Bioplastic

Bioplastics are a form of plastics derived from plant sources such as hemp oil, soy bean oil and corn starch, or from a microbial source, rather than traditional plastics which are derived from petroleum. Bioplastics are mainly composed by a matrix (resin) and a reinforcement of natural fibers (usually derived from plants or cellulose). With wide-ranging uses from environment-friendly biodegradable composites to biomedical composites for drug/gene delivery, tissue engineering applications and cosmetic orthodontics. They often mimic the structures of the living materials involved in the process in addition to the strengthening properties of the matrix that was used but still providing biocompatibility, e.g in creating scaffolds in bone tissue engineering.

Bioplastics are characterised by the fact that:

• the petrochemical resin is replaced by a vegetable or animal resin, and/or
• the bolsters (glass or carbon fibre or talc) are replaced by natural fibre (wood fibres, hemp, flax, sisal, jute...)

Those markets are significantly rising, mainly because of the increase in oil price, and recycling and environment necessities.

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Bioplastics and biodegradation

Terminology used in the bioplastics sector is quite confusing. Most in the industry use the term bioplastic to mean a plastic produced from a biological - and hence renewable and potentially sustainable - source. Cellulose film, for instance, is one of the oldest plastics. It is, and has always has been, made from wood cellulose and is fully biodegradable in its natural form. The wood it is made from can be sourced from commercially managed forestry. Innovia ^[1] is one of the major producers of cellulose film - some of which it markets as biodegradable.

Many bioplastics are biodegradable, meaning they can be degraded by microbes under suitable conditions. Some bioplastics will biodegrade in the relatively cool conditions of a home compost heap. Most will only degrade in the hotter and more tightly controlled conditions of commercial composting units.

While many bioplastics are biodegradable, some are not - referred to as durable. Even some petrochemical-based plastics are biodegradable. The Ecoflex ^[2] range of biodegradable plastics manufactured by BASF of Germany is an example of this type. This material is used as an additive to improve the performance of many commercial bioplastics.

There is an internationally agreed standard that defines how quickly and to what extent a biodegradable plastic must be degraded under commercial composting conditions - EN13432. This is published by the International Organisation for Standardization ISO ^[3] and is recognised in many countries, including all of Europe, Japan and the US. However, it is designed only for the aggressive conditions of commercial composting units. There is no standard applicable to home composting conditions.

The term biodegradable plastic is often also used by producers of specially modified petrochemical-based plastics which appear to biodegrade. A little explanation is needed here. Traditional plastics such as polyethylene are degraded by ultra-violet light and oxygen. To stop this process, and to make the plastics usable, manufacturers add stabilisation chemicals. By adding a controlled amount of degradation initiator to the plastic it is possible to achieve a controlled disintegration process driven by the ultra-violet light in sunlight or by atmoshpheric oxygen. The North American company EPI ^[4] is a leading player in this type of additive technology.

This degradation process is highly effective. However, this type of plastic is best referred to as "degradable plastic" or "oxy-degradable plastic" because the process is not initiated by microbial action. Some degradable plastics manufacturers argue that, once a certain level of degradation of the plastic has been achieved, the degraded residue will be attacked by microbes. However, this route has yet to be proven. In any case, these degradable materials do not meet the requirements of the EN13432 commercial composting standard.

Environmental Impacts

The production and use of bioplastics is generally regarded as a more sustainable activity when compared with plastic production from petroleum, because it relies less on fossil fuel as a carbon source and also introduces less, net-new greenhouse emissions if it biodegrades.^{[citation needed]} However, manufacturing of bioplastic materials is often still reliant upon petroleum as an energy and materials source. This comes in the form of energy required to power farm machinery and irrigate growing crops, to produce fertilisers and pesticides, to transport crops and crop products to processing plants, to process raw materials, and ultimately to produce the bioplastic.

Other market issues

Italian bioplastic manufacturer Novamont ^[5] states in its own environmental audit ^[6] that producing one kilogram of its starch-based product uses 500g of petroleum and consumes almost 80% of the energy required to produce a traditional polyethylene polymer.Environmental data from NatureWorks^[7], the only commercial manufacturer of PLA (polylacticacid) bioplastic, says that making its plastic material delivers a fossil fuel saving of between 25 and 68 per cent compared with polyethylene, in part due to its purchasing of [renewable energy] certificates for its manufacturing plant.

A detailed study ^[8] examining the process of manufacturing a number of common packaging items in several traditional plastics and polylactic acid carried out by US-group ^[9] and published by the Athena Institute ^[10] shows the bioplastic to be less environmentally damaging for some products, but more environmentally damaging for others. The authors' key finding is that the use of bioplastics cannot be assumed to be environmentally beneficial, but has to be determined through case by case analysis. With the exception of cellulose, most bioplastic technology is relatively new and is currently not as cost competitive with petroleum-based plastics. And because many bioplastics are reliant on fossil fuel derived energy for their manufacturing, even with today's rising oil prices^[11], that gap is not closing very fast.

Many bioplastics also lack the performance and ease of processing of traditional materials albeit materials such as Bioplast from Stanelco ^[12] have closed this performance gap. Polylactic acid plastic is being used by a handful of small companies for water bottles. But shelf life is limited because the plastic is permeable to water - the bottles lose their contents and slowly deform. However, bioplastics are seeing some use in Europe, where they account for 60% of the biodegradable materials market. The most common end use market is for packaging materials. Japan has also been a pioneer in bioplastics, incorporating them into electronics and automobiles.

While production of most bioplastics results in reduced carbon dioxide emissions compared to traditional alternatives, there are some real concerns that the creation of a global bio-based economy could contribute to an accelerated rate of deforestation if not managed effectively. There are associated concerns over the impact on water supply and soil erosion.

There are also fears that bioplastics will damage existing recycling projects. Packaging such as HDPE milk bottles and PET water and soft drinks bottles is easily identified and hence setting up a recycling infrastructure has been quite successful in many parts of the world. Polylactic acid and PET do not mix - as bottles made from polylactic acid cannot be distinguished from PET bottles by the consumer there is a risk that recycled PET could be rendered unusable. This could be overcome by ensuring distinctive bottle types or by investing in suitable sorting technology. However, the first route is unreliable and the second costly.

Genetic modification (GM) is also a challenge for the bioplastics industry. None of the currently available bioplastics - which can be considered first generation products - require the use of GM crops. However, it is not possible to ensure corn used to make bioplastic in North America is GM-free.

European consumers are hostile to any products that are linked to the GM industry. As a result, some UK retailers such as Sainsbury's ^[13] will not use bioplastic manufactured in the US, such as Natureworks polylactic acid. There is currently no commercial European source of polylactic acid bioplastic.

There is also concern that the route from corn to bioplastics is not the most efficient. Looking further ahead, some of the second generation bioplastics manufacturing technologies under development employ the "plant factory" model, using GM versions of plants such as switchgrass and sugarcane to maximise yield. The US company Metabolix ^[14] is a pioneer in this second generation technology. However, a change in consumer perception of GM technology in Europe will be required for these to be widely accepted.

Market situation

These days plastics are predominantly made from crude oil. However, the increasing hunger for energy worldwide and also political instability in the large oil exporting countries have led to a dramatic increase in the price of oil in recent years. A consistently low oil price, as was seen throughout the 90s, is not very likely in the future. In this context, renewable resources are becoming a more viable and promising alternative for the plastics industry. However, as energy is used in the growing, harvesting and conversion of agricultural crops to bioplastics immunity to rising oil prices is sometimes overestimated.

Because of the fragmentation in the market it is difficult to estimate the total market size for bioplastics, but estimates by SRI Consulting ^[15] put global consumption in 2006 at around 85,000 tonnes. In contrast, global consumption of all flexible packaging is estimated at around 12.3 million tonnes ^[16].

COPA (Committee of Agricultural Organisation in the European Union) and COGEGA (General Committee for the Agricultural Cooperation in the European Union) have made an assessment of the potential of bioplastics in different sectors of the European economy:

Catering products: 450.000 t/a Organic waste bags: 100.000 t/a Biodegradable mulch foils: 130.000 t/a Biodegradable foils for diapers 80.000 t/a Diapers, 100% biodegradable: 240.000 t/a Foil packaging: 400.000 t/a Vegetable packaging: 400.000 t/a Tyre components: 200.000 t/a

Total 2.000.000 t/a

Certification

Adding the prefix "bio-", misrepresenting a plastic compound as biodegradable, or confusing product labeling has become commonplace lately. Several certification schemes have therefore been set up based on the EN 13 432 industrial norm and the French NF U52001 norm, products made out any raw plastic material pretending to be biodegradable, are tested as to their true and biodegradability and compostability. Consumer products and packaging which passed the tests prescribed in the testing protocol laid down in these norms, may carry a special label. So far starch based plastics, PLA based plastics and certain aliphatic-aromatic co-polyester compounds such as succinates and adipates, have obtained these certificates. Additivated plastics sold as fotodegradable, oxobiodegradable have not yet received these certificates and will probably not be eligible as the additives generally contain heavy metals such as cobalt and cannot show a biodegradation whereby over 90% of the plastic mass is converted into biomass and subsequently into carbon dioxide and water. Due to their photo- or oxo degradation, these additivated plastics are not suitable for recycling and can only be properly disposed of by incineration or landfill.

Applications

Packaging

Because of their biological biodegradability, the use of bioplastics is especially popular in the packaging sector. The use of bioplastics for shopping bags is already very common. After their initial use they can be reused as bags for organic waste and then be composted. Trays and containers for fruit, vegetables, eggs and meat, bottles for soft drinks and dairy products and blister foils for fruit and vegetables are also already widely manufactured from bioplastics.

Catering Products

Catering products belong to the group of perishable plastics. Disposable crockery and cutlery, as well as pots and bowls, pack foils for hamburgers and straws are being dumped after a single use, together with food-leftovers, forming huge amounts of waste, particularly at big events. The use of bioplastics offers significant advantages not only in an ecological sense but also in an economical sense.

Non Packaging

Applications outside packaging include mobile phone casings (NEC), carpet fibres (Dupont Sorona), and car interiors (Mazda). The French company, Arkema, produces a grade of bioplastic called Rilsan, which is being used in fuel line and plastic pipe applications.

In these areas, the goal is obviously not biodegradability, but to create items from sustainable resources.

Plastic Types

Starch based plastics

Constituting about 50 percent of the bioplastics market, thermoplastic starch, such as Plastarch Material, currently represents the most important and widely used bioplastic. Pure starch possesses the characteristic of being able to absorb humidity and is thus being used for the production of drug capsules in the pharmaceutical sector. Flexibiliser and plasticiser such as sorbitol and glycerine are added so that starch can also be processed thermo-plastically. By varying the amounts of these additives, the characteristic of the material can be tailored to specific needs (also called "thermo-plastical starch").

Polylactide acid (PLA) plastics

Polylactide acid (PLA) is a transparent plastic made from natural resources. It not only resembles conventional petrochemical mass plastics (like PE or PP) in its characteristics, but it can also be processed easily on standard equipment that already exists for the production of conventional plastics. PLA and PLA-Blends generally come in the form of granulates with various properties and are used in the plastic processing industry for the production of foil, moulds, tins, cups, bottles and other packaging.

Poly-3-hydroxybutyrate (PHB)

The biopolymer poly-3-hydroxybutyrate (PHB) is a polyester produced from renewable raw materials. Its characteristics are similar to those of the petrochemical-produced plastic polypropylene. Interest in PHB is currently very high. Companies worldwide are aiming to either begin production of PHB or to expand their current production capacity. Some estimate that this could result in a price reduction to fewer than 5 Euros per kilogram. However, that is still four times the market price of polyethylene at February 2007. The South American sugar industry, for example, has decided to expand PHB production to an industrial scale. PHB is distinguished primarily by its physical characteristics. It produces transparent film at a melting point higher than 130 degrees Celsius, and is biodegradable without residue.

Polyamide 11 (PA 11)

PA 11 or Nylon 11 is a biopolymer derived from vegetable oil. It is also known under the tradename Rilsan®. PA 11 belongs to the technical polymers family and is not biodegradable. Its properties are similar than PA 12 although emissions of greenhouse gases and consumption of non-renewable resources are reduced during its production. Its thermal resistance is also superior than PA 12. It is used in high performance applications as automotive fuel lines, pneumatic airbrake tubing, electrical anti-termite cable sheathing, oil & gas flexible pipes & control fluid umbilicals, sports shoes, electronic device components, catheters, etc.

Developments

• In the early 1950s, Amylomaize (>50% starch content corn) was successfully bred and commercial bioplastics applications started to be explored.
• In 2004, NEC developed a flame retardant plastic, polylactic acid, without using toxic chemicals such as halogens and phosphorus compounds [1].
• In 2005, Fujitsu became one of the first technology company to make personal computer cases from bioplastics, which are featured in their FMV-BIBLO NB80K line.
• In 2007 Braskem of Brazil announced it had developed a route to manufacture high density polyethylene (HDPE) using ethylene derived from sugar cane.

References