What are Bioplastics?
Bioplastics can be widely defined as plastics made, at least in part, from renewable biological raw materials and/or which contain additives to make them biodegrade quickly. They currently account only for about 0.5 percent of global plastics production: about 1.5 million tonnes of bioplastics in 2012, compared with 280 million tonnes of traditional plastics in 2011. However, some experts predict they could eventually replace 90% of the traditional plastics surrounding us today.
But before getting into the nitty gritty of describing bioplastics, we need to define the basic terminology, which can be confusing and misleading unless properly clarified at the outset.
It is important to distinguish between the terms “bio-based“, “biodegradable” and “compostable“.
“Bio-based” refers to the the “beginning of life” of the product, that is, the origin of what the plastic is made from. Bio-based plastics are made, at least in part, from renewable naturally occurring materials (such as shrimp shells or insect bodies) or more commonly from renewable plant biomass such as corn/maize, wheat, potatoes, soy, tapioca, coconut, sugar cane, wood. This is in contrast to traditional fossil-fuel derived plastics made from carbon sources such as petroleum, natural gas or coal. In bioplastics, the carbon source is biological.
Now “biodegradable” refers to the “end of life” of the product, that is, what happens to the product when disposed of after its useful life. A bioplastic product is considered biodegradable if it breaks down completely in the natural environment through the action of naturally occurring microorganisms such as bacteria, fungi, and algae. Such microorganisms are able to use the elements of the bioplastic, principally the carbon and nitrogen, as food.
And “compostable” also refers to “end of life” and in particular whether or not the bioplastic will biodegrade – i.e., break down naturally and completely – in a composting environment, be it a home composter in your backyard or a large-scale industrial municipal composting facility.
Commercial and municipal composting facilities have set levels of heat, aeration and moisture to maximize the activity of the oxygen-requiring microorganisms breaking down the compost. Composting in a home composter is less controlled and generally it will take much longer for things to break down.
Both of these composting methods are in contrast to a landfill, which is an anaerobic (oxygen-free) environment. In a landfill, bioplastics will not readily break down if not exposed to oxygen. And the bioplastics in a landfill that do break down will cause release of the potent greenhouse gas methane, which is produced by the anaerobic bacteria breaking down the material.
So there are a few key distinctions to make here:
- Not all bio-based plastics are biodegradable or compostable.
- Not all bio-based plastics are completely made from natural renewable materials – some may also in part be composed of traditional synthetic plastic resins.
- Bioplastics that are composed of 100% bio-based material can be expected to biodegrade completely.
- Not all bioplastics are bio-based, some can be fossil-fuel based.
- Not all biodegradable plastics are bio-based, some can be synthetic, but still biodegradable.
- All compostable plastics are biodegradable, but all biodegradable plastics are not necessarily compostable.
Types of Bioplastics
- Starch-based plastics constituting about 50 percent of the bioplastics market, thermoplastic starch, currently represents the most widely used bioplastic. Pure starch possesses the characteristic of being able to absorb humidity, therefore Flexibiliser and plasticiser such as sorbitol and glycerine are added so the starch can also be processed thermo-plastically.
- Cellulose-based plastics Cellulose bioplastics are mainly the cellulose esters, (including cellulose acetate and nitrocellulose) and their derivatives, including celluloid.
- Some aliphatic polyesters: The aliphatic biopolyesters are mainly polyhydroxyalkanoates (PHA), poly-3-hydroxybutyrate (PHB), Polylactic acid (PLA) plastics etc.
- PLA is the most common bioplastic in use today. First, corn or other raw materials are fermented to produce lactic acid, which is then polymerized to make PLA.
- Polylactic acid (PLA): Polylactic acid (PLA) is a transparent plastic produced from cane sugarorglucose. Enzymes are used to break starch in the plants down into glucose, which is fermented and made into lactic acid. This lactic acid is polymerized and converted into a plastic called polylactic acid. These are used in the plastic processing industry for the production of foil, moulds, cups and bottles.
- Poly-3-hydroxybutyrate (PHB): The biopolymer poly-3-hydroxybutyrate (PHB) is a polyester produced by certain bacteria processing glucose, corn starch or wastewater. It produces transparent film at a melting point higher than 130 degrees Celsius, and is biodegradable without residue.
- Polyhydroxyalkanoates(PHA): These are linear polyesters produced in nature by bacterial fermentation of sugar . They are produced by the bacteria to store carbon and energy. In industrial production, the polyester is extracted and purified from the bacteria by optimizing the conditions for the fermentation of sugar. These plastics are being widely used in the medical industry.
- PBAT (short for polybutylene adipate terephthalate) is a biodegradable random copolym
er, specifically a copolyester of adipic acid, 1,4-butanediol and dimet hyl terephthalate. It is generally marketed as a fully biodegradable alternative to low-density polyethylene, having many similar properties including flexibility and resilience, allowing it to be used for many similar uses such as plastic bags and wraps.
- Bio-derived polyethylene: The basic building block of polyethylene is ethylene. This is just one small chemical step from ethanol, which can be produced by fermentation of agricultural feedstock’s such as sugar cane or corn. Bio-derived polyethylene is chemically and physically identical to traditional polyethylene – it does not biodegrade but can be recycled. It can also considerably reduce greenhouse gas emissions. It is used in packaging such as bottles and tubs.
Terminologies mostly used in Bioplastics with their explanation for easy reference.
Occurring without oxygen.
An organization that develops international standards for materials, products, systems, and services used in construction, manufacturing and transportation. The standards for bioplastics compostability are defined by ASTM D6400 and ASTM D6868.
Defined by the 2002 Farm Bill, biobased products are commercial or industrial products (other than food or feed) that are composed in whole, or in significant part, of biological products, renewable agricultural materials (including plant, animal, and marine materials), or forestry materials.
Biodegradable Plastics are plastics that are completely assimilated by the microorganisms present in defined environment as food for their energy. The carbon of the plastic must completely be converted into CO2 during the microbial process.
Organic, non-fossil material that is available on a renewable basis. Biomass includes all biological organisms, dead or alive, and their metabolic by-products, that have not been transformed by geological processes into substances such as coal or petroleum. Examples of biomass are forest and mill residues, agricultural crops and wastes, wood and wood wastes, animal wastes, livestock operation residues, aquatic plants, and municipal and industrial wastes.
(As defined by European Bioplastics e.V.) is a term used to define two different kinds of plastics: a. Plastics based on renewable resources (the focus is the origin of the raw material used) b. Biodegradable and compostable plastics according to EN13432 or similar standards (the focus is the compostability of the final product; biodegradable and compostable plastics can be based on renewable (Biobased) and/or non-renewable (fossil) resources).
Bioplastics may be:
- Based on renewable resources and biodegradable;
- Based on renewable resources but not be biodegradable; and
- Based on fossil resources and biodegradable.
A professional association of key individuals and groups from government, industry and academia, which promotes the use, and recycling of biodegradable polymeric materials (via composting). It provides scientific testing standards and independent review of test results to certify that products will biodegrade in a composting facility.
The total amount of greenhouse gases emitted directly and indirectly to support human activities, usually expressed in equivalent tons of either carbon or carbon dioxide. Carbon footprints are calculated by countries as part of their reporting requirements, as well as by companies, regions, or individuals.
Carbon neutral describes a process that has a negligible impact on total atmospheric CO2 levels. For example, carbon neutrality means that any CO2 released when a plant decomposes or is burnt is offset by an equal amount of CO2 absorbed by the plant through photosynthesis when it is growing.
The most common organic compound on Earth, it is the structural component of the primary cell wall of green plans and many forms of algae. About 33% of all plant matter is cellulose. Also a polymeric molecule with very high molecular weight (biopolymer, monomer is Glucose), industrial production from wood or cotton, to manufacture paper, plastics and fibers.
A soil conditioning material of decomposing organic matter which provides nutrients and enhances soil structure.
Plastics that are biodegradable under ‘composting’ conditions: specified humidity, temperature, microorganisms and timeframe.
A solid waste management technique that uses natural process to convert organic materials to CO2 water and humus through the action of microorganisms.
Term referring to what happens to an item after it has been consumed or used.
The European branch association representing industrial manufacturers, processors and users of bioplastics and biodegradable polymers and their derivative products. Plastic products can provide proof of their compostability by successfully meeting the harmonized European standard, EN 13432 or EN 14995.
The bulk raw material used to create plastic. Traditional plastics use petroleum feedstock that are not renewable. Bioplastics use bio-materials as feedstock, including corn, wheat, tapioca, and potatoes.
Any naturally occurring carbon or hydrocarbon fuel, such as petroleum, coal, and natural gas, formed by the decomposition of prehistoric organisms.
A controversial topic, as much of the feedstock planted for industrial uses is genetically modified. It raises the question of the potential contamination of conventional crops.
A gas in the atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect (phenomenon where the atmosphere traps solar heat radiated back from the earth’s surface), contributing to climate change and the destruction of the ozone layer. In order, the most abundant greenhouse gases in the Earth’s atmosphere are carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons.
Able to effectively absorb moisture in the air.
An examination, like an audit, of the total impact of the product or service’s manufacturing, use, and disposal in terms of material and energy. This includes an analysis and inventory of all parts, materials, and energy, and their impacts in the manufacturing of a product but usually doesn’t include social impacts.
A colorless, explosive greenhouse gas with a global warming potential estimated at 23 times that of carbon dioxide. Released as bacteria decompose organic materials in landfills.
Not able to be consumed and/or broken down by biological organisms. Non-biodegradable substances include most traditional plastics such as polyethylene, polypropylene, polystyrene, etc. and many chemicals used in industry and agriculture.
A petroleum based plastic with metal salt additives that enables the plastic to degrade / fragment when subject to certain environment conditions. This plastic is not consumed by microorganism and would be non-biodegradable.
The largest volume plastic in the world. This plastic came to the fore during the World War II years, first as an underwater cable coating, then as a critical insulating material for such vital military applications as radar cable. Applications for polyethylene are many and varied, including: packaging films; trash, garment, grocery and shopping bags; molded housewares; toys; containers; pipe; drums; gasoline tanks; coatings and many others.
Is linear polyester produced in nature by bacterial fermentation of sugar or lipids. The most common type of PHA is a PHB (polyhydroxybutyrate).
Polylactide or Polylactic Acid (PLA) is a biodegradable, thermoplastic, aliphatic polyester from lactic acid. Lactic acid is made from dextrose by fermentation. Bacterial fermentation is used to produce lactic acid from corn starch, cane sugar or other sources. However, lactic acid cannot be directly polymerized to a useful product, because each polymerization reaction generates one molecule of water, the presence of which degrades the forming polymer chain to the point that only very low molecular weights are observed. Instead, lactic acid is oligomerized and then catalytically dimerized to make the cyclcic lactide monomer. Although dimerization also generates water, it can be separated prior to polymerization. PLA of high molecular weight is produced from the lactide monomer by ring-opening polymerization using a catalyst. This mechanism does not generate additional water, and hence, a wide range of molecular weights are accessible.
Another “workhorse” of the plastics industry, polypropylene is one of the high-volume “commodity” thermoplastics. Polypropylene was developed out of the Nobel award-winning work of Karl Ziegler and Professor Natta in Europe, and came to the United States in 1957. It belongs to the “olefins” family, which also includes the polyethylene, buy it is quite different in its properties. It has a low density, is fairly rigid, has a heat distortion temperature of 150°F to 200°F degrees Fahrenheit (making it suitable for “hot-fill” packaging applications), and excellent chemical resistance and electrical properties. Major applications of commercial PP are packaging, automotive, appliances and carpeting.
The process of reclaiming materials from used products or materials from their manufacturing and using them in the manufacturing of new products. It is different from Reuse, where products are not destroyed and remanufacture but cleaned and repaired to be used again, also known as remanufacturing.
Any material or energy that can be replenished in full without loss or degradation in quality
Natural polymer (carbohydrate) consisting of an amylose and an amylopectin, gained from maize, potatoes, wheat, tapioca etc. When glucose is connected to polymer-chains is definite way the result (product) is called starch. Each molecule is based on 300-12,000 glucose units.