Sparks fly on an illuminating evening
Cambridge & Great Eastern Regional Group: Evening science lecture Cambridge University, UK
 What better way to spend a blustery early November evening than to come along to the University of Cambridge’s department of chemistry and enjoy a lecture on the science of fireworks? This year the lecture was presented by Jacqueline Akhavan (below, right), a chemist involved in research and development of commercial fireworks, pyrotechnics and high explosives. Practical demonstrations were ably provided by her husband.
Akhavan, a senior lecturer at Cranfield University in the department of environmental and ordnance systems, explained the fundamental principles of explosives, and then described how the various colours, noises and effects are achieved in fireworks. We experienced brilliant flashes of red (due to strontium), green (barium), orange (sodium) and blue (copper – the hardest to achieve because of temperature criticality). She explained how metals, in particular titanium, aluminium, magnesium and iron, can be used to create crackles, flashes and sparks.
| ‘We experienced brilliant flashes of red (due to strontium), green (barium), orange (sodium) and blue (copper) – the hardest to achieve because of temperature criticality’ |
The various constructions of fireworks can provide startlingly different effects. We were shown how the packing of the explosive material can alter the rate of burning, create noise and give different phases of the firework. These concepts were illustrated with sparklers, catherine wheels, fountains and roman candles. Loud whistlers and bangers were demonstrated, and several rockets were set off (thankfully, restrained in a special device).
She finished by talking about fireworks of the future. One she demonstrated produced a spectacularly bright strobe effect. Interestingly, its mode of action remains unclear (as is that of the whistling rockets). Her research team is also looking at safer manufacturing processes and materials, and more environmentally friendly systems.
Safety was emphasised and observed at all times during the lecture, most fireworks being set off behind a clear screen.
Akhavan was careful to emphasise the potential dangers of explosives and the importance of observing the fireworks code.The lecture was attended by over 300 people, including many families and several school parties. We emerged from the lecture a little smoky, but with a much better understanding of the chemistry that goes into our bonfire night fireworks.
Akhavan has written a book for the Royal Society of Chemistry, The Chemistry of Explosives, and has published over 60 papers. Other areas of research include semi-conducting polymers, electrorheological fluids and recycling of polymeric waste.
John Wilkins
SCI CaGE Regional Group
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