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Degradable plastics get chook injection

Hens standing in a line with fine brown feathers

In the United States 2 million tonnes of feathers go to waste annually - but they could be made into 2.6 million tonnes of biodegradable plastic (Source: Kym McLeod/stock.xchng)

Waste not Chicken feathers could be the backbone of the next major plastics revolution, according to a US research team.

Every year in the US, industrial poultry farms produce about 2 million tonnes of feathers, most of which end up as waste. At the same time, the world is facing a growing mound of discarded plastic.

A research team led by Dr Yiqi Yang of the University of Nebraska-Lincoln has now developed a technique whereby chicken feathers can be turned into biodegradable thermoplastics.

They presented their findings, published in the Journal of Agricultural & Food Chemistry, at this week's 241st National Meeting & Exposition of the American Chemical Society.

Yang says others have tried to develop thermoplastics from feathers but that so far none of them perform well when wet.

"A lot of people have tried to use protein materials as the matrix material. They did not use chicken feathers, but soya protein or plant proteins. But the problem is the water stability," he says.

"We believe we're the first to demonstrate that we can make chicken-feather-based thermoplastics stable in water, while still maintaining strong mechanical properties."

Thermoplastics are one of two major groups of plastics, which include nylon, polyethylene, polystyrene and polyvinyl chloride.

They need heat or chemicals to harden from a liquid into a solid shape, can be melted and remoulded, and are used in a wide range of consumer and industrial products.

Aiming to reduce hydrocarbon use

Most are made from hydrocarbons - ingredients obtained from oil or natural gas. Yang says one of the driving ideas behind the research is to reduce the use of hydrocarbons in plastic production. He says that using this biological resource which is presently going to waste makes good environmental sense.

"First of all we wanted to make something that is totally degradable; polyethylene and polypropylene are not," Yang says.

"Secondly it's renewable. So you can have a bio-source of materials instead of using petrol based materials."

Chicken feathers are mainly made of keratin, a resilient protein also found in hair, hoofs, horns and wool. Yang and his team believe keratin could add strength and durability to plastics.

Yang says the team's success lies in the fact that they approached the problem from a different angle.

"What we've tried to do is to turn the feathers themselves into thermoplastic, so it can also be used as the matrix material for composites, instead of using polyethylene or polypropylene."

A chemical called methyl acrylate is added to the keratin, making it undergo polymerisation, the process which makes molecules link into long chains. This creates a film, which Yang's group calls "feather-g-poly(methyl acrylate)" plastic.

Yang says that although there are still petrochemicals involved in the process, they eventually hope to find other 'green' chemicals that could be used.

He says the next step on the way to industrial development is to assess their biodegradability.

How soon we see chicken feather plastics on the market depends on industry becoming interested and investing in the process, Yang says, but he sees a wide range of possible applications for the product.

"Furniture construction, films, fibres or even fast-food containers," Yang says, "if people don't think of feathers when they get their food in it."

Tags: pollution, biology, chemistry, environmental-technology