Bio-plastics harness the natural structures found in crops or trees, such as slightly modified forms of the chains of sugars in starch or cellulose, that share the ability to be easily reshaped that has made conventional oil based plastics so useful. Bio-materials scientists are also constantly tweaking these natural structures to try and better replicate the durability and flexibility of conventional plastics.
Global business is now turning to bio-plastics for an increasing number of applications, as consumers and governments demand cleaner alternatives to petroleum based technologies and their reckless production of the greenhouse gas CO2.
Worldwide players, such as DuPont and Toyota Motor Corp, are making vast investments in new technologies and processing plants with the hope of cornering a multi-billion pound industry.
The "BC" at Bangor University in North Wales has 18-years experience of working with large companies and Non-Governmental Organisations (NGOs) to find sustainable and viable bio-based alternatives to man-made materials.
BC director Paul Fowler points out that “practically anything that you can find as polyethene you can find as a bio-plastic. You are talking about a whole range of everyday products - cups, combs and wrappers, everything you can think of is out there. There are inroads being made all the time - on the one hand there is research into trying to get biological alternatives to replicate the properties of conventional plastics and on the other hand people are looking at the natural properties of these plants and trying to find an application for them. Most of the manufacture is happening in the US and continental Europe. The UK is a producer of wheat starch and biotimber but the only major bioplastic producer is Innovia Films in Cumbria, which produces cellulose films.”
Innovia Films has an annual turnover of £400m, employing 1,200 people worldwide and producing more than 120,000 tonnes of film – used in packaging to protect food. Japan is also forging ahead, from the leading role in bioplastic production played by Toyota to its recent passing of a triumvirate of laws pushing forward environmental initiatives.
In South Korea too there is a rapid drive to replace conventional plastic packaging with polylactic acid bio-plastics.
Fowler says bio-plastics also offer an opportunity to get a double return for the energy used in their manufacture – first as a useful item and secondly as a fuel source. “My view is that we should burn them at the end of their life to recover energy, which could be then used to produce new materials,” he said. “In the first instance you have a valuable resource can use, be it as packaging or a shopping bag, and then you are also getting some energy back at the end of it. The biggest advantage of such bio-materials is the reduction of CO2 emissions in their production over petrochemical-based plastics.”
He also suggests that burning bio-plastics would also avoid the problems caused by them breaking down and producing methane, which is 25-times more potent as a greenhouse gas than CO2.
The BC is currently looking at developing naturally-derived alternatives to phthalates, which are plasticisers added to PVCs to make them more flexible in products such as electrical cable flex. It follows concerns that phthalates are metabolised in the body into substances that can mimic the body's own hormones, including those concerned with fertility. The centre is also developing bio-resins, natural alternatives to synthetic resins such as phenol and formaldehyde.
What types of bioplastic are there?
The common types of bio-plastics are based on cellulose, starch, polylactic acid (PLA), poly-3-hydroxybutyrate (PHB), and polyamide 11 (PA11). Cellulose-based plastics are usually produced from wood pulp and used to make film-based products such as wrappers and to seal in freshness in ready-made meals.
Thermoplastic starch is the most important and widely used bioplastic, accounting for about 50pc of the bio-plastics market. Pure starch’s ability to absorb humidity has led to it being widely used for the production of drug capsules in the pharmaceutical sector. Plasticisers, such as sorbitol and glycerine are added to make it more flexible and produce a range of different characteristics. It is commmonly derived from crops such as potatoes or maize.