Materials • Processes • Finishes
4 As the quest for sustainability continues, researchers are finding ever more obscure starting materials from which to make plastics. Lou Reade reports.
4 Comme la recherche de durabilité continue, les chercheurs trouvent de plus en plus de matières de départ ignorées à partir desquelles fabriquer du plastic. Rapport de Lou Reade.
4 Während die Suche nach der Nachhaltigkeit weiter andauert, finden Forscher immer beiläufigere Ausgangsmaterialen, aus denen sich Kunststoffe herstellen lassen. Lou Reade berichtet.
Natural selection points way for bioplastics
P
olymers made from renewable resources like sugar and starch – rather than oil – are on the increase: a recent report from Freedonia estimates that demand for bioplastics will swell
by 30 per cent in the next five years – reaching 1 billion tonnes. This is only a tiny fraction – around 1 per cent
– of global plastics production, but it shows a new direction for materials research. Major end users such as Ford, Procter & Gamble and Coca-Cola are all pouring large fortunes into the search for bio-based materials, which will help them live up to their sustainability commitments. Until now, commercial production of bioplastics
has been limited to a few starting materials: polylactic acid (PLA) is a biodegradable polymer derived from corn; others, such as PHA and PHB, are made from starch; there has also been a recent surge in polyamides made from castor oil, and polyethylene derived from ‘bio ethanol’ (which in turn comes from sugar cane).
But the real challenge for the future is to avoid ‘food’ crops and use either non-food crops - or food waste – so as not to avoid inflating food prices. Researchers have already uncovered a range of
surprising - and occasionally bizarre - raw materials that could be used as polymer precursors. Instead of sugar and starch, think eggshells, mushroom compost and meat proteins. Other potential sources include algae, cellulose and food industry waste such as shells and husks.
Protein supplement
Researchers in New Zealand have developed a way of turning blood meal – a waste product from meat processing – into a bioplastic. The technology, developed from research led by
Waikato University senior lecturer Johan Verbeek and since spun out into a commercial company called Novatein, which will attempt to take the idea to market. It expects to have developed a commercial product within the next few years. The plastic made in the process has similar
mechanical properties to low density polyethylene (LDPE), and is made using a ‘scalable process’. Around 1.5kg of bioplastic can be made from
1kg of blood meal. New Zealand’s meat industry produces around 80,000 tonnes/year of bovine blood.
Similar research at Clemson University in
the US has also identified the potential to make plastic from blood. In a paper presented at last year’s ‘Antec’ plastics technical conference in the US, researchers Sam Lukubira and Amod Ogale, of the department of chemical and biomolecular engineering, told delegates how they had used meat- and bone-meal (MBM) to produce bioplastic sheets, for potential use in sheets for geo-structural applications. When the relative humidity of the MBM
powder was above 55 per cent, excessive denaturation occurred, producing a dark, glue- like material. Glycerol was used as a plasticiser (in quantities of around 30 per cent by weight), and the pressed sheets were tested for mechanical properties. Those made with finely ground particles (less than 250 microns) were twice as strong as those made from larger particles.
Walking on eggshells
Fig. 1. Siemens - vacuum cleaner part. This vacuum cleaner housing is made from a new blend of material, derived in part from CO2
from power plant emissions.
Scientists at the University of Leicester are looking to create new types of plastics from egg shells. A research team is led by Andy Abbott,
professor of physical chemistry and head of the
www.engineerlive.com 25
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