Plastics: Composition, Classification & Environmental Disadvantages of Plastic
The word “Plastic” is in a sense, the antonym of the word “Elastic”. An elastic material regains its original shape on being stretched or elongated. The plastic nature of the material does not permit the body to come back to its original phase once it has been deformed. All materials show both elastic and plastic properties. The difference arises in the application of the material and the amount of loads it can withstand within the limits of the two properties.
Plastics are one of the most widely used materials now days. We recognize plastic by its unique nature of flexibility and lightness. It can adapt into the most complex shapes possible. Plastics are used in almost every field we can think of. Even its production is cheap. Most of our common household items are made from plastic like chairs, plastic containers, plastic bottles, plastic covers, stationary, plastic glasses etc. Plastics are very good insulators of heat. Therefore they are also used widely for offering protection from hot objects.
In the early 19th century people used egg membranes, cellulose of plants and other such naturally occurring polymers as plastics. These are natural and therefore are decomposable. Later, technologies were made to bind or strengthen plastics from inorganic material. These are stronger and more tensile. But the inorganic plastics such as polystyrene and Poly Vinyl Chloride are hard to decompose and take thousands of years to do so. But what is this raw material made of? What makes it so popular? Is it environment friendly?
How is Plastic Formed?
“Plastic” is not one single material. There are many types of plastics which are made of synthetic and organic compounds. Several molecules of the same compound form inter linkages with each other to form long chains. These chains are called polymers (“poly” meaning “many” and “meros” meaning “parts”). The basic compound that is repeated in the polymer is called the “base unit” of the polymer. Polymers which possess high molecular mass or which are made up of a large number of base molecules are called plastics.
Composition of Plastic
The chain of the polymer is formed by multiple linkages of certain atoms of the compound, usually being carbon, oxygen or nitrogen. The property to form these chain linkages between similar atoms is called “catenation”. The polymeric linkage forms the “Backbone” of the polymer. The other functional groups hang from the backbone.
Examples of plastics
Polyethylene (commonly referred to as polythene and popularly used as carry bags in grocery stores and plastic bottles)
Poly Vinyl Chloride (commonly referred to as “PVC” and are used to make pipes and insulation material of wires)
Poly Tetra-Fluoro Ethylene (commonly known as “Teflon” and is popularly used as a coating for non-stick cookware)
Polyester (used in making fibres for textile industry)
Poly Ethylene Terephthalate (commonly referred to as “PET” and used to make bottles for carbonated drinks)
Poly Styrene (commonly used to make packaging foam material and plastic containers).
Classification of Plastics
There are many ways of classifying plastics. We can classify them depending on the scientific property which we desire. Suppose if we want to study the densities of the polymers, we must classify them based on their linkage type. They are classified into condensation polymers and addition polymers. We can classify them based on their thermal properties as “Thermoplastics” and “Thermo-setting plastics”. Basically thermo plastics are the ones which can be re-moulded once they take their initial shape unlike the thermo setting plastics which are “set” to maintain their desired shape resisting any changes. Environmental classification of plastics classifies it as bio degradable and non-bio degradable.
Environmental Disadvantages of Plastic
Plastics are tough to decompose or destroy by natural processes. They take thousands of years to decompose. So, when they are dumped on the ground, they settle there and block the passage of water and nutrients into soil making the place infertile. Most people try to dispose of plastic by trying to burn it. When it burns, it seems to be breaking down but it never does. It actually shrinks in size while being heated but never disintegrates and in addition, burning plastic releases a black smoke that consists of a highly carcinogenic chemical (cancer causing chemical). Another hazard arises even before plastic is manufactured. Plastics are manufactured from tiny pellets called “nurdles”. This causes a loss of life of birds and fishes which mistake it for food.
Recycle and Reuse
So, while plastic lasts for such a long period of time, why not use it rather than wasting it? Plastics can be used for a long time by “Recycling” it. Thermo plastics can be re-shaped and reused. Therefore by recycling plastic, we save the world and ourselves too in the process. Recycling technologies are still at its young ages. It is a laborious process to separate out so many different types of plastics. So, automation of recycling would save a lot of man force, avoid environmental pollution and loss of life.
Another option till then is to use biodegradable plastics. They are the plastics which disintegrate upon the action of natural decomposition methods like being disintegrated by bacteria, enzymes and environmental sources. They are totally environment friendly but not friendly to the pocket. Biodegradable packaging also in its child stages is quite an expensive option when large scale production is required.
Plastics have revolutionized the technology of mankind over the years from the transition from the metal ages. Still a lot of research is being carried out to make plastic the ultimate material which will have no side effects as well. Genetically engineered bacteria are under development which can disintegrate certain plastics. All said, plastics are certainly a fascinating material with wide usage field.