Biopolymers: market potential and challenging research

(Published on March – April 2008 – JEC Magazine #39)

ANTONIO CASALE, TECHNICAL DIRECTOR PROPLAST

Consumers, end users, processors, and manufacturers are all increasingly interested in biopolymers. This is due both to concerns about limited petrochemical resources accompanied by a potential surge in oil prices, and to heightened awareness of ecological problems. According to a recent report, there are currently 26 commercial producers of biopolymers and some 60 companies involved in R&D in this field.

There is still confusion around the definition of biopolymers, as definitions can vary according to the source. As a result, things like statistical data, market prospects and even political initiatives could be subjected to misunderstanding. According to the European Bioplastics Association, bioplastics are either biodegradable polymers with approved biodegradability (EN 13432) from renewable and petrochemical resources, or biobased polymers (polymers from renewable raw materials) that may or may not be biodegradable. According to other sources, only biobased polymers should be classified as bioplastics. Standards for biodegradability and compostability encompass other important concepts.

For example, EN 13432 establishes that biodegradability shall be determined for each relevant organic component accounting for more than 1% of a product’s dry weight; the total quantity of non-relevant organic components should not exceed 5%. This means that biodegradable additives and fillers must be used. Accredited institutes around the world can certify and label the biodegradability of plastics. The same concept is also present in the definition of compostability; the standard also defines not only the level of degradation but also the permissible level of disintegration (after 12 weeks, no more than 10% of the original dry-weight material should be found in the >2 mm fraction of the compost). For soil improvers, the law sets a maximum permissible plastic-fragment content. All this could strongly influence the development of bioplastics, particularly in the case of thick-walled parts (a few some millimetres), typical of durable or industrial goods.

The biopolymer market

Global polymer production capacity is estimated to reach 766,000 metric tons (MT) by 2009 and 1.5 million MT by 2011 (Figure 1). The 2nd European Bioplastics Conference forecasted significant growth for the biobased/nonbiodegradable polymer share. Such growth would push that share up to nearly 40% of total capacity by 2011, compared to about 12% today. Market demand for biopolymers is strongly influenced by factors such as price competitiveness, the potential growth of “fitfor- use” applications, laws and regulations, and the optimization of commercial composting processes. It is interesting to note that, according to a recent report prepared by the Utrecht University and the Fraunhofer Institute for the European Commission’s Institute for Prospective Technological Studies (IPTS), the technical substitution potential of biopolymers is estimated at 33% of total polymer production (about 15 million MT in the EU). According to the European Bioplastics Association, the current technical substitution potential could be as high as 5-10% of plastic consumption, and much more in the long run. The report also provides a detailed analysis of how the biopolymer market could develop in Europe, with three different scenarios: one with supporting policies and measures (P&M), one without P&M, and one with high economic growth. European Bioplastics’ future market potential perspective is in line with the above evaluation (Figure 2).

The huge gap between technical substitution potential and market research results raises the question of whether or not biopolymers will move from niche to mass market. To answer this, a number of critical points need to be taken into account, including cost, raw material availability (agricultural land and biomass), potential industrial and structural application development (short, medium, long term), the ageing and durability of thick-walled moulded parts, and end-of-life issues, i.e. the biodegradability and/or compostability of thick-walled moulded parts.

Cost

Cost is a significant issue for biopolymer development. According to the European Bioplastics Association, biopolymer prices are 80% lower than they were ten years ago, but they are still high at an estimated 1.3-4 euros/kg. In attempts to over come the cost problems, chemical companies (DuPont, Novamont, Metabolix, Rohm and Haas, to take some recent examples) are making agreements or joint ventures with agricultural companies to produce biomonomers or biopolymers (biorefinery) and conducting research in attempts to improve production processes and overcome the cost problem.

Raw material availability

It is well known that only a small percentage of crude oil is used for plastic production. However, the availability of raw materials for biopolymers is closely linked to biofuel production. For example, to replace a mere 10% of the fossil fuels used for transportation, the USA would need to use 43% of its total agricultural land and the EU, 38%. Many countries have set biofuel consumption targets. The EU plans to replace 5.75% of fossil fuels with biofuels by 2010. According to a study published by the European Community, the EU has changed its policy of economic support for agriculture, and soon 25% of Europe’s agricultural land will be taken out of food production. Biopolymer development could constitute a significant source of revenue for the agricultural sector. It is estimated that about 20 million hectares are currently available in Europe for non-food production. Based on a an average yield of about 2-2.5 tons of biopolymers/hectare, that available land could be enough to produce 40-50 million tons of biopolymers a year (i.e. 17-20% of total annual plastic production worldwide). Using biomass as a renewable raw material source could solve the problem for both biofuels and biopolymers, as biomass is available in very large quantities (Figure 3). Unfortunately, technologies that make full use of these materials have not yet been fully developed.

Application development

A major research effort is required to develop formulations that will allow tailoring biopolymers for specific applications. Customized compound development has been the main strong point for plastics expansion. One specific line of development concerns natural-fibrereinforced biocomposites, for which bioadditives and biofillers also need to be developed. Some compounders have recently put specific master batches for PLA on the market. Developing biocomposites would be essential, because bioplastics alone are mediocre structural materials. As with petropolymers, adding fibre reinforcement improves structural and thermal properties (Table 1). One wellknown example of an injection-moulded part is the cellphone case recently developed by Nokia and Unitika. Before natural fibres can be used extensively in moulded parts, however, a lot more research is needed to improve wettability and adhesion through suitable surface changes, and to overcome problems such as high batch-to-batch variability, powder formation, fibre thermodegradation, and yellowing during compounding and processing. The compounds also absorb moisture very fast, so they need to be dried carefully before processing. Using natural fibres in mat form helps to overcome the above problems. Industrial applications use thermosetting, polyurethane and epoxy resins as matrices. To further market development, research is also required in areas like the processability of biopolymers, specifically with respect to biopolymer sensitivity to moisture and temperature and the optimization of processing lines and finishing processes such as bonding, welding, coating, painting, metallizing, laser marking, mechanical assembly, and more.

Ageing and durability

Using biopolymers in the production of durable goods or structural applications (transportation, electrical/electronic appliances, etc.) requires an in-depth study of their indoor and outdoor ageing and durability properties, for which it is still difficult to find relevant data. Many companies are reluctant to develop durable goods using biodegradable polymers due to fears that such products could have a limited service life.

End-of-life (EOL) issues

Another major area of research concerns EOL issues around moulded parts including:

• recyclability and compostability; due to the low volume of biopolymers and because conventional recycling facilities are not designed to accommodate bioplastics, there is a short-term risk of contamination of such plants. For the medium term, dedicated plants will be required;
• biodegradability/compostability of the thick-walled parts only a few millimetres thick that are typical of injection moulded goods; as already mentionned the problem is the compostability of a “millimetres thick” part in comparison to “micron thick” film. This will require changes to the composting lines, such as including a part-milling step. It should be underlined that composting standards set specific limits in terms of time, size and plastic content. Current data and feedback are based mainly on film and other very thin applications.

Conclusion

Biopolymers are a growing and promising field. A vast number of biopolymers have been synthesized and developed, offering a wide range of properties. Many large companies are taking advantage of their experience in plastics to enter the field. Biopolymers have the technical potential to replace engineering plastics, and could be a major new line of development for the plastic sector. Significant sales growth would depend on their expansion in consumer-goods and engineering applications. To achieve this, additional research into customer requirements is needed, with a focus on developing formulations that can meet the specifications for a wide range of applications, biopolymer ageing and weathering, processability and finishing techniques, and compostability/degradability.