Notes On Fibres - CBSE Class 8 Science
All fabrics are materials made from many fibres, which are obtained from natural or artificial sources.  Cotton is a natural fibre obtained from the cotton plant. All synthetic fibres are man-made fibres that are prepared by a number of processes using raw material of petroleum origin, called petrochemicals. Synthetic fibres consists of many small units or monomers combine to form a larger unit called a polymer. (Pause) Polymer is a Greek word, formed by the combination of ‘poly’ which means many and ‘mer,’ which means part or unit. Thus,  a polymer is made up of many repeating units called monomers. Example Nylon, rayon, acrylic, polyester...etc Cotton is a form of polymer called cellulose, which is made of a large number of glucose units. Advantages of synthetic fibres        •  Synthetic fibres can be washed and dry quickly.        •  They do not wrinkle easily and are very durable.        •  They are less expensive when compared to natural fibres.        •  They are easy to maintain        •  They are readily available than natural fibres. Disadvanatges of synthetic fibres A big disadvantage of synthetic fibres is that they melt on heating.  Synthetic material catches fire, the fabric melts and sticks to the body of the person wearing it. This is extremely dangerous, so it is important not to wear synthetic clothes in the kitchen or laboratory. Rayon Fibre obtained by chemically treating wood pulp is called rayon or artificial silk. Rayon cannot be called a natural fibre as it is man-made. Characteristics of rayon        •  Rayon is cheaper than silk and can be woven like silk fibres.        •  It is highly absorbent, soft and comfortable.        •  It is easy to dye in a wide range of colours and drapes well. Uses of rayon        •  Rayon widely used in all types of clothing and home furnishings.        •  Rayon mixed with cotton to make bed sheets and curtains or with wool to make carpets. Nylon Nylon is a synthetic fibre made from coal, water and air. It is elastic, very lustrous and easy to wash. It dries quickly and retains its shape. Uses of nylon        •  Nylon is used to make seat belts in cars, curtains, sleeping bags, tents, tooth brushe bristles, socks and ropes,        •  It is also used to make parachutes and ropes for rock-climbing.        •  It is used to make fishing nets. Polyester Polyester is a synthetic fibre, derived from coal, air, water and petroleum. Polyester is made of repeating chemical units called esters. Poly  + Ester → Polyester - ester - ester - ester - ester - ester -  Fabrics which are madeup of polyester can be washed and dried quickly, Polycot is a mixture of polyester and cotton and polywool is a mixture of polyester and wool. Fabric made from polyester retains its shape and remains crisp. Polyester is easy to wash and dry. Terylene is a popular form of polyester, which can be drawn into very fine fibres. These fibres can be woven like any other yarn. PET or poly-ethylene terephthalate is another familiar form of polyester, which is used to make bottles, utensils, films and wires. Polyester is also used for making hoses, ropes, nets, thread, raincoats, fleece jackets, clothing and medical textiles. Acrylic Acrylic is a synthetic polymer of methyl methacrylate. Fabric made from acrylic is warm to wear, retains its shape and is durable.  Acrylic is easy to wash and dries quickly.  Acrylic is used in apparel like sweaters and socks and in home furnishings such as furniture, carpets, blankets and upholstery fabrics. Industrial uses of acrylic include craft yarns, awnings, boat and vehicle covers and luggage.

#### Summary

All fabrics are materials made from many fibres, which are obtained from natural or artificial sources.  Cotton is a natural fibre obtained from the cotton plant. All synthetic fibres are man-made fibres that are prepared by a number of processes using raw material of petroleum origin, called petrochemicals. Synthetic fibres consists of many small units or monomers combine to form a larger unit called a polymer. (Pause) Polymer is a Greek word, formed by the combination of ‘poly’ which means many and ‘mer,’ which means part or unit. Thus,  a polymer is made up of many repeating units called monomers. Example Nylon, rayon, acrylic, polyester...etc Cotton is a form of polymer called cellulose, which is made of a large number of glucose units. Advantages of synthetic fibres        •  Synthetic fibres can be washed and dry quickly.        •  They do not wrinkle easily and are very durable.        •  They are less expensive when compared to natural fibres.        •  They are easy to maintain        •  They are readily available than natural fibres. Disadvanatges of synthetic fibres A big disadvantage of synthetic fibres is that they melt on heating.  Synthetic material catches fire, the fabric melts and sticks to the body of the person wearing it. This is extremely dangerous, so it is important not to wear synthetic clothes in the kitchen or laboratory. Rayon Fibre obtained by chemically treating wood pulp is called rayon or artificial silk. Rayon cannot be called a natural fibre as it is man-made. Characteristics of rayon        •  Rayon is cheaper than silk and can be woven like silk fibres.        •  It is highly absorbent, soft and comfortable.        •  It is easy to dye in a wide range of colours and drapes well. Uses of rayon        •  Rayon widely used in all types of clothing and home furnishings.        •  Rayon mixed with cotton to make bed sheets and curtains or with wool to make carpets. Nylon Nylon is a synthetic fibre made from coal, water and air. It is elastic, very lustrous and easy to wash. It dries quickly and retains its shape. Uses of nylon        •  Nylon is used to make seat belts in cars, curtains, sleeping bags, tents, tooth brushe bristles, socks and ropes,        •  It is also used to make parachutes and ropes for rock-climbing.        •  It is used to make fishing nets. Polyester Polyester is a synthetic fibre, derived from coal, air, water and petroleum. Polyester is made of repeating chemical units called esters. Poly  + Ester → Polyester - ester - ester - ester - ester - ester -  Fabrics which are madeup of polyester can be washed and dried quickly, Polycot is a mixture of polyester and cotton and polywool is a mixture of polyester and wool. Fabric made from polyester retains its shape and remains crisp. Polyester is easy to wash and dry. Terylene is a popular form of polyester, which can be drawn into very fine fibres. These fibres can be woven like any other yarn. PET or poly-ethylene terephthalate is another familiar form of polyester, which is used to make bottles, utensils, films and wires. Polyester is also used for making hoses, ropes, nets, thread, raincoats, fleece jackets, clothing and medical textiles. Acrylic Acrylic is a synthetic polymer of methyl methacrylate. Fabric made from acrylic is warm to wear, retains its shape and is durable.  Acrylic is easy to wash and dries quickly.  Acrylic is used in apparel like sweaters and socks and in home furnishings such as furniture, carpets, blankets and upholstery fabrics. Industrial uses of acrylic include craft yarns, awnings, boat and vehicle covers and luggage.

#### Activities

Activity1: Girbau.com has developed interactive simulation regarding structure of a fabric, types of fabrics and classification of fibres. It also includes identification tests for different fibres and explanation of each of the fibres. Go to Activity

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