plastics and synthetic fibres intermediate 2 chemistry unit 2(d)

Plastics and Synthetic FibresIntermediate 2 ChemistryUnit 2(d)

Examples of plastics

Examples of plastics• Polythene [poly(ethene)]• Polystyrene• Perspex• PVC• Nylon• Bakelite• Formica• Silicones

PVC [poly(vinyl chloride)]

Nylon

Bakelite

Formica

Silicones

Where do plastics come from?• Crude oil

– Fractional distillation– Cracking

• Alkenes

Uses related to properties• Flexible• Watertight• Shatter-proof• Light

Non-biodegradable

• Can’t be broken down by living things.• “Biopol” is a recently developed biodegradable

plastic.

Other problems with plastics• Low density• Durable• Burn or smoulder to give off toxic

fumes– Carbon monoxide– Hydrogen chloride– Hydrogen cyanide

Types of plastic• Thermoplastic

– Can be reshaped on heating

• Thermosetting plastic– Cannot be reshaped on heating

Chemistry of plastics• Plastics are examples of polymers

– These are long chain molecules made from smaller molecules joining together• These smaller molecules are called

monomers

• There are two types of polymer:– Addition polymer– Condensation polymer

Addition polymers

Addition polymers• Like all polymers, these are made from

monomers.• For an addition polymer, these

monomers are always alkenes.• These join together in a reaction called

addition polymerisation.– view animation

… …

MONOMERS POLYMERS

+ +… …

1 2 3 1 2 3

C

H

H

C

H

H

MONOMERS

1 2 3 1 2 3

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H

C

H

H++

POLYMERS

……

Naming polymers• The name of the polymer is made by

taking the name of the monomer, putting brackets around it, and adding “poly” in front– Poly(ethene) is made from ethene;– Poly(vinyl chloride) is made from vinyl

chloride.

Naming practice• Name the polymer made from:

– Propene– Chloroethene

• Name the monomer used to make:– Poly(heptene)– Poly(phenylethene)

Drawing polymers, monomers and the repeating unit

Condensation polymers

• What type of molecule is produced from an alkanol and alkanoic acid?– Esters

• Polyesters are made from similar molecules.

Polyesters

Monomers• Must have two functional groups per

molecule– For polyesters, they are a diol and a diacid

CO

OHC

O

OHCH2 CH2 OHHO

CH2 CH2 CH2 CH2O O

O

C

O

C O O

Condensation polymerisation• The joining up of two molecules,

producing water, is condensation.

• Because giant molecules are made, this is condensation polymerisation.

• Specifically with a diol and a diacid, a polyester is produced.

Polyamides• Are produced when an amine group

reacts with a carboxyl group.

Amines

H

N HH

Ammonia

N

H

H

H

H

N

H

CH3

Amides• Formed when an amine reacts with an

alkanoic acid.

H

N

H

RC

O

OHR1

amine carboxylic acid amide

An AMIDE group

N

H

R R1

C

O

Polyamides• Are condensation polymers.

• Formed when a diamine reacts with a diacid.