From Ecopedia

Overview

The term plastic commonly refers to a wide variety of synthetic and semi-synthetic organic materials used for manufacturing industrial products. Typically, plastics are polymers with high molecular mass, containing other substances as well to provide enhanced performance at reduced costs.

Meaning and Properties

Derived from the Greek term, “plastikos”, which means “fit for molding”, plastic refers to plasticity or malleability during manufacturing of products.

Plastics can be easily cast, pressed or extruded into various shapes such as fibers, films, boxes, bottles, tubes, plates and many more.

The very first man-made plastic, called Parkesine and later celluloid, was invented in 1885 by Alexander Parkes.

Plastic can be manufactured from:

- naturally occurring plastic materials such as shellac and chewing gum

- Chemically modified natural substances such as rubber, collagen, galalite and nitrocellulose, or

- Complete synthetic molecules such as epoxy, polyethylene, polyvinyl chloride (PVC) and bakelite

Types of plastics

Plastics can be classified into two types: 1. Thermoplastics, which soften and melt on heating 2. Thermosets, which take a permanent shape subsequent to melting and solidification

Common Examples:

- Nylon - Rubber - Synthetic rubber - Synthetic resin (Bakelite)

Uses

Plastics are used in an ever-increasing range of products, ranging from spaceships to paper clips. In the present-day world, traditionally used materials including stone, wood, paper, glass, ceramic and leather are being increasingly replaced with low-costing plastics.

As plastics are easy to manufacture, show high versatility and water impermeability, plastics offer a better and efficient alternative to traditional materials.

Environmental Information

Increased plastic usage across the world is posing serious environmental threat to the planet with irrevocable consequences. Plastic causes environmental hazards right from the stage of manufacturing to both disposal and recycling stages.

Manufacturing Phase Pollution

Major chemicals used for the manufacturing of plastic are found to be highly noxious, posing serious threat to all life on earth. During plastic production, large amounts of chemical pollutants including greenhouse gases are released in to the atmosphere causing global warming phenomenon.

Plastic disposal

The biodegradable nature of the plastics makes the material highly resistant to natural degradation processes. Since 1950s, plastic material amounting to a billion tons was discarded, which perhaps might persist for another hundred, thousand years in future. Burning plastic leads to toxic emissions such as dioxin (created on burning PVC) into the atmosphere causing major environmental hazards.

Threat to Marine life

Since plastic requires ultra-violet light with high energy for decomposition, large quantities of plastic waste is getting accumulated in oceans, causing dire threat to marine life. Many turtles, in particular, are dying by eating the plastic waste. Recently, a US report stated that every year over 100000 sea mammals expire by either eating or getting entangled in plastic waste. Among the entire sea population, seabirds of South Africa are found to be worst affected.

Plastic recycling

Recycling of plastic is often highly uneconomical, labour-intensive and involves a dirty and tedious procedure. Plastic recycling programs, involving remelting and reusing of thermoplastics as well as grounding of thermoset plastics for use as fillers, are increasingly implemented across the world today.

International Agreements on plastics Montreal Protocol Montreal Protocol committed member nations to ban the use of Chlorofluorocarbons (CFCs) for extruding polystyrene, as polystyrene production was found to contribute to ozone layer depletion.

References

http://en.wikipedia.org/wiki/Plastic http://inventors.about.com/od/pstartinventions/a/plastics.htm http://members.rediff.com/jogsn/BP4.htm http://www.dancewithshadows.com/business/pharma/plastic.asp