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Liquid Wood from pulp based lignin : a strong, non-toxic alternative to petro-based plastics |
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Plastics, though one of the great innovations of the 20th century, have a number of issues. It is also based on petroleum, a non-renewable resource that will soon be harder to come by, leads to increased CO2 levels causing global warming and depletion of oil reserves. Increases in the price of crude oil leads to parallel rises in the price of plastics. A new invention - liquid wood could do away with these long-standing concerns and complement plastics.
Scientists from Fraunhofer Institute for Chemical Technology (ICT), Germany have developed a substance that could replace plastic: Arboform -- basically, liquid wood. It is derived from wood pulp-based lignin and can be mixed with a number of other materials to create a strong, non-toxic alternative to petroleum-based plastics.
Arboform is not made from felling of trees but it is manufactured from the waste products of the paper industry. The paper industry separates out the three components of wood-lignin, cellulose and hemicellulose. Lignin is not used in the manufacture of paper as it gives paper a brownish hue. Often it is used in low quality newsprint but more often than not it is separated out with a sulfite or sulfate based pulping process prior to production of high quality paper. Lignin is the part of the wood in trees that lends support. The scientists mix that lignin with fine natural fibers made of wood, hemp or flax and natural additives such as wax. From this plastic granulate that can be melted and injection-moulded were produced. The final product can resemble highly polished wood or have a more matted finish and look like the plastic used in most household items. The team has been able to reduce the sulphur content in Arborform by about 90%, making it much safer for use in everyday items.
To achieve low sulfur content and water proofing capabilities, the thermoplastic was subjected to high pressure hydrolysis. This eco-friendly alternative to plastic is produced from lignin which is abundant in renewable resource, non-toxic and biodegradable. It can be manufactured on a mass scale as well as molded into any shape or form. Experiments reveal that on heating or cooling it several times, it can still be remolded, reshaped and recycled. It can be disposed off in the same manner as wood-either through incineration or decomposition. Hundred million tonnes of global petroleum delivers insurmountable amounts of carbon dioxide into the atmosphere on combustion.
Arboform when used as an alternative bioplastic, the carbon dioxide (CO2) entering the atmosphere on incineration remains unchanged. It releases only that amount of carbon dioxide that the plant had originally fixed from the environment during its growth. Thus, the carbon cycle is closed and not disrupted. Liquid wood does not require any elaborate process to change its chemical composition before disposal. In fact it can even be discarded off like wood.
Arboform has better thermal and mechanical properties than both, wood and plastic put together. Wood tends to split at right angles when subjected to strain but not Arboform. It is a biodegradable thermoplastic engineering material of superior quality and strength that will meet the technological demands replacing the indomitable market giant-plastic. |
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