Materials • Processes • Finishes
chemistry department at the university, is investigating how it might make starch-based plastics from the egg shells. Food producers need to pay to dispose of egg shells in
landfill: Leicester-based Just Egg, for example, uses 1.3 million eggs per week, and spends £30,000 a year to send 480 tonnes of shells to landfill.
The project aims to develop a way to convert the egg shells into a range of starch-based plastics, and test the mechanical properties such as strength. The researchers also intend to identify ways to use the egg shells as fillers that could ‘bulk up’ different grades of plastic. Potential applications include ready meal food trays and shop fittings – though the ultimate goal is to produce packaging that protects egg products. The team will also try to extract proteins called
glycosaminoglycans (GAGs), for possible use by the pharmaceutical industry.
Waste lines
Plant waste materials is another potentially fertile source that could be used to make bioplastics. The Oil Palm Biomass Consortium (OPBC), coordinated
by Netherlands-based TU Delft, and the innovation unit of the Malaysian Prime Minister’s office, will look at the use of palm waste as a raw material for the chemical industry. Malaysia is one of the world’s largest exporters of palm oil, but current production processes use only the palm fruit. “The waste of the palm plant, such as the stem, leaves
and the processed palm fruits, can form an important source of biomass for bio-fuels, bio-plastics and other products,” said Luuk van der Wielen, professor of bioseparation technology at TU Delft. “The use of such organic materials as palm waste is becoming much more attractive as a more sustainable source of raw materials for the production of chemicals. By this collaboration Dutch chemical companies can gain access to this resource as well.” But these natural materials are not always used as
Fig. 2. The BioIsoprene tyre, which is derived from sugar, should be a commercial reality in 2013.
The company’s managing director, Pankaj Pancholi, said: “It would be great if the egg shells could be recycled into the plastic packaging that we use for egg products.”
Commercial realities A
number of plastics derived from ‘non food’ sources have already been commercialised – or are well
on their way. ● In 2009, Cereplast began work to make bioplastics from algae, and has now added the material to its Sustainables family of biodegradable resins.
● US start-up company Myriant has devised a process to make both lactic acid and succinic acid from cellulose, though not yet in ‘commercial’ quantities. The main use of lactic acid is as the precursor for polylactic acid (PLA), while succinic acid has already been used to make a ‘green’ plasticiser for PVC, and a new type of bioplastic called PBS.
● Packaging giant Sealed Air has created a joint venture with Ecovative, which has
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created a technique to make protective packaging from mushrooms. The material could replace expanded polystyrene.
● Even carbon dioxide could find itself used as a monomer for plastics production.
Although not specifically plant-derived, there is growing interest in using sequestered carbon dioxide – captured from factories and other sources – as a plastic monomer. One project led by Bayer Material
Science has begun to use carbon dioxide as a feedstock to make polyether polycarbonate polyols (PPPs). These can be further processed to make polyurethanes. The carbon dioxide used in the project comes from RWE Power’s lignite power plant near Cologne. There are other projects too: US-based
Oakbio has just begun to produce a bio plastic that uses carbon dioxide from a cement plant as the raw feedstock. Proprietary microbes convert the gas into plastic in a single step. At the same time, a team of German collaborators has used carbon dioxide (from power plant emissions) to create a plastic called polypropylene carbonate (PPC). This has been blended with PHB (a biodegradable plastic that is quite brittle) to create a formulation with similar properties to ABS – a commonly used engineering plastic – which housewares manufacturer Bosch-Siemens Hausgeraete has used to create a housing for a vacuum cleaner. Other partners in the project include BASF, Munich Technical University and the University of Hamburg. ●
chemical precursors. In some cases, they can be used as ‘fibre providers’, adding reinforcement to conventional polymers. An example is Curran, a cellulose material extracted
from carrot waste by Scottish company Cellucomp. It can be blended with a range of conventional resins – including polyurethane, polyester and epoxy – to create composites with
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