Saturday, September 26, 2009

Bioplastics an alternative for plastic bags

Keeping in view the perilous relation with atmospheric pollution the Govt of J&K has taken a very wise step to stop manufacturing degradable plastic bags in the State. So there was a pertinent need to develop its better alternative. The Govt has already undertaken a sound step in this direction in Kashmir by getting a plant there to manufacture bioplastic bags i.e biodegradable bags which are able to decay naturally in a way that is not harmful in any way. Bioplastics (also called organic plastics) are a form of plastics derived from renewable biomass sources, such as vegetable oil, corn starch, pea starch or microbiota, rather than fossil fuel plastics which are derived from petroleum.

The terminology used in the bioplastics sector is sometimes misleading. Mostly the industry uses the term bioplastic to mean a plastic produced from a biological source. One of the oldest plastics, cellulose film, is made from wood cellulose. All (bio-and petroleum -based) plastics are technically biodegradable, meaning they can be degraded by microbes under suitable conditions. However many degrade at such slow rates as to be considered non-biodegradable. Non-biodegradable bioplastics are referred to as durable. The degree of biodegradation varies with temperature, polymer stability, and available oxygen content. Consequently, most bioplastics will only degrade in the tightly controlled conditions of industrial composting units.

The term ‘‘biodegradable plastic’’ is often also used by producers of specially modified petrochemical-based plastics which appear to biodegrade. Traditional plastics such as polyethylene are degraded by ultra-violet (UV) light and oxygen. To prevent this process manufacturers add stabilising chemicals. However with the addition of a degradation initiator to the plastic, it is possible to achieve a controlled UV/oxidation disintegration process. This type of plastic may be referred to as degradable plastic or oxy-degradable plastic or photodegradable plastic because the process is not initiated by microbial action.

The production and use of bioplastics is generally regarded as a more sustainable activity when compared with plastic production from petroleum (petroplastic), because it relies less on fossil fuel as a carbon source and also introduces fewer, net-new greenhouse emissions if it biodegrades. They significantly reduce hazardous waste caused by oil-derived plastics, which remain solid for hundreds of years, and open a new era in packing technology and industry.

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, although renewable energy can be used to obtain petroleum independence. Other studies showed that bioplastics represent a 42% reduction in carbon footprint. On the other hand, bioplastic can be made from agricultural byproducts and also from used plastic bottles and other containers using microorganisms.

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.

Polylactic acid (PLA) plastics
Polylactic acid (PLA) is a transparent plastic produced from cane sugar or glucose. 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 by certain bacteria processing glucose or starch.

Polyamide 11 (PA 11)
PA 11 is a biopolymer derived from natural oil. It is also known under the tradename Rilsan B commercialized by Arkema. PA 11 belongs to the technical polymers family and is not biodegradable.

Bio- derived polyethylene
The basic building block (monomer) of polyethylene is ethylene. This is just one small chemical step from ethanol, which can be produced by fermentation of agricultural feedstocks 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.

Genetically modified bioplastics
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.

Because of their biological degradability, the use of bioplastics is especially popular for disposable items, such as packaging and catering items (crockery, cutlery, pots, bowls, straws). The use of bioplastics for shopping bags is already 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.

Non-disposable applications include mobile phone casings, carpet fibres, and car interiors, fuel line and plastic pipe applications, and new electroactive bioplastics are being developed that can be used to carry electrical current. In these areas, the goal is not biodegradability, but to create items from sustainable resources.

Performance and usage
Many bioplastics lack the performance and ease of processing of traditional materials. Polyactic 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 percent of the biodegradable materials market. The most common end use market is for packaging materials. Japan has also been a pioneer in bioplastic, incorporating them into electronics and automobiles.

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