag nanocrystals on the surface of the spheres,then organic-inorganic hybrid nanoparticles TTD@Ag were prepared.The structure,composition and morphology of the hybrid nanoparticles TTD@Ag were characterized by XRD,TEM,XPS and other tests.Thermogravimetric analysis was used to study the thermal stability of the hybrid nanoparticles.The results show that the prepared hybrid polymer TTD is spherical particles with uniform particle size,about 200-300 nm,and the carbon residue rate of hybrid nanoparticles,which Ag nanocrystals incorporated with 1.24 at.%,increases by 13.9%.(2)Adding hybrid nanoparticles TTD@Ag into epoxy resin to prepare EP/TTD@Ag composites.The flame-retardant performance of the modified epoxy resin was comprehensively evaluated through testing methods such as LOI,UL-94 vertical combustion,and cone calorimetry test.The results suggest that the LOI value of the modified epoxy resin is greatly increased,and the maximum LOI value can be up to 35%.The vertical combustion grade of the composite,doped with TTD@Ag by 3 wt.%,can reach the V-0 level,and compared to pure epoxy resin,the peak of heat release rate and total heat release for the composite are all decreased.In addition,due to the presence of Ag nanocrystals,the smoke production rate and total smoke production of the composite are effectively reduced,and the CO production is reduced by 31.05%,indicating that Ag nanocrystals can exert excellent smoke suppression and toxicity reduction effects.(3)Exploring the influence of different amounts of TTD@Ag on the other performance for EP/TTD@Ag composites.The results illustrate that within a certain addition range,as the amount of hybrid nanoparticles increases,the glass transition temperature of the composites raises,so does the carbon residue rate.What’s more,the storage modulus is increased by a maximum of 38.16%,and the flexural modulus,as well as the bending strength,is increased,while the loss factor is reduced,exhibiting that the stiffness and toughness of epoxy-based composites are enhanced,and the mechanical properties are improved.In addition,under the appropriate amount of addition,the dielectric constant and dielectric loss factor of epoxy-based composites are lower than those of pure epoxy resin.