Materials

World’s lightest sound insulator could radically reduce jet engine noise

World’s lightest sound insulat...
Professor Michele Meo, from Bath's Materials and Structures Centre, led the research on this ultralight aerogel
Professor Michele Meo, from Bath's Materials and Structures Centre, led the research on this ultralight aerogel
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Professor Michele Meo, from Bath's Materials and Structures Centre, led the research on this ultralight aerogel
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Professor Michele Meo, from Bath's Materials and Structures Centre, led the research on this ultralight aerogel
This graphene oxide-polyvinyl alcohol aerogel weighs just 2.1 kg per cubic meter, making it the lightest acoustic insulation ever manufactured
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This graphene oxide-polyvinyl alcohol aerogel weighs just 2.1 kg per cubic meter, making it the lightest acoustic insulation ever manufactured

This graphene-based aerogel is the lightest sound insulation material ever manufactured, say researchers at the University of Bath, who have demonstrated its ability to damp down noise by up to 16 decibels despite weighing just 2.1 kg per cubic meter (0.13 lb per cubic foot).

You might not think weight is that much of a factor with acoustic foams, but to put this aerogel's density in context, compare it to a conventional polyester urethane sound absorber like Kinetics KUA, which was "developed to absorb maximum acoustical energy using minimum weight and thickness" with a density of 32 kg/m3 (2 lb/ft3). So in a given application, this new "graphene oxide-polyvinyl alcohol aerogel," squeezed into a Nomex honeycomb, would weigh less than one-fifteenth of an equivalent traditional acoustic foam installation.

Nowhere is weight so critical as in aerospace, and the Bath team has identified aircraft engine nacelle insulation as a key potential market for the technology, putting forth the example that it could potentially reduce the cabin noise of a jet airliner from the current 105-dB roar to something closer to a 95-dB hairdryer.

This graphene oxide-polyvinyl alcohol aerogel weighs just 2.1 kg per cubic meter, making it the lightest acoustic insulation ever manufactured
This graphene oxide-polyvinyl alcohol aerogel weighs just 2.1 kg per cubic meter, making it the lightest acoustic insulation ever manufactured

“This is clearly a very exciting material that could be applied in a number of ways – initially in aerospace but potentially in many other fields such as automotive and marine transport, as well as in building and construction," says Professor Michele Meo, who led the research. "We managed to produce such an extremely low density by using a liquid combination of graphene oxide and a polymer, which are formed with whipped air bubbles and freeze-casted. On a very basic level, the technique can be compared with whipping egg whites to create meringues – it’s solid but contains a lot of air, so there is no weight or efficiency penalty to achieve big improvements in comfort and noise.”

In their paper, the researchers say they believe the aerogel will have other useful properties, including fire resistance and electromagnetic shielding, and there's also the potential to develop it further to optimize its heat dissipation capabilities, which would be very handy in engine insulation. The team says it could be commercialized and in use within 18 months.

The research is open access in the journal Nature Scientific Reports.

Source: University of Bath

9 comments
9 comments
Chris__
What is the comparable dB reduction of the conventional polyester urethane sound absorber? Is this material only useful for aerospace where no acoustic insulation can be used due to weight constraints?
CAVUMark
Sure could use this on my common wall! Great ideas, time to commercialize.
niio
How durable is it? If it crumbles and dumps abrasive particles into the turbo engine it won't be very popular.
Kevin Ritchey
How does it hold up over time, vibration, exposure to airborne oxidation and toxins?
eirobotix
Knowing what frequency ranges is it effective in would be nice
Dan Lewis
Chris - Did you not read the article? It was clear about the material having other uses.
niio - Do you really think they haven't looked into the questions you pose?? Really? Come on!
Simon McCombe
Advancements like this are great, though what I would like to see is improvement in making cheaper (and fire resistant, non-toxic) sound insulation. Many construction companies like to cut costs and one of the first things they skimp on when throwing up apartments is sound proofing.
Bob Siegel
Sounds like quantum jump.

As to the engine being fouled by fragmentation ...,

There are inner and outer liners in jet engines,: the compressor / fuel ignitions side, and the outer streamlined failings?

Unless something has changed in the last couple minutes when a 747 went over my house?
Tag
I'd personally love to see more sound insulation used in cars.