Self-assembling molecules inhibit fuel fires


Researchers in the US have created a safer jet fuel—less likely to catch fire in a crash than conventional jet fuel—but which burns just as well in engines.

Chemists from the California Institute of technology, (Caltech) and NASA’s Jet Propulsion laboratory have discovered an additive that reduces the fuel’s tendency to form a mist in an accident.

The additive is a polymer, made up of large molecules with many repeating sub-units. Individual polymer molecules link into long chains known as megasupramolecules.

Caltech professor, Julia Kornfield, says these ultra-long molecules inhibit post crash misting, but allow fuel to form a combustible mist when injected into an engine. Previous long-chain polymers added to fuels broke down when passing through fuel pumps, lines and filters, limiting their usefulness when pumped into aircraft fuel tanks. The megasupramolecules rejoin after passing through these obstacles, allowing the fuel to recover its anti-misting properties.

Experiments used a projectile to smash a container of fuel near burning gas torches. The untreated fuel formed a fine mist that ignited after less than a tenth of a second. The treated fuel did not ignite.

The additive changes a fuel’s flow behaviour without affecting its other properties, such as energy content, surface tension and density, which are unchanged; tests with diesel engines showed no change in power output.

Kornfield says the next step will be to develop a way to produce the polymer in bulk. ‘Above all, we hope these new polymers will save lives, and minimise burns that result from post-impact fuel fires,’ she said.

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