Eco-friendly sound-proofing made from seaweed

Most of the acoustic materials that can cancel out sound are made from plastic foams that aren’t easily recycled or degraded. This is a significant environmental issue, as plastic can take centuries to decompose if they enter the environment. Moreover, current alternative options are made from plant fibres that don’t effectively dampen noise in the most useful range of sound frequencies, or are too thick or unwieldy to fabricate.

Now, researchers reporting in ACS Sustainable Chemistry & Engineering have created a biodegradable seaweed-derived film that effectively absorbs sounds in the useful frequency range. The new material could provide a more sustainable way to reduce noise pollution.

The team started with agar, a gel derived from seaweed that is often used as a culture medium for bacteria or as a thickener in food. They mixed the agar with glycerine as a plasticiser and cellulose nanofibres to create a flexible film. When tested, the film was found to effectively absorb sounds in the frequency range of human speech, which is typically between 500 Hertz and 2000 Hertz.

The team is now working on optimising the film’s sound-absorbing properties, while exploring further properties such as flame resistance. They are also considering the use of other plant-based materials. Funding for the project came from the Science and Engineering Research Board, India, and the Indian Institute of Technology Kanpur.

There are other innovations looking at the use of seaweed. Norway’s material science company B’ZEOS is working with global corporations to replace single-use plastics with seaweed-based alternatives. And UK-based Notpla is making seaweed packaging in partnership with well-known brands such as Just Eat.