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A Second Life for Bioplastics
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Natural plastic sounds like a very modern invention - the cutting edge of sustainable living, even. Yet, before World War II most objects in use had a natural origin, such as wood, rubber, and earthenware. Petroleum-based plastics then steadily replaced natural raw materials for an extraordinary number of new products, and most manufactured objects were thus made synthetically. But today natural feedstock is back in vogue, enjoying a second life.
With global warming and sustainability so firmly on the agenda, not to mention ever rising oil prices, many new types of plastics are attracting interest from both consumers and industry. Some are oil-based but biodegradable, others are made from natural and renewable materials since the beginning. Could oil be displaced by biomass as the major feedstock for synthesis? Or is it just a fad?
Harald Kaeb, Chairman of European Bioplastics, says that bioplastics are not just hype. "Twenty years of material development have now passed since the initial days of invention and research. Now their introduction into the first niche markets has been successfully managed, and many experts anticipate that they will enter mass markets in the next few years." Packaging with compostable bioplastics is currently the largest sector, followed by biodegradable films that can be simply ploughed into the fields, where they soon break down into carbon dioxide and water. Other mass market applications could in the future include bulk plastics in automobiles, or parts in electronic devices such as computers, mobile phones and DVDs.
State your terms
Technologists usually limit the use of the term ‘bioplastic' to describe a polymer produced from a biological - thus potential renewable - source [1] . Nevertheless, the term is often applied to biodegradable or compostable plastics in general, also when made from petrochemical feedstock.
One reason for this confusion in terminology is that both features of ‘bioplastics' (i.e. the properties of being biodegradable or renewable) have progressively become more and more appealing. "Renewable raw materials help to improve sustainability and spare oil consumption whilst biodegradation is an effective disposal route for plastic waste," says Mr Kaeb.
Promising materials
Over half of the bioplastics on the market today are made from starch, often extracted from maize (also known as corn). Additives such as sorbitol and glycerine allow the starch to be processed thermo-plastically. By varying the amounts of these additives, the characteristic of the material can be tailored to specific needs. In Europe, the Italian company Novamont dominates the market with its maize-based Mater-Bi film [2], [3] . Mater-Bi can be turned into an enormous range of products, including shopping bags, disposable cups, sheet mulch and even car tyres.
Another type of bioplastic is polylactic acid or polylactide (PLA), which is derived from fermented corn or sugar cane feedstocks. This polymer shares many characteristics with "mass production plastics" such as polyethylene terephthalate or polystyrene, and can also be processed easily on the same equipment as these more conventional plastics. NatureWorks, a subsidiary of Cargill, is the world's largest producer of PLA with a capacity of 140 000 tonnes per annum.
Furthermore, there are polyhydroxyalkanoates (PHAs). They are a group of aliphatic polyesters that can be produced not only by synthetic methods, but also by the bacterial fermentation of sugars or lipids. The fermentation process was developed by ICI Zeneca in the 1980s, and Monsanto produced a genetically modified PHA-producing canola plant in 1994. PHAs have great potential as a versatile plastic, but there are many technological barriers to high-volume production, including its extraction and purification from bacterial media, and its properties during thermoforming. PHAs are used in materials like polyethylene and polypropylene, for films, injection moulding, blow moulding and bottles. Today this biodegradable, bio-based plastic is a sleeping giant, waiting to be awakened by technological advances. A joint venture between Metabolix and ADM in the USA to build a 50 000-tonne PHA production plant could pave the way for a new wave of PHA plastics.
Subdued or substantial growth?
The European consumption of bioplastics doubled between 2001 and 2003 and is now roughly 50 000 tonnes per annum. Yet, despite the progress recorded over the past few years, the market for bioplastics is still modest and may be set for a significant growth, notes Mr Niaounakis.
"Bioplastics have not been taken out of their specialty niche to the mass production market yet. They account for less than 1% of the world annual production of plastics (>100 million tonnes), with almost all of that going to low-grade applications such as food packaging. The slow growth is attributed to the high production costs and the inferior thermo-mechanical, physical and processing properties of bioplastics compared to petrochemical ones. There is still much inventive work to be done, to both save costs and improve properties ".
winner of the European Inventor
of the Year 2007 award.
With her team at Novamont,
she moved patented bioplastics
from laboratory to market lead.
Progress is not easy, and there have been setbacks. Toyota, which set ambitious goals in 2003 for the commercial use of bioplastics, scaled back its commitment [4] . Dow pulled out of a major bioplastic joint venture with the agricultural and industrial company Cargill due to slow sector maturation [5] . BASF's initial investigations on the possibility of using PHAs were disappointing. "The main focus of the bioplastics industry is to develop innovative processing and compounding technologies," says Mr Kaeb. "This work will produce highly competitive materials - sustainably sourced, with cutting-edge properties."
"Meanwhile, worries have arisen that renewable bioplastics too could be not neutral onto the environment," Niaounakis adds. "True, carbon dioxide produced by their decay will not result in a net increase in green-house gases, and so cannot contribute to global warming. But life-cycle assessment studies have shown that cellulose polymers also need more energy and water to produce and result in high environmental impacts than crude oil-based polyolefins [6] . Similar concerns were expressed in a recent UN report on biofuels [7] ."
The need for technological advances is strongly motivated: there are plenty of opportunities for inventors.
From the perspective of patenting
The analysis of patenting activities in bioplastics is not straightforward, says Michael Niaounakis. "Bioplastics fall into a whole host of different technical fields, and it is difficult to get an idea of the big picture." Nevertheless, Niaounakis confirms what a quick look on the supermarket shelves would suggest: packaging, the biggest segment for bioplastics, has been indeed recording dynamic growth.
The number of European patent applications related to bioplastics in the technical fields of packaging and laminates has doubled since the end of the 1990s. It also appears that, despite setbacks, bioplastics are also growing in importance in the automotive industry, whilst continuing to be polymer of choice for medical applications.
The field remains ripe for patentable inventions, and for innovation. "Firstly, there is the whole issue of costs," says Mr Niaounakis. "Companies must develop efficient processes to reduce production expenses. This could be at any stage in the polymer's life cycle, including the production of raw materials, the extraction and purification of monomers, and the end-of-life processing." One particularly intriguing area appears to be the genetic modification of micro-organisms to convert and process renewable feedstock efficiently. Such "microbial factories" could become the standard production method for bioplastic production in the not-too-distant future. "Secondly, innovation is about combining of different technologies without compromising the biodegradability properties," Niaounakis continues, "such as hybrid bioplastics, from the copolymerisation of crude oil- and plant-based monomers, and biocomposites, from the compounding of bioplastics with different additives."
Patenting activities related to bioplastics in packaging and laminates are conspicuous.
(click to enlarge )
May 2007, Bruxelles
- Journalist: Edwin Colyer, ESN
- Expert Opinion: Harald Kaeb at European Bioplastics; Michael Niaounakis, Robert Lejeune, Jean-François Mazet, Laurent Decocker, and Myriam Gerber at the EPO.
- Chart: Henry Lehtiniemi, EPO.
- Photo Portrait: Virginia Ramalho, EPO.
- Research and Co-ordination: Leo Giannotti, EPO.
References
[1] Bioplastics on Wikipedia, http://www.wikipedia.com.
[2] WO9403543
[3] WO9010671
[4] "Plastic promises", Nature, 446, 12 April 2007.
[5] "Dow pulls out of bioplastics due to slow sector maturation", Nature 23, 6 June 2005.
[6] Patel, M.; Bastioli, C.; Marini, L.; Würdinger, E. "Life-cycle assessment of bio-based polymers and natural fibres". Chapter in the encyclopaedia "Biopolymers", Vol. 10, Wiley-VCH, 2003, pp.409-452
[7] Sustainable Bioenergy: A framework for Decision Makers. UN-Energy report, May 2007.