Preparation And Flame Retardant Performance Of Epoxy Resin/Functionalized Titanium Dioxide Nanotubes Nanocomposites

As a common thermosetting polymer,epoxy resin?EP?has widely been applied in electronic appliances,engineering plastics,and coatings,etc.due to its excellent properties.However,EP is flammable material which is similar to most macromolecule polymers,and there is a great fire risk when using it.Therefore,improving the flame-retardant properties of EP has become an urgent problem to be solved,which has caused much more attention.This dissertation primarily focuses on improving the flame-retardant properties of EP;a variety of flame-retarded functioned TiO₂nanotubes were prepared and introduced into epoxy resin matrix with solution blending method to prepare flame retardant EP nanocomposites with excellent properties.Through the test of flame-retardant instruments,the effect of flame-retardant functionalized titanium dioxide nanotubes on the combustion performance of epoxy resin was studied,the flame-retardant mechanism was explored,and it has provided a new idea for the development of epoxy resin nanocomposites with excellent fire safety.The main research works are as follows:1.Chitosan?CH?and synthetic phosphatized chitin?PT?were constructed on the surface of TiO₂ nanotubes through the layer by layer assembly process,and phosphorus-modified titania nanotubes??CH/PT?-TNTs?were obtained.Then the EP/?CH/PT?-TNTs nanocomposites was prepared by solution blending,and the unmodified TNTs was taken as a reference.The results showed that?CH/PT?-TNTs could further improve the flame retardancy of epoxy resin matrix compared with TNTs.TEM,FTIR and XPS results demonstrated that the assembly layer consisting of CH and PT was successfully constructed on the TNTs surface.Cross-sectional SEM images of nanocomposites illustrated that the surface modification of TNTs effectively improved its dispersibility in EP.Thermogravimetric analysis and cone calorimetry results showed that the addition of?CH/PT?-TNTs could improve the thermal stability and flame retardancy of EP.The amount of 2wt%?CH/PT?-TNTs added results in the residual carbon content of 18.2%,and the PHRR was reduced by 48.8%compared to the pure sample,and the same amount of added?CH/PT?-TNTs was superior to TNTs.A possible flame-retardant mechanism has been speculated on the synergistic effect between the CH/PT assembly layer and the TNTs.On the one hand,the modification of TNTs by the CH/PT assembly layer improved the dispersion of TNTs in the epoxy resin which enhanced physical barrier of TNTs.On the other hand,the phosphorous element of the assembly layer had the effect of dehydration to carbon.At the same time,the well dispersion also benefited for promoting the contact between flame retardant and epoxy matrix,so exerting a better flame retardant effect.2.A series of Ce O₂-TNTs hybrid materials with different CeO₂ loadings were synthesized by co-precipitation method,and then incorporated into EP to prepare CeO₂-TNTs flame-retardant epoxy nanocomposites.Structure and morphology characterization indicated the successful synthesis of Ce O₂-TNTs.The effect of CeO₂-TNTs with different CeO₂ loading on the fire safety of EP was compared and analyzed by TGA,Cone and Raman.The results showed that CeO₂ loading could increase the carbon residue of nanocomposites,reduce the PHRR and THR,and improve the fire safety of EP.The residual carbon content of EP/0.1CeO₂-TNTs sample at 700°C reached 19.8%with the lowest degradation rate,and the PHRR and THR were reduced to 680 kW/m² and 32.9 MJ/m²,respectively.3.Co₃O₄-TNTs hybrid material was synthesized by co-precipitation method.?-ZrP was prepared by hydrothermal synthesis method and CTAB was intercalated to obtain OZrP.Then the synthesized nanomaterials were added to the EP matrix in a certain proportion by solution blending to prepare a series of EP nanocomposites.The morphology and structure of the synthesized nanomaterials were analyzed and the results indicated that Co₃O₄-TNTs and OZrP have been synthesized successfully.TGA results indicated that the co-addition of Co₃O₄-TNTs and OZrP could further improve the thermal stability of EP.The results of Cone showed that Co₃O₄-TNTs and OZrP had good synergistic flame retardant effect on EP and could effectively improve its flame retardancy.EP/OZrP/Co₃O₄-TNTs sample had the lowest PHRR and THR,which were reduced by 36.2%and 35.4%compared to pure epoxy resins respectively.