Science ch-3 SYNTHETIC FIBRE AND PLASTIC // important notes //Ak learning // Ak Raj..!
CH-3
SYNTHETIC FIBRE AND PLASTIC
IMPORTANT NOTES:-
FIBRES:-
- Fibres are very thin ,thread like strands from which clothes are made is called fibre.
- Fibre are two types
- Natural fibres
- Synthetic fibres
Natural fibres:-Those fibres which we obtained from nature (plants and animals) is known as natural fibres.
- Cotton
- Jute
- Wool
- Silk
Synthetic fibres:- Synthetic fibres are those fibres which are made made by human being. It is also called artificial fibre.
- Rayon
- Nylon
- Polyester
- Acrylic
RAYON:-
- Silk fibre obtained from silkworm was discovered in china. And it is kept as a closely gaurded secret for long time.
- Fabric obtained from silk fibre was very costly.But its beautiful texture fascinated everybody.
- Attempts were made to maek silk artificially.
- Towards the ends of nineteenth century, scientists were successful in obtaining a fibre having properties similar to that silk. Such a fibre obtained by chemical treatment of wood pulp. The fibre was called rayon or artificial silk.
- Rayon is obtained from a natural source , wood piulp, yet it is a man made fibre. So It called semi-synthetic fibre.
- It is cheaper than silk and can be woven like silk fibres.
- It can also dyed in a wide variety of ccolours.
- Rayon is mixed with cotton to make bedsheets or mixed with wool to make carpets.
NYLON:-
- Nylon is a anothre type of synthetic or man-made fibre.
- In 1931, It was made without using any natural raw material (from plants to animals)
- It was prepared from coal, water and air.
- It was first fully synthetic fibre.
- Nylon fibre was strong, elastic and lightweight.
- A nylon thread is actually styronger than steel wire.
- It was lusterous and easy to wash.
- It was become very popular for making clothes.
- Some examples:-
- Ropes
- Socks
- Tents
- Toothbrush
- Car seat belts
- sleeping bags
- Curtains
It is also used for making parachutes and ropes for climbing.
POLYESTER:-
- Polyester is another type of synthetic fibres.
- It is a category of polymer which contain an ester group in their main chain.
- There are many polyester but this term is widely used for specific material that is PET (Polyethylene terephthalate)
- It is very strong.
- It is very durable, resistant to chemicals, to sprinkage, etc.
- It is hydrophobic in nature and quick drying.
- It retains its shape.
- It is easily washed and dried.
- It is used to worked to make polyester suits
- It is used in making ropes in industries (mats, ropes)
- PET bottles are commonly used.
Polyester (poly+ester) is actually made up of a chemicals called ester. Ester are the chemicals which gives fruits like smell. Fabrics aresold by names like polycot, polywool,terrycot, etc. As the name suggests , these are made by mixing two types of fibres. Polycot is a mixture of polyester and cotton. Polywool is a mixture of polyester and wool.
ACRYLIC:-
- Acrylic are synthetic fibre made from polymer (polyacrylonitrile).
- It is warm and light.
- It is soft and flexible.
- It is resistant to moths and chemicals.
- It gives wool like feel.
- It is used in making, Blanket, Cashmere, Shawls,etc.
All the synthetic fibres are prepared by a number of process using raw materials of petroleum origins, called petrochemicals.
3.3 CHARACTERISTICS OF SYNTHETIC FIBRES:-
- Synthetic fibres posses unique characteristics which makes them popular dress materials.
- They dry up quickly , are durable, less expensive, readily available and easy to maintain.
PLASTICS:-
- Plastics is also a polymer like the synthetic fibre. All the plastics do not have the same type of arrangment of units.
- In some it is linear, whereas in some others it is cross linked.
- Plastics article are available an all possible shapes and sizes.
- Polythene (poly+ethene) is an example of plastics. It is used for making commonly used polythene bags.
- The plastics is easily mouldable i.e. can be shaped in any form.Plastics can be recycled, reused, coloured, melted, rolled into sheets or made into wires.
- Some plastics articles can be bend easily while some break down forced to bend. When hot water is added to a plastics bottles it gets deformed. Such a plastic which gets deformed easily on heating and can be bent easily are known as thermoplastics.
- Polyethene and PVC are the some examples of thermoplastics.These are used for manufacturing toys, combs and various types of containers.
- Some plastics which when moulded once, can be softed by heating. These are called thermosetting plastics. Bakelite and Melamine are two examples of thermosetting plastics.
- Bakelite is a poor conductor of heat and electricity. It is used for making electrical switch, handles of various untensils, etc.
- Melamine is a verstile material. It resists fire and can tolerate heat better than other plastics. It is used to make floor tiles, kitchen ware and fabrics which resists fire.
3.5 PLASTICS AS MATERIAL OF CHOICE
- It is the choice of most of the people because of these reason:-
- These are lightweight.
- These are lower in price.
- It has good strenght and easy to handling.
- Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts too.
- Slippers, furniture, decoration pieces, etc. are some examples made by plastics.
Properties of plastics:-
- Plastics is non reactive.
- Plastics is light, strong and durable.
- Plastics are poor conductor.
Plastics is non reactive:-
- Plastics do not react with water and air.
- They are not corroded easily.
- They are used to store various kind of material, including many chemicals.
Plastics is light, strong and durable:-
- Plastics is very light, strong, durable and can be moulded into different shapes and sizes.
- It is used in various purpose.
- Plastics are cheaper than metals.
- They are widely used in industry and for household works.
Plastics are poor conducter :-
- Plastics are poor conducter of heat and electricity.
- Plastics are used in handles of srew drivers and covering of electrical wires.
- Handles of frying pan are also made of plasitcs.
- Plastics find extensive use in the healthcare industry, some examples of their use are packing of tablets, threads, used for stitching wounds. syrings, soctors gloves and a number of medical instrument.
- Special plastics cookware is used in microwave ovens for cooking food. In the microwave ovens the heat cooks the food but does not affec the plastic vessels.
- Teffon is a special plastic on which oil and water do not stick. It is used for non-stick coating on cookwares.
- Fire-proof-plastics: Although synthetic fibres catches fire easily, it is interesting to know that the uniforms of firemen have a coating of melmine plastics to make them flame resistants.
3.6 PLASTICS AND THE ENVIRONMENT:-
- A material which gets decomposed through natural processes, such an action by bacteria, is called biodegradable.
- A material which is not easily decomposed by natural processes is termed as non-biodegradable.
- Plastics takes several years to decompose.
- It is not environment friendly.
- It causes environmental pollution.
- The burning process is the synthetic material is quite slow and does no brunt easily. In this process it release lots of poisonous funes into the atmosphere causing air pollution.
To make our environment clean:-
- Avoid the use of plastics as far as possible.
- Make use of bags made of cotton or jute. When you are go for shipping.
- The biodegradable and non-biodegradable wastes are collected separatly and disposed off separatly.
- It is better to recycle plastic wastes. Most of the thermoplastics can be recycled.
As a responsible citizens remember the 5R principle , Reduce, Reuse, Recycle, Recover and Refuse. Develop habits which are environment friendly.
- Do not through plastic bags in the water bodies or on the road.
- Take a cotton carry bags or a jut bags while going for shipping.
- Try to minimise the use of plastics materials e.g. use a steel lunch box instead of plastic one.
- For more details visit my website Ak4learning
- AK Raj
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