Present time is the age of plastics. Almost all the domestic items are now made up of plastics such as mug, bucket, chair, ballpen, etc., There is no end to the number of plastic items used by us. But, what are plastics?
Plastics are polymers made up of a very large number of small units joined end to end to form long chains. All plastics have the different type of arrangement of units. It may be either linear or cross-linked.
Plastics can be coloured and melted. It becomes soft on heating. It can be moulded into any desired shape and then again hardened to make a durable article. The property by the virtue of which a substance can easily be moulded into sheets or drawn into fibres on heating is called plasticity. Some common plastics are Bakelite, polythene, terylene and polyvinyl chloride (PVC).
Plastics that once moulded into a shape do not become soft on heating and can not be moulded again are called thermosetting plastics. They maintain their shape and size even at high temperatures. Example of thermosetting plastics are Bakelite, melamine and Formica.
Although different types of plastics differ in some of their physical and chemical properties, the following properties are common to most of them:
We know that metals like iron get rusted when left exposed to moisture and air. But plastics do not react with air and water and hence, do not get corroded. For this reason, polyvinyl chloride(PVC) is used for making water pipes (called PVC pipes), water tanks and sanitary fittings, soles of shoes and sandals, raincoats, handbags and bathroom curtains.
Thermocol is the most common example of plastic known for it's lightness and rigidity. It is used for making disposable cups and packaging materials for fragile items like computers, cell phones, television and refrigerator.
They can be moulded into different shapes and sizes. Plastics are generally cheaper than metals. Thus, they are widely used in industries and for making household articles. For example,
a) Melamine is used for making unbreakable dinnerwares, floor tiles, decorative objects, fire-resistant fabrics and kitchenwares.
b) Polythene is used for making carry bags, adhesive tapes and pipes to transport liquids.
c) PVC is used for making floor tiles, durable toys, furniture and bottles.
For this reason,
a) Bakelite is used for making handles of utensils.
b) Polystyrene is filled in the hollow walls of refrigerators, air coolers and thermos flasks. It is also used for making ice boxes.
For this reason,
a) Bakelite is used for making plugs and switches.
b) PVC is used as aninsulation cover in electric wires.
Teflin is used for making non-stick cookwares because it is a special type of plastic on which oil and water do not stick
Also, plastics are cheaper in comparision to metals and are easy to handle.
Plastics are polymers made up of a very large number of small units joined end to end to form long chains. All plastics have the different type of arrangement of units. It may be either linear or cross-linked.
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Plastics can be coloured and melted. It becomes soft on heating. It can be moulded into any desired shape and then again hardened to make a durable article. The property by the virtue of which a substance can easily be moulded into sheets or drawn into fibres on heating is called plasticity. Some common plastics are Bakelite, polythene, terylene and polyvinyl chloride (PVC).
KINDS OF PLASTICS
1. THERMOPLASTICS:
Plastics that easily deformed on heating and can be bent easily are called thermoplastics. They can be moulded into different shapes again and again by repeated heating and cooling. Examples of thermoplatics are polythene, polyvinyl chloride and polystyrene.
2. THERMOSETTING PLASTICS:
Plastics that once moulded into a shape do not become soft on heating and can not be moulded again are called thermosetting plastics. They maintain their shape and size even at high temperatures. Example of thermosetting plastics are Bakelite, melamine and Formica.
General Properties and uses of plastics
Although different types of plastics differ in some of their physical and chemical properties, the following properties are common to most of them:
1.PLASTICS ARE NON-REACTIVE-
We know that metals like iron get rusted when left exposed to moisture and air. But plastics do not react with air and water and hence, do not get corroded. For this reason, polyvinyl chloride(PVC) is used for making water pipes (called PVC pipes), water tanks and sanitary fittings, soles of shoes and sandals, raincoats, handbags and bathroom curtains.
2.PLASTICS ARE LIGHTWEIGHT-
Thermocol is the most common example of plastic known for it's lightness and rigidity. It is used for making disposable cups and packaging materials for fragile items like computers, cell phones, television and refrigerator.
3. PLASTICS ARE STRONG AND DURABLE:
They can be moulded into different shapes and sizes. Plastics are generally cheaper than metals. Thus, they are widely used in industries and for making household articles. For example,
a) Melamine is used for making unbreakable dinnerwares, floor tiles, decorative objects, fire-resistant fabrics and kitchenwares.
b) Polythene is used for making carry bags, adhesive tapes and pipes to transport liquids.
c) PVC is used for making floor tiles, durable toys, furniture and bottles.
4.PLASTICS ARE POOR CONDUCTORS OF HEAT:
For this reason,
a) Bakelite is used for making handles of utensils.
b) Polystyrene is filled in the hollow walls of refrigerators, air coolers and thermos flasks. It is also used for making ice boxes.
5.PLASTICS ARE POOR CONDUCTORS OF ELECTRICITY:
For this reason,
a) Bakelite is used for making plugs and switches.
b) PVC is used as aninsulation cover in electric wires.
6.PLASTICS ARE INERT TO CHEMICALS:
Teflin is used for making non-stick cookwares because it is a special type of plastic on which oil and water do not stick
Also, plastics are cheaper in comparision to metals and are easy to handle.
