The name ‘Plastic’
Kinds of plastics
There are two main groups of Plastics:Thermoplastics and Thermosets
Thermoplastics become softens on heating and harden again when they cool. eg. polyethylene.
Thermosets become harden , when they are heated and cannot be softened by further heat e.g Bakelite
Thermoplastics become softens on heating and harden again when they cool. eg. polyethylene.
Thermosets become harden , when they are heated and cannot be softened by further heat e.g Bakelite
More than 50 families of plastics have been produced
Polyethylene (PE),Poly vinyl fluoride (PVF),Polypropylene (PP),Bakelite
Polyurethane,Nylon, Polyvinyl chloride (PVC),Terylene, Polystyrene (PS)
Cellulose acetate and Polycarbonates
Polyurethane,Nylon, Polyvinyl chloride (PVC),Terylene, Polystyrene (PS)
Cellulose acetate and Polycarbonates
Properties of plastics
Advantages
Plastics are good electrical / heat insulators.They do not corrode or decay.
They are relatively cheap to produce in large quantities.
They have good resistance to chemicals , water or grease.
Disadvantages
Plastics can either be non-biodegradable or degrade very slowly causing serious threat to natural environment.Plastics can contaminate foods with dangerous chemical compounds.
Plastics are flammable and release toxic fumes when burned.
Plastics usually have low melting points and therefore they expand with heat and eventually melt.
Plastics have low tensile strength and so they are not as strong as metals.
Environmental effects of Plastic pollution
Effect on land
Effect on Air
Several chemicals used in the manufacture of plastics are highly toxic and pose serious threat to all living species. (benzene, vinyl chloride, ethylene oxides, xyloms and Bisphenol A). During manufacture, plastic industries release greater amounts of carbon monoxide, dioxin and hydrogen cyanide. These gaseous pollutants contaminate air and cause respiratory diseases, nervous systems disorders and reduction of immunity to diseases in the human population. Burning of plastics release hazardous volatile organic compounds (VOCs) into the air.Effect on freshwater environment
Plastic wastes dumped into water resources contaminate and poisons freshwater life. On leaching in water, plastic can easily enter the food chain and harm human health. Plastic debris clog the sewage drains. Chocked drains cause flooding during the monsoons.Effect on marine environment
Effects of plastics on marine life include the entanglement and ingestion of debris by marine vertebrates and food-chain bioaccumulation of toxic additives by other species. Turtles become entangled in discarded nets and turtles were found dead with plastic garbage bags in the stomach. About 44% of sea birds eat plastic mistaken for food. Plastic is mistakenly eaten up by birds, turtles, seals and whales. This may choke them, poison them or impede digestion or cause starvation.Effect on Human Health
Toxic chemicals contained in plastics cause cancer, birth defects, hormonal changes, gastric ulcer, thyroid problems and cardiovascular diseases. The endocrine disrupting chemicals (EDCs) in plastics have been contributing to obesity and diabetes. The plastic bottles may leach cancer-causing and hormone - disrupting chemicals such as phthalates ( a component makes plastic pliable) and Bisphenol A ( a component harden plastics). Bisphenol A( BPA) a synthetic estrogen can affect the hearts of women and can permanently damage the DNA of mice.
Prevention of Plastic Pollution
REFUSE Single-use-plastics (SUPs) – Refuse plastic carry bags at the grocer’s shop. use natural fibre bags.REDUCE Waste – choose products with minimum plastic packaging.
REUSE – Preferably reuse non-toxic containers and goods.
RECYCLE – Recycling is not a sustainable solution. Recycling can be a last option.
No comments:
Post a Comment