Making plant fibres flame-retardant might make them fly

There is renewed interest in natural materials, as recyclability and environmental safety become more important in manufacturing and consumables, writes MSc candidate Tshepiso Princess Molaba of the Nelson Mandela Metropolitan University.This article is part of the Mail & Guardian’s Science Voices series. 

 

It looks like a sleek car dashboard, but under its smooth surface flax fibres criss-cross through a three-dimensional matrix to reinforce it, making it stronger and lighter than traditional materials.

The use of natural fibres in composite applications is gaining popularity in many areas, and particularly the automotive industry. Daimler-Benz in Germany has been using the components made from different natural-fibre composites since 1994. Flax and other natural fibres are used to make 50 Mercedes-Benz E-class components. Similarly, the seat shells and their panelling are made from the latest in natural-fibre composite technology. Toyota developed a biodegradable plastic made from starch extracted from sweet potatoes and other plants. This plastic was combined with natural fibres for use in interior parts.

Flax, with its hip-height glossy bluish-green leaves and pale blue flowers, is a fiber crop that is grown in cooler regions of the world. Credit: https://upload.wikimedia.org/wikipedia/commons/6/6b/Flax_flowers.jpg

Flax, with its hip-height glossy bluish-green leaves and pale blue flowers, is a fiber crop that is grown in cooler regions of the world. Credit: https://upload.wikimedia.org/wikipedia/commons/6/6b/Flax_flowers.jpg

But the high moisture absorption and flammability of these composites has restricted their use in cars and other industries such as aerospace. This is why at the Council for Scientific and Industrial Research’s Port Elizabeth campus, in collaboration with Nelson Mandela Metropolitan University, we are researching strategies to make biocomposites safer and so increase the ways in which they can be used.

Traditional composites — which are materials made of at least two other materials — use synthetic fibres, such as glass, carbon and aramid, to make them hard and strong. But there are serious drawbacks: they are not biodegradable, consume a lot of energy to manufacture, and result in airbone fibres that cause respiratory problems. Airborne fibres are caused when sufficient amount of glass fibres are released into the air during manufacture, handling and aircraft fires.

So people are turning to natural fibres to avoid these problems. Flax, hemp, jute, sisal and kenaf are some of the most important natural fibres used in these composite materials, called biocomposites. They are abundant, easy to process, renewable and inexpensive.

* To read the full article further, click here.

 

* This extract is reproduced with the permission of the Mail & Guardian’s Science Voices supplement. It was published in 2014 as part of an endeavour to boost science communication among postgraduate students in South Africa.

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