Brown's GCSE/IGCSE KS4 science-CHEMISTRY Revision Notes
Oil, useful products, environmental problems, introduction to
7. Making Polymers, plastics, uses, problems and recycling
Polymers are very long
molecules and the main component in many common plastic materials. On this page
the molecular structure, production-manufacture, uses and recycling of the polymers poly(ethene), poly(propene),
poly(chloroethene)/PVC and polystyrene are described. Problems with waste
plastics and methods of recycling of plastics are discussed.
Index of KS4 Science GCSE/IGCSE
Chemistry Oil & Organic Chemistry Pages: 1.
Fossil Fuels : 2. Fractional distillation of crude oil & uses of fractions : 3.
ALKANES - saturated hydrocarbons and combustion : 4.
Pollution, carbon monoxide, nitrogen oxides, what
makes a good fuel?, climate change-global warming :
5. Alkenes - unsaturated hydrocarbons :
6. Cracking - a problem of supply and demand, other products :
7. Polymers, plastics, uses and problems :
8. Introduction to Organic Chemistry - Why so many series of
organic compounds? : 9. Alcohols - Ethanol
- properties, reactions, biofuels :
10. Carboxylic acids and esters : 11. Addition
polymers and condensation polymers :
12. Natural Molecules - carbohydrates - sugars
- starch : 13. Amino acids, proteins,
enzymes & chromatography : 14. Oils, fats,
margarine and soaps :
15. Vitamins, drugs-analgesic medicines & food
additives and aspects of cooking chemistry! : 16. Ozone, CFC's and free
radicals : 17. Extra notes, ideas and links on
Global Warming and Climate Change : Multiple Choice and Gap-Fill Quizzes:
m/c QUIZ on Oil Products (GCSE/IGCSE easier-foundation-level)
m/c QUIZ on Oil Products (GCSE/IGCSE harder-higher-level) :
IGCSE/GCSE m/c QUIZ on other Aspects of Organic Chemistry
3 Easy linked GCSE/IGCSE Oil Products word-fill worksheets
Introducing polymers and plastics
7a. The formation
of POLYMERS and the USES of PLASTICS - Macromolecules
Reactions of alkenes (4)
(See also section 11.
More on other types of polymers)
The formation of big
polymer molecules called polyalkenes from small molecules called alkenes
Alkenes are made by
cracking some of the
fractions obtained by the fractional distillation of crude oil
The diagram below shows the general equation
for the formation of a plastic polymer from alkenes.
There are many different alkenes, so there
are many different polymers with a range of physical properties eg strength.
When catalysed and heated under pressure,
link together when 'half' of the double bond opens. The spare
bond on each carbon atom of the double bond are
used to join up the molecules.
The general equation for polyalkene
formation is shown in the diagram above.
The essential molecular
linking is equivalent to ...
... C=C + C=C + C=C
... etc. ===> ... C-C-C-C-C-C ... etc.
The original small
molecule is called the monomer
and the long molecule is called the polymer,
which is the sort of molecule most plastics consist of.
So lots of small molecules join up to form a
big long molecule in a process called addition polymerisation
and the polymers are named as poly(name of original alkene), i.e.
poly(alkene) and several examples are shown below.
7b. Examples of
poly(alkene) polymer molecules - formation, structure
A 'picture' of a section of a very long chain
molecule, essentially consisting of hundreds or thousands of -CH2-CH2-
ethene units all joined together.
Above is a 'ball and stick' type of model
and below is a 'space-filling' model.
Although it looks straight, in
reality, the long molecule will be all twisted-jumbled up like in the
diagram on the right above.
from ethene is a cheap but very useful plastic used for plastic bags and
bottles (old or commercial names: polyethylene, polythene and polyethene).
It is an example of a thermoplastic, because it can be heated to soften
it, reshape it e.g. in an injection mould system, and on cooling retains
its new shape - bottle, bowl, toy etc.
from propene is
stronger and more hard wearing than
polythene and is used for making crates, fibres and ropes (old or
commercial names: polypropylene, polyprene and polypropene).
made from chloroethene (old names vinyl chloride and
polyvinyl chloride from which PVC is derived)
much tougher than poly(ethene), very hard wearing with good heat
stability, so is used for covering electrical wiring and plugs.
also replacing metals for use as gas and water drain pipes and has found
a use as artificial leather and readily dyed to bright colours!
Polystyrene is made from
'styrene* (another alkene monomer) and is used in a gas expanded form
for packaging and insulation - 'polystyrene foam' or 'expanded
Polymers have many useful applications and new
uses and new polymers are being developed all the time
There are lots of examples!
- those listed are on many GCSE syllabuses
Many metals have become
quite expensive so things made from plastics derived from oil and
quite cheap at the moment, but prices will rise as cheap oil gets
packaging materials which are light and stretchable.
Waterproof coatings for fabrics
Dental polymers for
Wound dressings made
from hydrogels - polymers that hold water and keep wounds moist.
materials (including shape memory polymers)
eg 'memory foam' is a polymer that gets softer when it gets warmer
so you can make a mattress which adopts your body shape for
Elastic fibres that are
very stretchable to make tight fitting clothing eg Lycra fibres for
tights and sports clothing.
Many polymers are not biodegradable, so they are
not broken down by microbes and this can lead to
problems with waste disposal - see section 7c below.
Because of lack of
biodegradability, you get environmental problems with landfill sites and
street litter and it may take years before the plastic materials
break down - ie decompose!
However, all is not lost and
chemistry and technology can come to the 'rescue' and lots of new
improved polymers for existing applications as well as new polymers
for new applications are constantly being developed.
eg plastic bags are being made from polymers
derived from cornstarch making biodegradable plastics that break down more easily
via microorganisms in the environment.
AND, wherever possible,
recycle and reuse! (see section below).
Extra little note on natural
Starch and cellulose are
natural polymers but are not used as 'material polymers' commercially.
DNA is actually a polymer,
but of rather a delicate constitution!
Rubber has been used for
centuries as a natural elastic polymer, but it has been replaced by
synthetic polymers like neoprene.
Silk has been used as a
clothing and decorative fabric for thousands of years, and, like sheeps
wool, is essentially a protein polymer material. Synthetic man-made
polymers like nylon and terylene where developed and designed to try and
mimic its useful clothing properties, though nylon's excellent
properties eg strength have meant it has found many and diverse
with using and disposing of Polymers or Plastics
Polymers or plastics cannot be easily broken down by
micro-organisms i.e. most, at the moment, most are NOT biodegradable
which leads to
waste disposal and other environmental problems eg
'Non-rotting' litter around the environment.
Land-fill sites are getting full
and recycling isn't as easy as it may seem. (see 3.below)
using waste plastic as fuel must be very efficient to avoid any other
pollution problem. (see 2.)
Even our lakes, seas and
oceans are carrying waste plastic materials causing harmful effects on
Can we burn waste plastic?
When plastic materials burn they can
produce highly toxic gases such as carbon monoxide, hydrogen cyanide and
hydrogen chloride (particularly from PVC and other plastics containing
chlorine and nitrogen).
The toxic fumes cause deaths in house fires and controversial problems with alleged inefficient waste incinerators as they will
definitely cause environmental problems if burned on waste tips!
can we recycle plastics? What ways are used to recycle plastics?
to recycle plastics because of separation into the various
types of polymer and their different physical properties. BUT this should not prevent us from trying
and it would be beneficial to prolong the life of the finite crude
oil reserves AND reduce pollution and space in land-fill sites.
There are problems in trying
to sort out the different plastics into useful categories, they are not
easy separate, you can't just use any old mixture of polymers.
people are coming up with ideas. A company in Scarborough, England, is
collecting waste plastic. This is shredded and compressed into porous
pads and used for good 'underground' drainage layers for footpaths, golf
greens and sand bunkers etc. and has a good working life because the
material isn't biodegradable!
Clear soft drink bottles are
made from PET (polyethene/polyethylene terephthalate) which can be
recycled as fibre-fill for pillows and carpets.
This save 90% of the energy
costs compared to the original manufacturing process.
Energy costs are a big
economic recycling factor, its not just about making naturally occurring
resources like oil last longer.
However, it takes about
20,000 drinks bottles to make a tonne of recycled PET.
are being developed which are more biodegradable
or can be recycled, so will the
paper bag and cardboard package make a comeback? (in Ireland you have to
bring your own bag or buy one, and not necessarily a plastic one!), this
isn't a recycling process BUT it does reduce environmental pollution..
In 1988 Australia issued
bank notes made from recycled poly(propene). These plastic notes
apparently have the advantage of being more difficult to forge and they
Other ideas include making
more durable plastic bags that can be used many times for shopping.
Ideally some recycled
thermoplastics and scrap material from a plastic product manufacturing
process, can be heated and remoulded in the same process or another
It is possible in
some cases to break the plastic material down with heat (a sort of
'cracking') into smaller organic hydrocarbon molecules that can act as
chemical feedstock like oil, from which you can make other valuable
products including plastics.
Less green, but useful
purpose, is to use scrap plastic as a fuel, but complete incineration is
not always easy to be efficient.
All of these will slow down
the rate at which valuable oil-petroleum deposits are depleted - the
latter are finite, so we should make the best use of them.
section 4. Pollution
Carbon monoxide etc.
Multiple Choice Quizzes and Worksheets
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products
KS4 Science GCSE/IGCSE m/c QUIZ on other aspects of Organic Chemistry
3 linked easy Oil Products gap-fill quiz worksheets
ALSO gap-fill ('word-fill') exercises
originally written for ...
... AQA GCSE Science
Useful products from
crude oil AND
... OCR 21st C GCSE Science
Worksheet gap-fill C1.1c Air
pollutants etc ...
... Edexcel 360 GCSE Science
Crude Oil and its Fractional distillation
... each set are interlinked,
so clicking on one of the above leads to a sequence of several quizzes
Level Organic Chemistry revision notes
Notes information to help revise KS4 Science
Additional Science Triple Award Separate Sciences GCSE/IGCSE/O level
Chemistry Revision-Information Study Notes for revising for AQA GCSE Science, Edexcel
GCSE Science/IGCSE Chemistry & OCR 21st Century Science, OCR Gateway Science WJEC/CBAC
GCSE science-chemistry CCEA/CEA GCSE science-chemistry
(and courses equal to US grades 8, 9, 10)
content copyright © Dr W P Brown 2000-2013 All rights reserved
revision notes, puzzles, quizzes, worksheets, x-words etc. * Copying of website
material is not permitted
Alphabetical Index for Science
B C D
G H I J K L M
N O P
U V W
X Y Z