IntroductionProperties of plasticsPositive aspects of plasticsNegative aspects of plastics.types, categories andfamilies of plastics.Land plastic pollutionAir plastic pollutionWater plastic pollution.Ocean plastic pollutionHuman health hazardsPollution prevention
The word plastic was derived from the words plasticus(Latin for ‘capable of moulding’) and plastikos (Greek for ‘fit for moulding’). Plastics are organic polymers (synthetic or natural) of high molecular weight. The plastic is basically formless material which can be moulded under heat and pressure.
Most of the plastics are made from three raw materials • Non-renewable petroleum • Natural resource • Non-renewable Coal • Natural resource • Renewable cellulose • Natural resource
Plastic is a long, chain like molecules (polymers) made from petroleum capable being molded, extruded or cast into various shapes. The first plastic was invented in 1862 by Alexander Parkes. At first plastics could only be made in brown or black (Bakelite) color. In 1930’s, ‘Amino Plastics’ had been invented which could be made in lots of bright colours.
Plastics are strong, light weight, flexible and durable. Plastics show superior optical properties ( clarity, gloss and color). Plastics can be easily moulded into a variety of shapes and sizes. Plastics have excellent mechanical strength ( tensile properties, tear resistance and impact resistance ).
Plastics are relatively cheap compared to tin, glass and steel. Plastics are reusable and recyclable. Plastics have long use life.
Plastics are good electrical / heat insulators. Plastics do not corrode or decay. Plastics are cheap and dispensable. Plastics are resistant to chemicals, water or grease.
Plastics can either be non- biodegradable or degrade very slowly. Plastics are flammable and release toxic fumes when burned. Plastics can contaminate foods with dangerous chemical compounds. Plastics usually have low melting points and therefore expand with heat. Plastics are not as strong as metals.
plastics are made from fossil fuels. Fossil fuels contain hydrocarbons, which provide small building blocks called monomer polymerization. These hydrocarbon monomers are link together to form long carbon chains called polymers. The process of forming long molecules is called polymerization. The polymerization form viscous, sticky substances known as resins, which are used to make plastic products. For e.g., ethylene is a gaseous hydrocarbon. When it is subjected to heat, pressure, and certainpolyethylene. catalysts , the ethylene molecules join together into long, repeating carbon chains. These joined molecules form a plastic resin known as polyethylene.
Addition polymerization-Joining identical monomers• polyethylene, polypropylene, polyvinyl chloride, and polystyrene.Condensation polymerization-Joining two or more different monomers• nylon (polyamide), polyester, and polyurethane.
Groups of plastics Thermoplastics ThermosetsThermoplastics can be repeatedly softened Thermosetting plastics by heating and harden permanentlyhardened by cooling. after being heated once. e.g. polyethylene e.g. bakelite
No. type Chemical name usage precautions1 PET Polyethylene Single use bottles-water, soft drinks, Use with terephthalate juice caution High density Milk/detergentbottles Appears2 HDPE polyethylene safe3 PVC Poly vinyl chloride Meat wraps, shampoo Avoid containers More hazardous4 LDPE Low density Bread bags, Appears polyethylene Sandwich bags safe5 PP polypropylene Medicine bottles, cereal liners Appears safe6 PS polystyrene Take-out containers, foam avoid packaging7 O others Baby bottles, sauce bottles Use with caution
Polyethylene (PE) Polyester (PES) Poly vinyl chloride Polyamides (PA) (PVC) (Nylons). Polystyrene (PS) Poly tetrafluoroethylene Polypropylene (PP) (PTEE) (Teflon) Polyurethane (PU) Melamine formaldehyde polycarbonates (MF). Urea formaldehyde (UF). There are more than 50 families of plastics
Plastic Plastic wasteproduction disposal 100 million 25 million tonnes/ year tonnes/year Plastics in municipalAnnual increase of solid waste = 11.8 % Production =9% By weight
Polyethylene (PE) is a milky white, translucentsubstance derived from ethylene.Polyethylene (PE) is made in low- and high-densityforms.Low-density polyethylene (LDPE) is the most widely usedof all plastics, because it isinexpensive, flexible, extremely tough, and chemical-resistant. LDPE is molded into bottles, garment bags, frozen foodpackages, and plastic toys.High-density polyethylene (HDPE) is stiffer,stronger, and less translucent. HDPE is formed into grocery bags, car fueltanks, packaging, and piping.
Polyvinyl chloride (PVC) is prepared from theorganic compound vinyl chloride.PVC is the most widely used of the amorphousplastics. PVC is lightweight, durable, and waterproof.Rigid PVC is moulded into clearbottles, pipe, house siding, and gutters and isused to form other consumerproducts, including compact discs andcomputer casings.Soft form of PVC is used to make shrink-wrap, food packaging, rainwear, shoesoles, shampoo containers, floortile, gloves, upholstery, and other products.
Polypropylene ispolymerized from theorganic compoundpropylene.Polypropylene has theproperties of durabilityand chemicalresistance.Polypropylene madeintorope, fiber, carpet, and packaging film.
Polystyrene isproduced fromstyrene.polystyrene is anamorphous, transparent, and somewhatbrittle plastic.Polystyrene is madeinto products such astoys, utensils, displayboxes, model aircraftkits, and ballpoint penbarrels.
Polyethylene terephthalate (PET) is formed from the reaction of terephthalic acid and ethylene glycol. PET molecules are strong and abrasion- resistant material that is used to produce films and polyester fibers. PET is injection molded into windshield wiper arms, sunroof frames, gears, pulleys, and food trays.
80% ofthermoplastics, and 20% of thermosetplastic wastes aregenerated in India. The use of plastics inIndia is 3 kg perperson per year. The totalconsumption ofplastics in India isabout 4 million tonnesand the wastegenerated is about 2million tonnes. About 20% of solidmunicipal wastes areplastics in India.
Plastic is one of the toxic non-biodegradable pollutants, which pollutes land, air and water. Plastics cause serious damage to the environment both during its manufacture and disposal. The manufacture of plastics in industries releases huge quantity of carbon monoxide, dioxin, hydrogen cyanide and VOCs. These gases pollute air seriously. Being a non-biodegradable material, land filling with plastics preserves the poisons for ever.
Plastic is a part of our lives. People use plastics in a variety of ways ranging from household appliances to industrial and commercial products. The production of plastics is growing about 9% annually. According to an estimate about 100 million tonnes of plastics is produced every year all over the world.
The major chemicals used in the manufacture of plastics are highly toxic. Plastic which is made from petroleum, is a material that the earth cannot digest. These toxic chemicals( benzene, vinyl chloride, xylems and bisphenol A ) pose serious threat to living beings of all species on earth. Benzene and vinyl chloride are confirmed carcinogens. In the environment, plastic breaks down into smaller and smaller particles, that absorb toxic chemicals, are ingested by wildlife on land and in the ocean and enter human food chain.
ToxicBy-products/wastes incineration distribution End of lifeManufacture Use of Disposal of Land plastics fills Of plastics plastics recycling Leaching of chemicals& Enter human Food chain
Plastic resins are made by using non- renewable natural resources. Approximately 8 % 0f world’s oil production is used to make plastics. Over exploitation results in depletion of natural resources
Plastic pollution on land is both physical andchemical.Plastic reduces soil fertility by forming the partof manure for years.Plastic spoils environmental aesthetics andhygiene.Plastics in landfills emit hazardous VOCs duringincineration.Plastics in soil can lessen the growth of plantsand trees by blocking the absorption ofminerals, water and other nutrients.Plastics can cause land slides.
Industries emit large amounts of carbonmonoxide, dioxin and hydrogencyanide.These gaseous pollutants contaminateair and cause respiratorydiseases, nervous system disorders andimmune suppression in human beings.
Plastics wastes dumped in water courses contaminate and poisons freshwater life. On leaching in water, plastic can easily enter the human food chain and harm human health. Plastic debrises clog the sewage drains and create stagnant water which will be an ideal habitat for mosquitoes and other parasites. Chocked drains cause flooding during monsoons.
Effects of plastics onmarine life include theentanglement andingestion of plastic debrisby marine vertebrates .Over a million sea birdsand mammals dieannually from ingestionof plastics.Plastic is mistaken forfood and is eaten up bybirds, turtles, seals, andwhales. This may chokethem, poison them orimpede digestion andcausing starvation.
Marine turtles becomeentangled in discardednets and were founddead with plasticgarbage bags in thestomach.Some marine mammalsswallow plasticbags, which resemblejelly fish in sea water.About 44% of sea birdseat plastics mistaken forfood leading tosuffocation or blockageof digestive tracts andeventually death.
Toxic chemicals contained in plastics causeneurological problems, cancer, birth defects, hormonalchanges gastric ulcer, thyroid problems andcardiovascular disease.The endocrine disrupting chemicals(EDCs) in plasticshave been contributing to obesity and diabetes.The plastic bottles may leach cancer-causingchemicals such as phthalates (a component makesplastic pliable) and Bis-phenol A ( a component hardenplastic).Bis-phenol A(BPA) a synthetic estrogen, can affect thehearts of women and can permanently damage DNAof mice.
The raw material for plastic bags are petroleumand natural gas (manufacture take 4% of world’soil production).The plastic grocery bags are made from ethylene,a non-renewable resource.The plastic bags take 100s of years to break down. HDPE Chemical barrels polyethylene LDPE Thin filmy bags LLDPE Thick glossy bags
Prevention strategies REFUSE – REDUCE – RECYCLE – refuse REUSE – Choose Recycling isplastic carry products Reuse non- not abags at the with toxic sustainable grocer’s minimum containers solution. shop. Usenatural fiber plastic and goods. -can be last bags. packaging option.
Dr.B.Victor is a highly experienced postgraduate biology teacher, recently retired from the reputed educational institution - St. Xavier’ s College, Palayamkottai, India-627001. He was the dean of sciences and assistant controller of examinations. He has more than 32 years of teaching and research experience He has taught a diversity of courses ranging from pre- university to post graduate classes. Send your comments to : email@example.com