synthetic polymers chemistry

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Synthetic

Polymers

By:

Soo Ying Yu

Sharanya Mohanadas

Christina Ong

Ng Yi Von

Tan Kah Peng

Polymers are large molecules made up of many smaller and identical repeating units joined together by covalent bonds . These molecules are called monomers .

Polymerization is the chemical process by which the monomers are joined together to form a big molecule known as a polymer .

A polymer is a macromolecules (a very big molecules) . Hence , the relative molecular mass of a polymer is large .

The properties of a polymer are different from its monomers .

POLYMERS CAN BE DIVIDED INTO 2 TYPES:

a) Naturally occurring polymers

Polymers that exists in living things in nature (plants and animals)

b) Synthetic polymer

Polymers that are man-made by chemical processes in the laboratories.

Natural polymers

Synthetic polymers

Exist in living things in nature (plants or animals)

Examples:-

(1) Protein

- amino acids protein

(monomer) (polymer)

(2) Carbohydrates

- glucose carbohydrate

(monomer) (polymer)

(3) Natural rubber

- isoprene natural rubber

(monomer) (polymer)

Polymers that are man-made by chemical processes in the laboratories

Many of the raw materials for synthetic polymers are obtained from petroleum, after the refining and cracking processes

Example:-

(1)Plastics

(2) Fibres

(3) Elastomer

2 types of polymerisation:-

Addition polymerisation

(2) Condensation polymerisation

Synthetic Polymer

Synthetic PolymerAdvantagesDisadvantagesThermoplasticsLightLow processing costsHigh strengthMeltDeformed when exposed to high levels of stress Chemical Leaching Thermosetretain their strength and shape even when heatedCannot be recycledCannot be remolded or reshapedElastomerRecyclable MaterialResistanceSoftRelatively high costIf heated to a relatively high temperature, they tend to lose their rubbery propertySynthetic fibercheaper than natural fiberEasy to wash and dry up quicklySynthetic fibers burn more easilyDamage by hot washing

Synthetic Rubber

made by mixing two by-products of petroleum refining, butadiene and styrene.

mixed with soapsuds to make liquid latex

then dried into bits and pressed into bales

about 70 percent of all

rubber is synthetic

Types of synthetic rubber

Plastics

Polyethene

Polyamide

Nylon 6-6

high mechanical strength, great rigidity, and good stability under heat is required

carpet fibres, tyres, zip ties, ropes, conveyor belts, hoses

ELASTOMER

A polymer that can regain its original shape after being stretched or pressed.

For example : Both natural rubber and synthetic rubber.

Two types of polymerization processes:

Addition polymerization

Condensation polymerization

Addition polymerization - Plastics such as polythene and PVC

Condensation polymerization - Synthetic fibers such as nylon and Terylene.

PROPERTIES OF SYNTHETIC POLYMERS

The physic properties of a polymer, such as its

strength and flexibility depend on :

Chain length the longer the chains the stronger the polymer

Side groups polar side groups give stronger attraction between polymer chains, making the polymer stronger.

Cross-linking if polymer chains are linked together extensively by covalent bonds, the

polymer is harder and more difficult to melt.

POLLUTION PROBLEM CAUSED BY SYNTHETIC POLYMERS

Non-biodegradable - cannot be decomposed by bacteria or other microorganisms.

Disposal problems - not decay like other organic garbage.

Discarded plastic items may cause blockage of drainage systems and rivers.

Flash floods

Plastic bottles and containers that are not buried in the ground will become breeding grounds for mosquitoes.

Dengue

4.Small plastic items that are thrown into the rivers, lakes and seas are sometimes swallowed by aquatic animals.

Animals die from choking

5.The open burning of polymers may release harmful and poisonous gases that will cause air pollution.

Burning of PVC will release hydrogen chloride gas which contributes to the acid rain problem.

METHODS TO OVERCOME ENVIRONMENTAL PROBLEMS OF POLYMERS

Reused - Collected and reused or reprocessed to make new items.

Reduce - Reduce the use of non-biodegradable polymers.

Recycle

DEVELOP BIODEGRADABLE POLYMERS

The polymers can be decomposed by bacteria, other microorganisms or simply by sunlight (photodegradable).

One type of biodegradable polymer was developed by incorporating starch molecules into the plastic materials so that they can be decomposed by bacteria.

Make the world a better place.

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