CHAPTER 3 SYNTHETIC FIBRES AND

PLASTICS

INTRODUCTION

•THE CLOTHES WHICH WE WEAR ARE MADE OF FABRICS.

•FABRICS ARE MADE FROM FIBRES.

•THE FIBRES ARE OBTAINED FROM NATURAL OR ARTIFICIAL SOURCE.

NATURAL FIBRES

•THE FIBRES THAT ARE OBTAINED

FROM PLANTS OR ANIMALS ARE

CALLED NATURAL FIBRES.

•EXAMPLES : - COTTON , WOOL ,

SILK , JUTE , etc.

SYNTHETIC FIBRES

• THE FIBRES MADE BY HUMAN BEINGS ARE

CALLED SYNTHETIC FIBRES OR MAN MADE

FIBRES OR ARTIFICIAL FIBRES.

• SYNTHETIC FIBRES ARE MADE FROM

DIFFERENT CHEMICALS , HENCE EACH KIND

OF SYNTHETIC FIBRES HAVE THEIR OWN

PROPERTIES.

WHAT ARE SYNTHETIC FIBRES

• A SYNTHETIC FIBRE IS A CHAIN OF SMALL

CHEMICAL UNITS JOINED TOGETHER .

• EACH SMALL UNIT IS CALLED A

MONOMER.

• A LARGE CHAIN FORMED BY MANY

MONOMERS IS CALLED A POLYMER.

•THE WORD “POLYMER”

COMES FROM TWO GREEK

WORDS ;

POLY MEANING MANY

MER MEANING PART / UNIT.

SO A POLYMER IS MADE OF

MANY REPEATING UNITS

• THE STRUCTURE OF

POLYMER CAN BE

COMPARED TO THAT

OF A BEAD NECKLACE

– THE BEAD BEING

MONOMERS .

• THE PROCESS OF

COMBINING THE

MONOMERS TO FORM A

POLYMER IS CALLED

POLYMERISATION.

TYPES OF SYNTHETIC FIBRES

•RAYON

•NYLON

•POLYESTER

•ACRYLIC

RAYON

RAYON

•RAYON IS PREPARED BY CHEMICAL TREATMENT OF WOOD PULP.

• IT IS ALSO CALLED ARTIFICIAL SILK.

•ALTHOUGH RAYON IS OBTAINED FROM A NATURAL SOURCE (WOOD PULP) , YET IT IS A MAN MADE FIBRE.

PROPERTIES OF RAYON

EASILY DYED AND

WOVEN INTO

CLOTH

CHEAPER THAN SILK

LUSTROUS IN APPEARANCE

GOOD ABSORBENT OF SWEAT

USES OF RAYON

•RAYON IS MIXED WITH

COTTON TO MAKE BEDSHEETS

•RAYON IS MIXED WITH WOOL

TO MAKE CARPETS.

NYLON

• IN 1931 , IT WAS MADE WITHOUT

USING ANY NATURAL RAW MATERIAL

( FROM PLANTS OR ANIMALS )

• IT WAS PREPARED FROM COAL , WATER

AND AIR.

• IT WAS THE FIRST FULLY SYNTHETIC

FIBRE

PROPERTIES OF NYLON

STRONG

ELASTIC

LIGHT LUSTROUS

EASY TO WASH

USES OF

NYLON

PARACHUTE

SLEEPING BAGS

CAR SEATBELTS

TOOTHBRUSH

TENTS ROPES

SOCKS

ROPES FOR

ROCK CLIMBING

CURTAINS

POLYESTER

• POLYESTER (POLY + ESTER ) IS MADE UP

OF THE REPEATING UNITS OF A

CHEMICAL CALLED AN ESTER

• ESTERS ARE CHEMICALS WHICH GIVE

FRUITS THEIR SMELL

• FABRIC MADE FROM POLYESTER

DOESNOT GET WRINKLED EASILY

PROPERTIES

DOES NOT GET

WRINKLES

REMAINS CRISP

EASY TO WASH

DRIES QUICKLY

USES

• TERYLENE IS POPULAR POLYESTER WHICH

CAN BE DRAWN INTO VERY FINE FIBRES .

• PET IS A FORM OF POLYESTER WHICH IS

USED FOR MAKING BOTTLES ,UTENSIL ,

FILMS , WIRES AND MANY OTHER USEFUL

PRODUCTS

ACRYLIC

ACRYLIC

•ACRYLIC IS A SYNTHETIC FIBRE.

•DUE TO ITS WOOL-LIKE

FEEL,ACRYLIC FIBRE IS OFTEN

USED AS A SUBSTITUTE FOR

WOOL.

PROPERTIES

RESISTANT TO MOTHS

SOFT WITH CRIMPS

RESEMBLING WOOL

IS DURABLE LIGHT AND WASHABLE

STRONG AND STAIN RESISTANT

WARM AND LIGHT

WEIGHT

CAN BE DYED IN

DIFFERENT COLOURS

USES

ACRYLIC KNITTING WOOL IS GOOD FOR BABY AS IT IS SOFT , WARM AND

WASHABLE

USED FOR MAKING ARCYLIC FUR , BLANKETS

CARPETS

TRANSPARENT TYPE OF ACRYLIC IS USED TO COVER CAR HEADLIGHT ,

LENSES , SURGICAL

EQUIPMENTS

CHARACTERISTICS OF SYNTHETIC FIBRES

SYNTHETIC FIBRES ARE-

• STRONG

• DURABLE

• WRINKLE RESISTANT

• LIGHTWEIGHT

• EXTREMELY FINE

• NOT ATTACKED BY MOTHS

• LESS EXPENSIVE

• READILY AVAILABLE

DISADVANTAGES

1. DON'T ABSORB MOISTURE

SYNTHETIC FIBRES DONOT ABSORB

SWEAT , TRAPPING HEAT IN OUR BODY

2. DANGEROUS NEAR FIRE AS THEY

CATCH FIRE EASILY

3. THEY CANNOT BE EASILY IRONED AS

THEY MELT EASILY.