A compostable polymer made from lignocellulosic biomass from non-food crops such as tress could offer a significant advance on polylactic acid (PLA) for use in packaging.

Sugar derivatives are being modified by researchers at Imperial College London, UK, in a series of chemical transformations to create a polymer that unlike PLA is potentially domestically, rather than industrially, degradable, does not rely on food crops and is less energy intensive to manufacture.

Polylactic acid is produced by fermenting lactic acid from corn starch and is used in biomedical applications and the preparation of bioplastic for packaging. ‘The new chemical process is potentially useful because the yields of the transformations are high. The modified sugars can also be copolymerised with lactide to produce a modified PLA which degrades more rapidly,’ states Lead Academic, Dr Charlotte Williams.

The temperature required to prepare the material is ‘reasonable’, while water is not used to prepare the polymer, lowering energy use. Although it is needed to degrade the biomass.

Due to the high functionality of the sugar feedstock increasing the hydrophilicity of the materials, there is strong potential for the oxygen rich, sugar-based polymer to be compostable at home, argues Williams. However, the six-year research programme is still at early stage of development. The degradation rate will heavily depend on water uptake and the speed at which it will degrade cannot as yet be confirmed.

Keith Barnes, Chairman of The Packaging Society, of the Institute of Materials, Minerals and Mining, asserts, ‘While it seems sensible to suggest that the plastic can then be put on a compost heap, not everyone has such a facility or even a garden. So the rest of us put it in a waste bin. There is no confirmation still of what process can be used with this, injection mouldings, film production or otherwise. The principles behind the research are ideal and it could provide a new feedstock, but only time will tell’.

Regulatory compliance will also be needed if applications involving food packaging are to be investigated. The next stage of the research will be processing and testing, assessing manufacturing models, cost effectiveness and measuring energy use via chemical processes, versus that of fermentation. Experts in sustainability are exploring the material’s lifecycle.