Plastics and Synthetic Fibres
Intermediate 2 Chemistry
Unit 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 always have a C=C
• These join together in a reaction called
addition polymerisation.
– view animation
1
2
+
3
1
2
…
+
…
…
…
MONOMERS
3
POLYMERS
1
…
H
C
H
2
H
C
H
+
H
C
H
3
H
C
H
+
MONOMERS
H
C
H
1
H
C
H
…
H
C
H
2
H H H H
C C C C
H H H H
POLYMERS
3
H
C
H
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
C=C
H
H
C6H5 H
H
H
C6H5 H
H
H
C6H5 H
Poly(phenylethene)
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
OH
OH
C
CH 2
CH 2
OH
O C
C
CH 2
CH 2
O
O
C
O
O
CH 2
O
CH 2
HO
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.
Amides
• Formed when an amine reacts with an
alkanoic acid.
H
N
O
C
H OH
R
amine
R
1
carboxylic acid
R
H
O
N
C
amide
An AMIDE group
R
1
Polyamides
• Are condensation polymers.
• Formed when a diamine reacts with a
diacid.
Recently developed plastics
• Kevlar
– Very strong
• Poly(ethenol)
– Water soluble
• Biopol
– Biodegradable
Kevlar
Kevlar
Poly(ethenol)
Poly(ethenol)