Zero Waste: Biodegradable plastics
Biodegradable plastic bags and packaging aren’t an end solution to replacing non-degradable plastic bags in supermarkets and retails stores for the following reasons: -
They do not decompose in properly managed landfills. -
They support the throwaway mindset and the use of landfills as an acceptable disposal method -
They do not discourage over-use in the first place. Definitions of bioplastics: -
Compostable plastic: A plastic that undergoes biological degradation during the composting process (up to 2-3 months in a windrow) to yield carbon dioxide, water, inorganic compounds and biomass at a rate consistent with other known compostable materials and leaves no visually distinguishable or toxic residues. -
Biodegradable plastic: A degradable plastic in which the degradation must result from the action of naturally occurring microorganisms over a period of time (up to 2-3 years in a landfill). -
Degradable plastic: An oil based plastic containing a chemical additive that undergoes significant change in its chemical structure causing it to break down into smaller particles. The degradation process is triggered only when material is exposed to specific environmental conditions (such as UV, heat and moisture). Residues are not food matter for microorganisms and are not biodegradable or compostable. Examples of bioplastics: - Scion (Rotorua, NZ) has developed a range of commercial biodegradable plastic formulations compounded in NZ, using commercial bioplastics such as poly lactic acid (PLA) and others, which intelligently or programmably biodegrade in soil or other environments. Such products (eg plastic moulding compounds or masterbatches for extrusion or injection moulding etc) are now available on a commercial basis through a NZ manufacturer. Scion develops new materials and formulations for biodegradable plastics and other functional bioplastics by using renewable biobased resources and their process residues as sources of chemical or polymer additives. Such additives are also useful in other polymer products such as adhesives, coatings, foams, or composites and fibre based materials. Scion has extensive experience in testing and formulation of biodegradable plastics and bioplastics.
For more information click here or contact Alan Fernyhough at the Scion. - New Zealand Potato Plate Company, based in Blenheim, makes “100% biodegradable and compostable” disposable packaging, such as plates, from potato starch. Its products are sold through supermarket chains Progressive and Foodstuffs in the South Island. The company is promoting the products as being suitable for all fast food, microwave, and freezer use and says that they have excellent insulation qualities and fully degrade in days after use. All products are made from food-grade raw materials with no preservatives or toxins of any form. The used product is put straight on the compost heap and worm bin or fed to pigs. For more information on biodegradable and compostable food packaging go to www.potatopak.com and www.earthshell.com
- Novamont, Italy manufactures Mater-Bi. Their promotional material says that it is a new generation of bioplastics derived mainly from natural renewable resources, including starch. Minimizing environmental impact it maintains the same characteristics of plastics but is “completely biodegradable within a composting cycle”. www.novamont.com
- The Cooperative Research Centre for International Food Manufacture and Packaging Science (Melbourne) says it has developed “the most advanced biodegradable packaging in the world”, made from cornstarch. It eventually disintegrates when exposed to water and in the long term disappears completely. This product would be suited to some aspects of putrescible collections, food packaging and farming. (Ref: www.theage.com.au)
- Plantic Technologies, Australia, has developed Bioplastic packaging – “biodegradable” food packaging that it says is cheap enough to compete with conventional plastic. The cornstarch–based material has the look, feel and flexibility of conventional plastic and can be used for a range of items, from cellophane to plant pots and medical devices. It biodegrades at 33 degrees Fahrenheit, after exposure to both moisture and microorganisms in the soil. (Ref. Wired, 26/06/02)
Other contacts and resources - ‘Green Plastics: An Introduction to the new science of Biodegradable Plastics, ’E.S. Stevens
- The Institute for Local Self Reliance created the ‘Carbohydrate Economy Clearinghouse’ to provide accessible, up-to-date information spanning all facets of the ‘carbohydrate economy’. (Carbohydrates, the building blocks of plant matter, can be converted into chemicals, energy, textiles, building materials, paper, and many other industrial products. They call this new materials base a ‘carbohydrate economy’.) Go to www.carbohydrateeconomy.org for more details. Go to the search function and type in packaging and here you will find comprehensive information on plant matter-based products, cutting edge companies (and cooperatives) producing them and reports on developments in this rapidly expanding field.
- The International Biodegradable Products Institute (BPI) is a multi-stakeholder association of key individuals and groups from government, industry and academia which promotes the use and recovery of biodegradable polymeric materials. BPI aims to accomplish this goal through education, adoption of scientifically based standards and cooperative activities with other organizations in the USA, Canada, Europe and Japan. Ever since the introduction of ‘biodegradable plastics’ fifteen years ago, confusion and scepticism about claims and product performance has prevailed. This situation stems largely from plastic products that did not biodegrade as expected, yet were able to make claims because no scientifically based test methods and standards existed. However, along with the advancement of technology, standards have been developed. The ‘Compostable Logo’ has been designed for consumers, composters, regulators and others to reduce confusion about bioplastics. It is a recognisable brand (that can be placed on the actual product, packaging materials and sales literature) and builds credibility and recognition for products that meet the American Society for Testing and Materials Standards.Go to www.bpiworld.org for more details.
Other useful websites include:
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