9.3 POLYMERS

A WORD POLYMER IS A COMBINATION OF TWO GREEK WORDS, “POLY” MEANS “MANY” AND “MEROS” MEANING “PARTS OR UNITS”.

A POLYMER IS A LARGE MOLECULE WHICH IS FORMED BY REPEATED LINKING OF THE SMALL MOLECULES CALLED “MONOMERS”.

MORE MONOMER MOLECULES JOINED IN UNITS OF LONG POLYMER.

CHARACTERISTICS OF POLYMERS LOW DENSITY. LOW COEFFICIENT OF FRICTION. GOOD CORROSION RESISTANCE. GOOD MOLD ABILITY. EXCELLENT SURFACE FINISH CAN BE OBTAINED. ECONOMICAL. POOR TENSILE STRENGTH.  POOR TEMPERATURE RESISTANCE.  CAN BE PRODUCED TRANSPARENT OR IN DIFFERENT COLORS

APPLICATION OF POLYMERS1. MEDICINE:- MANY BIOMATERIALS, ESPECIALLY HEART VALVE REPLACEMENTS AND

BLOOD VESSELS, ARE MADE OF POLYMERS LIKE DACRON, TEFLON AND POLYURETHANE.

2. CONSUMER SCIENCE :- PLASTIC CONTAINERS OF ALL SHAPES AND SIZES ARE LIGHT WEIGHT AND ECONOMICALLY LESS EXPENSIVE THAN THE MORE TRADITIONAL CONTAINERS. CLOTHING, FLOOR COVERINGS, GARBAGE DISPOSAL BAGS, AND PACKAGING ARE OTHER POLYMER APPLICATIONS.

3. INDUSTRY:- AUTOMOBILE PARTS, WINDSHIELDS FOR FIGHTER PLANES, PIPES, TANKS, PACKING MATERIALS, INSULATION, WOOD SUBSTITUTES, ADHESIVES, MATRIX FOR COMPOSITES, AND ELASTOMERS ARE ALL POLYMER APPLICATIONS USED IN THE INDUSTRIAL MARKET.

4. SPORTS:- PLAYGROUND EQUIPMENT, VARIOUS BALLS, GOLF CLUBS, SWIMMING POOLS, AND PROTECTIVE HELMETS ARE OFTEN PRODUCED FROM POLYMERS.

CLASSIFICATION BASED ON SOURCE

1. NATURAL POLYMERS-IS A POLYMER THAT RESULTS FROM ONLY RAW MATERIALS THAT

ARE FOUND IN NATURE. EXAMPLE:- PROTEINS, CELLULOSE, STARCH, RUBBER.

SILK AND COTTON FABRICS ARE WOVEN FROM NATURAL POLYMER FIBERS.

• 2. SYNTHETIC POLYMERS• -DEVELOPED BY CHEMISTS IN RESEARCH LABORATORIES AND

MANUFACTURED IN FACTORIES EX. RUBBER, NYLON, POLYETHYLENE.

• POLAR FLEECE IS MADE FROM A SYNTHETIC POLYMER.

CLASSIFICATION BASED ON SOURCE

NATURAL POLYMERS

• FOUR TYPES OF POLYMERS PRODUCED IN PLANT AND ANIMAL CELLS ARE STARCHES, CELLULOSE, NUCLEIC ACID, AND PROTEINS.• STARCHES• -CONTAINS HUNDREDS OF GLUCOSE MONOMERS.• PLANTS STORE STARCHES FOR FOOD AND TO BUILD STEMS, SEEDS AND

ROOTS. • FLOUR FOR THE BREAD IS MADE BY GRINDING THE SEEDS OF GRAINS

LIKE WHEAT AND CORN.• SIMPLE SUGARS, SUCROSE, AND POLYMERS BUILT FROM SUGAR

MONOMERS ARE CLASSIFIED AS CARBOHYDRATES

• CELLULOSE• -CONTAIN 3000 OR MORE GLUCOSE MONOMERS; GIVES

STRENGTH TO PLANT STEMS AND TREE TRUNKS• THE CARBOHYDRATE CELLULOSE IS THE MAIN COMPONENT OF

COTTON AND WOOD. IT IS THE MOST ABUNDANT OF ALL ORGANIC COMPOUNDS FOUND IN NATURE.• MOST ANIMALS CANNOT DIGEST CELLULOSE.

NATURAL POLYMERS

• NUCLEIC ACID• -MOLECULES IN A CELL THAT SORE

INFORMATION ABOUT ITS STRUCTURES AND FUNCTIONS• -LARGE NITROGEN CONTAINING

POLYMERS FOUND MAINLY IN THE NUCLEI OF CELLS.• TWO TYPES: DNA & RNA

NATURAL POLYMERS

• PROTEINS• - A POLYMER IN WHICH AT LEAST 100 AMINO ACID MONOMERS ARE LINKED THROUGH

BONDS BETWEEN AN AMINO GROUP AND A CARBOXYL GROUP. • AMINO ACID- A COMPOUND THAT CONTAINS BOTH CARBOXYL AND AMINO FUNCTIONAL

GROUP IN THE SAME MOLECULES• THE INSTRUCTIONS FOR MAKING PROTEINS ARE STORED IN THE DNA.• PROTEINS MAKE UP THE FIBERS OF YOUR MUSCLES, YOUR HAIR, FINGERNAILS AND THE

HEMOGLOBIN IN YOUR BLOOD.• YOUR BODY MAY CONTAIN AS MANY AS 300,000 DIFFERENT PROTEINS.

NATURAL POLYMERS

SYNTHETIC POLYMERS

• RUBBER• - THE SUPPLY OF NATURAL RUBBER IS

LIMITED SO CHEMISTS WORKED HARD TO PRODUCE RUBBER USING HYDROCARBONS FROM PETROLEUM. TIRES WILL RESIST WEAR AND BE LESS LIKELY TO LEAK OF THEY ARE MADE OF SYNTHETIC RUBBER; ALSO USED AS AN ADHESIVE; USED TO MAKE ROPES AND PLASTIC OBJECTS

• NYLON• 1930- WALLACE CAROTHERS WAS TRYING

TO PRODUCE A SYNTHETIC POLYMER TO REPLACE SILK, PRODUCED NYLON INSTEAD• VERY STRONG, DURABLE, SHINY• USED IN PARACHUTES, WINDBREAKERS,

FISHING LINE, CARPETS AND ROPES

SYNTHETIC POLYMERS

• POLYETHYLENE• - FORMS WHEN ETHYLENE MOLECULES LINK HEAD TO

TAIL. THE MORE CARBON ATOMS IN THE CHAIN THE HARDER THE POLYMER• -USED TO MAKE PLASTIC MILK BOTTLES, PLASTIC

WRAP, PLASTIC SHAPES

SYNTHETIC POLYMERS