ANDChemistry/Chemistry Assignments/Study material on Plastics
Whether you are aware of it or not, plastics is a very important part of your life. The versatility of plastics allows it to be used in everything from automobile parts to doll parts, from soft drink bottles to the refrigerators they are stored in. Plastics is everywhere. from the car in which you drive to work, to the television you watch when you get back home, plastics help make your life easier and better. So how did plastics become the material of choice for so many varied applications?
The simple answer is that Plastics is the material that can provide you with what you want and need. Plastics have the unique capability to be manufactured to meet very specific functional needs of consumers. So maybe there's another question that's relevant: What do I want? Regardless of how you answer this question, plastics can probably satisfy your needs.
When we hear the term green living many of us think and visualize the outdoors - trees, mountains, and lush green lawns. In fact, one can start living green indoors itself, by choosing recycled products, finding new and creative uses for old items and cutting back on our use of natural resources. Green living is best defined as protecting the environment, by conserving and effectively using resources.
Plastics contribute to our health, safety and peace of mind in endless ways. The material possess an incredible history, consisting of a long line of innovation, giving birth to many uses of plastics as an environmentally friendly material.
Plastics for the most parts are derived from petroleum and natural gas and have heating values measured in British thermal units (Btus), competitive with coal and heating oil and more superior to wood, paper and other biomass fuels. Because of their high heating value, the residual plastics in municipal solid waste can provide an excellent fuel for modern waste-to-energy conversion plants. Recovery is a process of obtaining material or energy resources from solid waste. Recovered plastics can be recycle into new products or used in process engineered fuels, as done internationally, where collected plastics are processed with the paper into fuel pellets and then used in consumption with coal and other fuels in industrial boilers and utility plants.
Frequently asked questions
Q. 1. Are Plastics eco-friendly? Ans In General all man-made products, during manufacture, processing and disposal, have an impact on the environment. The issue therefore is, which of these products under consideration, will impose the least burden on the environment, and contribute to what is termed - 'sustainable development'.As you read on, the haze created by the media might clear to reveal the genuine role of plastics in the environment.
Q. 2.Are plastics harmful to plant growth, when buried in the soil?
Ans. NO. The use of polythylene nursery bags for growing seedlings for plantation crops or for afforestation is an application which is widely previling all over the world. The thin polyethylene bag holding the soil and sapling is slit with a blade and covered by soil. This way the root zone of the young sapling is not disturbed. In the conventional method the sapling had to be uprooted from a bamboo wicker basket, which increased the mortality rate of the young sapling. Plastics are inert and their presence under the soil has no affect on the soil chemistry or plant growth.
Q. 3.Are plastics responsible for utilising a major share of the world's oil or hydrocarbon resources?
Ans. NO.It is important to recognise that plastics use less than 4% of the world's hydrocarbon resources. Approximately 90% is consumed for transportation, power generation and heating.In general plastic products require less energy than products made from conventional materials, at comparableuse and performance levels.
Q. 4.Do Plasticss make-up a large part of the Municipal solid waste?
Ans. NO, A study conducted by the National Environmental Engineering Reasearch Institute, Nagpur for the BMC, putsthe figure at 0.75%.Even in Europe and U.S.A., with per capita consumption of plastics at over 50 kgs per annum (India is 2.7 kgsper annum), plastic waste makes up 8% of the total muncipal solid waste. The rest is made up of organic materials (33%), paper & board (30%), glass and metals (16%) and others (13%).
Plastics make a significant contribution by reducing the weight and volume of materials that are typically thrownaway. Unfortunately in India, waste is littered, instead of being disposed to facilitate collection and recycling.
Q. 5. Do Plastic grocery bags block drains during the rains?
Ans.Unlikely.Plastic grocery bags are lighter (less dense) than water; hence, they float. This is why they accumulate on the beaches when disposed indiscriminately. In the case of a vertical grill in the drainage system, the water will flowthrough the grill with the plastic bags floating on the surface. In the case of a horizontal grill such as the one found on the roadside, the bags will be displaced by flowing water. By applying this logic, it is difficult to understand how plastic grocery bags are responsible for blocking drains. Perhaps, someone should carefullyobserve and determine what is the real porblem.
Q. 6. Are plastics toxic when used in contact with foods and medicines?
Ans. NO.Plastics are used world-over because they are safe for packaging of foods, medicines and child care products. A few examples are - milk pouches, edible oil container, ice-cream packs, blister packs for tablets and capsules.I.V.fluids and blood is collected and stored in plastic bags. While plastics are safe for packaging of food and medicinal products, there are standards in each country,which specify the type of Additives and Pigments, which can be used safely for contact with foods.
Q. 7. Does the burning of plastic generate toxic fumes?
Ans. NO.To a large extent, post-consumer waste is made up of grocery or polyethylene bags. The chemical structure of polyethylene is made up only by carbon & hydrogen atoms. Anyone, who has done elementary chemistry will know that burning a carbon hydrogen molecular chain will generate carbon-dioxide and water vapour. A product made from PVC, when burnt in an open fire will emit hydrogen chloride fumes which are pungent. In fact this property has a singnificant advantage in retarding propagation of a flame when used as a sheath in a power cables. Normally a PVC product or a post consumer pack is extremely rare, in Municipal solid waste. The toxic fumes which the public wrongly believe are generated from plastics, are the result of burning materials contained in the bag, to get ride of industrial wastes.
Q. 8. Should we change over from plastic to paper bags?
Ans. A decision should be made after considering these facts.
- The wide spread belief that substitution of plastics with paper is more favourable to the environment, is not supported by facts and a L.C.A. -The manufacture of paper bags requires two-and-half times the energy as compared to plastic bags of the same size and for comparable performance. -The manufacture of paper produces singnificantly higher air pollutants. There is a huge disparity in waste water discharge in manufacture or recycling of paper. -As far as biodegradability is concerned, the University of Arizona study shows that newspapers burried in 1952 in land-fills and excavated in 1989, were legible. The same observation was made with telephone directories. -Some will argue that paper comes from trees which is a renewable resource; while plastic is manufactured from oil, which cannot be replaced. The argument against this is, that forests play an important role in protecting our soil bank and maintaining the gaseous balance in our atmosphere, by absorbing carbon dioxide and in turn releasing oxygen. In our hunger for wood, 44 million hectares of forests have been felled since Independence, making this country a land with one of the lowest areas under forest cover (area under forest to total land area). Therefore, as far as India is concerned land is not a renewable resource.
Q. 9. Who should take responsibility for the plastics environmental issue?
Ans. We all share the responsibility for environmental issues. Any issue which concerns and community, has to be resolved with the co-operation of all involved; it is a "shared responsibility". Those involved are Government, Municipalities, the raw material manufacturers, the retailers, and consumers. Because domestic waste is a mixture of materials of which plastics is only a small component, under 2% by weight, it is the responsibility of government to manage waste and a regulate its disposal. It is the responsibility of the plastics raw material and packaging manufacturers to come up with the most cost efficient solutions, which will preserve and protect goods, minimise the use of energy and reduce the weight and volume of waste. Food and personal product manufacturers, retailers and consumers need to be aware of the benefits of plastics pacakging and the need to dispose plastics in a manner which leads to increasing emphasis on recycling. Everyone must understand that the environmental legacy we leave behind for future gnerations will depend on our resolve to : REDUCE - REUSE - RECYCLE