Carbon nanotubes provide self-extinguishing grade to silicone-based foams

This article examines the feasibility of using multiwall carbon nanotubes (MWCNTs) as a fire retardant in silicone- based foams. MWCNTs were mechanically blended with polydimethylsiloxane reactants without any previous functionalisation treatment. The flammability of the materials was characterised as a function of the filler content using a standard fire testing method. The limiting oxygen index of the composite increased as a function of nanotube content, attaining the self-extinguishing grade even at low mass fraction of the carbon nanotubes (0.5 wt%). Further thermal characterisation revealed increases in thermal dissipation efficiency and thermal degradation temperature. The different thermal and flame retardancy results were attributed to the formation of a CNT network throughout the sample. The formation of this network was attributed to a good dispersion of the CNTs via non-covalent CH-pi interactions and to the surface tension of the gas-polymer interface during foaming.