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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.