Flame Retard Modification Of Epoxy Resin By Carbon Nanotubes Functionalized With Phosphorus-Containing Compound

Epoxy resin is widely used in many fields as it has excellent cohesive power and mechanical properties, but its brittleness and poor flame retardant property limit its use in more demanding fields. With excellent mechanical properties,electrical properties and thermal properties, the carbon nanotubes have been used in the modification of polymer since they were discovered. In this paper, multi-wall carbon nanotubes(MWCNTs) was functionalized on the surface, so they can be ensure evenly dispersed in the epoxy resin matrix and effectively improve the property of the two phase interface. The prepared composite material has excellent mechanical properties and flame retardance. The effects of the surface functionalized MWCNTs on the mechanical properties and flame retardance of epoxy resin composites were investigated.Multi-walled carbon nanotubes (MWCNTs) were oxidized by mixed acid, and then were functionalized by phosphorus-containing compound 2-(6-oxido-6H-dibenz<c,e><1,2> oxa phosphorin-6-yl)-1,4-dihydroxy phenylene (DOPO-HQ). The functionalized carbon nanotubes (MWCNTs-P) were used to modify epoxy resin.First of all, the analysis results of non-isothermal curing dynamics of MWCNTs-P/EP composites showed that the addition of MWCNTs-P accelerated the rates. Secondly, the effects of MWCNTs and MWCNTs-P on mechanical properties and dynamic mechanical analysis of epoxy resin were compared.The results showed that, both of MWCNTs and MWCNTs-P can improve mechanical properties of epoxy resin, while MWCNTs-P possess better modification effect. When the MWCNTs-P content was 0.5%, the impact strength of the epoxy resin composites increased by 232%. SEM images showed that the addition of carbon nanotubes improved the toughness of epoxy resin. The tests of tensile properties and bending performance of the composites indicated that the best content of MWCNTs-P was 1.00%.Dynamic mechanical analysis results showed that MWCNTs-P improved storage modulus and glass transition temperature (Tg) of the composites. Finally, Limiting oxygen index (LOI) of the composites test revealed that MWCNTs-P can improve the flame retardancy of epoxy resin, and when MWCNTs-P content was 0.5%, the LOI reached to 30.2%.