| Due to the flammable properties of epoxy resin（EP）,there is a huge fire hazard.Therefore,improving the flame retardancy of epoxy resin has become the goal of research.Nowadays,inorganic flame retardant is still one of the widely used flame retardants,but its application range is greatly limited due to its poor interfacial compatibility with organic polymers and large addition amount.Therefore,maintaining a certain level of mechanical properties while improving the comprehensive flame retardancy of EP has become an urgent problem to be solved.Metal Organic Frameworks（MOFs）are a class of materials with both organic and inorganic components.The inorganic phase has a certain degree of flame retardancy and smoke suppression,while the organic phase retains good compatibility with the substrate.However,MOFs materials themselves tend to pile up and gather,resulting in uneven composite materials.The inorganic SiO2in the silicon based flame retardant has the characteristics of easy loading,uniform particle size,stable dispersion,and easy synthesis and convenient particle size control.Therefore,this thesis uses SiO2/MOFs based hybrids as flame retardants for innovative research,and proposes flame retardant mechanisms.In order to improve the inherent flammability of epoxy resin and alleviate the problems of poor interfacial compatibility and easy aggregation caused by inorganic flame retardants,a new type of multicomponent synergistic green flame retardant SiO2/PANI/ZIF-67 based on SiO2/MOFs was successfully synthesized by using electrostatic interaction and chemical bonding methods to load polyaniline（PANI）and ZIF-67 on the surface of 500 nm SiO2,respectively.The results showed that only 6%SiO2/PANI/ZIF-67/EP had a limiting oxygen index（LOI）of 28.0%,and the peak heat release rate（p HRR）,total heat release（THR）,total smoke production（TSP）,and total CO production（TCOP）decreased by 22.59,44.06,45.05,and 44.05%,respectively.The residual weight rate increased by 5.8%.It has been verified that there is a synergistic effect between PANI and ZIF-67,which promotes the accumulation of carbon particles and SiO2on the surface of the substrate,forming a SiO2-C barrier layer containing metal ions on the surface of the material,thereby reducing the emission of heat,smoke,and toxic gases.In terms of mechanical properties,there is a strong interfacial binding force between the organic portion of the flame retardant surface ZIF-67 and the epoxy resin,reducing the loss of mechanical properties caused by a single inorganic flame retardant.Due to the limited improvement of flame retardant SiO2/PANI/ZIF-67 on the p HRR and residual weight ratio of EP composites,and the decrease in mechanical properties.Therefore,it is further optimized for these points.A new type of green synergistic flame retardant SiO2/Co Ni-DH-PA（SiO2/Co Ni layered bimetallic hydroxide）based on SiO2/MOFs was successfully prepared by introducing Ni and phytic acid（PA）through ion exchange and chelation.The results showed that the residual weight rate of5%SiO2/Co Ni-DH-PA/EP increased from 15.05%（pure EP）to 24.40%,and the proportion of p HRR,TSP,and TCOP decreased was 63.78,31.88,and 63.74%,respectively.It has been verified that there is a synergistic effect between flame retardants,and the carbon promoting effect of PA greatly increases the residual weight ratio.Bimetals exhibit stronger catalytic carbonization than single metals,resulting in a denser carbon layer formed on the surface of the material,greatly reducing the release of CO,thereby improving the comprehensive flame retardancy of EP composites.In terms of mechanical properties,due to the good interfacial effect between PA and the matrix,the mechanical strength of epoxy resin composites is improved. |
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