Release Date: 21 January 2009
Release ID: 3376
Most plastics are based on petroleum, but researchers from the Fraunhofer Institute have now optimised a bio-plastic that consists of one hundred per cent renewable raw materials. The new material is even suitable for moulding products such as Nativity figurines.
Most plastics are <a href="http://www.engineerlive.com">based</a> on petroleum, but researchers from the Fraunhofer Institute have now optimised a bio-plastic that consists of one hundred per cent renewable raw materials. The new material is even suitable for moulding products such as Nativity figurines.
Toys have to put up with a lot of rough treatment: They are sucked by small children, bitten with milk teeth, dragged along behind toy cars, and every now and then they have to survive a rainy night outdoors. Whatever happens, it is vital that the material does not release any softeners or heavy metals that could endanger children.
According to the researchers, toys can be made of 'liquid wood' in future. The advantage is that this bio-plastic, known as Arboform, is made of one hundred per cent renewable raw materials and is therefore not reliant on petroleum. Researchers at the Fraunhofer Institute for Chemical Technology (ICT) in Pfinztal and the Fraunhofer spin-off Tecnaro GmbH have developed the material.
ICT team leader Emilia Regina Inone-Kauffmann explains what 'liquid wood' is: "The cellulose industry separates wood into its three main components – lignin, cellulose and hemicellulose. However, the lignin is not needed in papermaking. Our colleagues at Tecnaro mix lignin with fine natural fibres made of wood, hemp or flax and natural additives such as wax. From this, they produce plastic granulate that can be melted and injection-moulded."
Car parts and urns made of this bio-plastic already exist, but it is not suitable for toys in this form; to separate the lignin from the cell fibres, the workers in the cellulose industry add sulphurous substances. However, children's toys should not contain sulphur because, for one reason, it can smell very unpleasant.
Tecnaro's managing director Helmut Nägele says: "We were able to reduce the sulphur content in Arboform by about 90 per cent, and produced Nativity figurines in co-operation with Schleich GmbH. Other products are now at the planning stage." This is a challenging task: sulphur-free lignins are usually soluble in water, and are therefore unsuitable for toys. On no account must they dissolve if they are left out in the rain or if children suck them. With the aid of suitable additives, the Tecnaro scientists were able to modify the bio-plastic in such a way that it survives contact with water and saliva undamaged.
Inone-Kauffmann comments on the recyclability of the bio-plastic: "We produced components, broke them up into small pieces, and re-processed the broken pieces – ten times in all. We did not detect any change in the material properties of the low-sulphur bio-plastic, so that means it can be recycled."
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