Abstract

Fire hazards including the generation of heat, smoke and toxic vapor, cost a great number of lives and damage properties. Compared with natural polymers, the high flammability and the widespread use of synthetic polymers lead to serious safety and environmental problems. Therefore, methods to flame retard polymer materials have attracted much interest.

Metal organic frameworks (MOFs), as a new class of porous materials show promising properties in many areas. The hybridization of MOF with other functional materials, and the post synthetic modifications of MOF can provide materials with fire retardant elements such as nitrogen, phosphide. Polymers with an enhanced fire retardancy property can be achieved.

In this work, hierarchically nano structure MOF/GO and Ag/MOF/GO are synthesized successfully. The morphology of composites was observed by SEM and TEM. According to the FITR spectrum, the significant decrease of peaks from C=O bonds indicated that the reaction between MOF and GO is from the coordinate bonds rather than physical anchoring. The peaks resulting from Ag and MOF were obtained from XRD and showed the existence of silver particles without the destruction of MOF crystals. Next, nanofillers were incorporated into epoxy with the use of a three-roll mill. The fire retardancy property of epoxy nanocomposites are investigated by the cone calorimeter tester and limiting oxygen index (LOI). Among all the samples, the MOF/GO EP sample showed the best fire retardancy property. The pHRR of MOF/GO EP decreased by 30 % and its LOI value increased from 23.8 (epoxy resin) to 30. The significant increase of fire retardancy attributed to the barrier effect of graphene oxide, catalytic carbonization process of MOFs and the formation of the char layer. SEM and Raman results confirmed that a compact structure with fewer pores char layer formed. Also, the thermal stability and dynamic property were tested by TGA and DMA. All the samples except the one with the addition of only rGO showed a significantly lower maximum degradation rate from TGA.