Plastics are made from long chain polymers and each polymer is composed of small building units called monomers that are chemically linked together. Different combinations of monomers yield polymers with different properties and characteristics. In addition, plastic additives are incorporated into polymers during the manufacturing process to confer specific properties to the polymer for certain packaging applications. For example, the introduction of nucleating agents improves the clarity and stiffness of a plastic polymer which allows it to be used for making rigid and clear containers that show-off the contents and appeal to consumers.
Plastic recycling is the process of recovering scrap or waste plastics and reprocessing the material into useful products, sometimes completely different from their original state.
The most-often recycled plastic, HDPE or number 2, is downcycled into plastic lumber, tables, roadside curbs, benches, truck cargo liners, trash receptacles, stationery (e.g rulers) and other durable plastic products and is usually in demand. The white plastic "peanuts" used as packing material are often accepted by shipping stores for reuse.
Plastics makes up around 7% of the average household dustbin.
Source:Analysis of household waste composition and factors driving waste increases - Dr. J. Parfitt, WRAP, December 2002
The quantity of plastic waste produced every year in the UK is estimated to be nearly 3 million tonnes. Approximately 56% of all plastics waste is used packaging, three-quarters of which is from households. It is estimated that only 7% of total plastic waste arisings are currently being recycled.
In addition, plastics production requires other resources such as land and water and produces waste and emissions. The overall environmental impact varies according to the type of plastic and the production method employed.
A report on the production of carrier bags made from recycled plastic instead of virgin polythene show that the use of recycled resulted in the following environmental benefits:
- 66% less energy consumption
- only a third of the sulphur dioxide and half of the nitrous oxide are produced
- reduction of water usage by nearly 90%
- reduction of carbon dioxide generation by two-and-a-half times
Another study concluded that 1.8 tonnes of oil are saved for every tonne of recycled polythene produced.
In 1991, LINPAC Plastics Recycling opened a unique plant with the ability to recycle post-consumer polystyrene products. The plant, based in Allerton Bywater, West Yorkshire, has a capacity of over 14,000 tones per year, which was set to increase to 25,000 tonnes per year by 2005. The plant is able to process fast food boxes, meat trays, egg cartons, yoghurt pots, vending cups, and a range of other polystyrene products. In addition, the plant processes a range of polyethylene and polypropylene goods.
In 1998, a pilot feedstock recycling plant went operational at BP's Grangemouth site in Scotland, with a capacity to process 400 tonnes of mixed plastic waste year. A feasibility study into its viability concluded that a 25,000 tonnes per annum plant could be supported from the area's municipal waste sources alone.
Many UK retailers have introduced degradable carrier bags in their stores. These bags are produced with plastic which degrades under certain conditions or after a predetermined length of time. Degradable plastic are available in two types: bio-degradable plastics, which contain a small percentage of non oil-based material, such as corn starch; and photodegradable plastics, which will break down when exposed to sunlight.
By definition �Degradable Plastic� means a plastic film containing a controlled percentage of an appropriate non-toxic, non-tinting additive, which will enable the plastic film to totally degrade when exposed to aerobic or anaerobic conditions, including when disposed in a landfill or other regulated dumping area, and within such period of time as specified.
Biodegradable plastics are plastics that will decompose in the natural environment. Biodegradation can be achieved by enabling microorganisms in the environment to metabolise the molecular structure of plastic films to produce an inert humus-like material that is less harmful to the environment.
Every year, an estimated 17� billion plastic bags are given away by supermarkets. This is equivalent to over 290 bags for every person in the UK.