A new bio-plastic -ARBOFORM®, made of 100% renewable raw materials has found application in toys. Researchers at the Fraunhofer Institute for Chemical Technology ICT in Pfinztal and the Fraunhofer spin-off TECNARO GmbH have developed the material which is a liquid wood.
But what exactly is liquid wood? The cellulose industry separates wood into its three main components - lignin, cellulose and hemicellulose. Lignin is not needed in papermaking. When lignin is mixed with fine natural fibers made of wood, hemp or flax and natural additives such as wax, it is possible to produce plastic granulate that can be melted and injection-molded. Though this bio plastic had already found application in other end uses, it has been found unsuitable for toys in this form. This is because, to separate the lignin from the cell fibers, the workers in the cellulose industry add sulfurous substances.
Working closely with Schleich GmbH, the research group has been able to reduce the sulfur content in ARBOFORM by about 90% for use in toys. This is a challenging task because sulfur-free lignins are usually soluble in water - and therefore unsuitable for toys. The scientists have solved this problem with the aid of suitable additives by modifying the bio-plastic in such a way that it survives contact with water and saliva undamaged. After being re-processed, about ten times in all, no change was detected in the material properties of the low-sulfur bio-plastic.