Phosphorus-filled nanobrick wall multilayer thin film eliminates polyurethane melt dripping and reduces heat release associated with fire
Upon exposure to fire (or other forms of extreme heat), polyurethane decomposes into polyol and isocyanate components, which form highly flammable melt-pools and release volatile, toxic gases. Typical layered-silicate polymer nanocomposites combat fire in the condensed phase, where the MMT platelets strengthen the fire blocking residue and provide a shield heat. Thermal shielding afforded by these ~30 nm thick films was solely provided by the presence of the inorganic clay platelets. In the present study, it only takes 4 TL of the PSP/PAH/MMT nanobrick wall assembly (< 3 wt% coating addition) to cut the pkHRR of polyether-based PU by 54.8%. TL coatings (< 20 nm thick). Most thin films prepared via layer-by-layer assembly use an even number of deposited layers, which adds to the uniqueness of the present three-component nanocoating. This trilayer deposition, which combines two common flame-retarding mechanisms (thermal shielding clay and intumescing PAH/PSP) in a single coating system sequence, allows the polymeric component to play a more active role in the FR behavior of the traditional nanobrick wall architecture. There is now additional ability to tailor the properties of this new class of environmentally-benign FR treatment. These thin, water-based nanocoatings proved a tremendous opportunity to protect the complex substrates found in upholstered furniture, clothing and the transportation industry.
Cain, AA; Nolen, CR; Li, YC; Davis, R; Grunlan, JC; Polym. Degrad Stab., 2013, 98 (12), 2645-2652.