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9.5 Option – Polymers: 2. Uses and properties of synthetic polymers| Syllabus
reference (October 2002 version) |
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| 2. Synthetic polymers have different
uses based on their different properties |
Students learn to:
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Students:
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Extract from Senior Science Stage 6
Syllabus (Amended October 2002). © Board of Studies, NSW
[Edit: 16 Sept 08]
Prior learning: Science Stages 4–5
Syllabus 4.11.1a and 4.11.1b, 5.7.3d, 5.11.1.
Background information: Scientists
have developed synthetic materials to replace and complement the existing range
of natural polymers. These synthetic materials (like natural materials) have
advantages and disadvantages. The raw material for these fibres comes mainly
from petrochemicals.
choose
equipment or resources to perform
a first-hand investigation to make playdough and slime as an example of a natural
and a synthetic polymer.
- Find a recipe for playdough and for slime. You could use the ones below or talk to your local pre-school or infants department of the local primary school. You could look on the Internet for a slime recipe.
- Choose the mixing equipment you will need as well as the ingredients. You may need a storage container for playdough, depending on what you’re going to do with it.
- Place in a mixing bowl, half a cup of salt, one cup of plain flour and 2 tablespoons of “cream of tartar” (potassium hydrogen tartrate).
- Add one cup of hot water and one tablespoon of edible oil. (Food colouring may be added)
- Mix ingredients well.
- Knead the dough on a level surface until dough is even.
- Store in an air-tight container to extend its shelf life.
Playdough recipe - Playdough is a natural polymer.
Slime recipe - Slime is a synthetic polymer.
- Place 200 mL of warm distilled water into a container.
- Add borax (sodium tetraborate, Na2B4O7 10H2O) one teaspoon at a time, stirring after each addition, until a saturated solution is formed.
- In a separate container place 60 mL of PVA (wood) glue
- Add two drops of glycerine, two drops of food colouring and a teaspoon of moisturising cream to the PVA glue and mix thoroughly.
- Pour 60 mL of saturated borax solution (made earlier) to the PVA glue mixture
- Stir the mixture until it has a “stringy” consistency.
- Add a further 120 mL of borax solution and stir until “slime” is formed.
- Test the slime for its properties.
gather, process and present information from secondary sources on more specialised polymers, such as Kevlar or spectra fibres and relate its properties to its uses in society
- Gather the information from secondary sources including text-books, magazines, encyclopaedias, CD –ROMs, Internet websites and newspapers, among others.
A website that has information on aramid, the polymer that kevlar is a
brand name of, is Wikipedia 
The Free Encyclopedia.
- Process the information by organising it according to the source and then comparing the different sources. Choose the best information and discard any that is superfluous.
Some information that may be useful
Kevlar and spectra are the trade names for a specific fibre made from aromatic polyamide (aramid).
Kevlar is lightweight but very strong, ultra violet and heat resistant.
Kevlar can be used to make protective clothing, strong ropes, sailcloth and sheets for construction use.
- Present your information in a suitable form such as a table.
gather and process information from secondary sources on the commonplace uses of synthetic polymers such as paints, fabrics and textiles, synthetic rubber, insulating materials, adhesives, nail polish, industrial foams, packaging or bullet-proof vests.
- Gather information from the Internet, or by obtaining information
from some companies that produce these products. One website is How
Products are Made, Volume 1 . Type in whichever product you want to investigate,
then scroll down to find the information you want.
- You don’t have to gather information on all these products but it would be best to choose a range of products. As you gather the information process it by putting it in a table. A suggested table could be:
Polymer
Use
Fabric-Nylon
Pantihose, rope
Polyester
Shirts
Adhesives-PVA glue
Glues many materials such as wood to wood.
- Comment on the wide range of uses of synthetic polymers and their importance to our everyday lives.
describe
some synthetic polymers including
- polyamides (nylons)
- polyester
- polyethylene
- polystyrene
- PVA
- PVC
- Lycra and discuss,
using examples from each group, how their properties are related to the use
made of them by society
- There are many synthetic polymers, all made from crude oil. Many are used to make fabrics, containers and other objects. The properties of these polymers will affect the use to which they are put.
Nylons (polyamides) are co-polymers, that is, made from two different monomers.
- Varying the co-polymers can vary the properties of polyamides.
- Nylon is hard-wearing, strong, elastic and dries quickly after washing.
- Nylon can be an uncomfortable fabric to wear, especially in summer when it may stick to your body due to it retaining static electricity.
- Nylon is used to make a variety of clothing, including pantihose (elasticity) as well as carpets, ropes and parachutes (strength and hard-wearing).
Polyesters consist basically of repeated units of an ester.
- Dacron is a polyester, also known as “terylene”.
- Polyesters have similar properties to nylon and hence are often used in clothing.
- Polyesters are often blended with organic fibres eg cotton.
- Polythene has two forms, low density and high density.
- Low density polythene is easily melted and shaped. It is used for bags, wrappers and flexible bottles.
- High density polythene is more rigid and has a higher
melting point. It is used for making hobby boxes etc.
Polystyrene is rigid with good heat and electrical insulating properties.
- It is brittle but cheap.
- Polystyrene is used in moulded products and foams
(expanded polystyrene), e.g. plastic toys and portable coolers.
PVA (polyvinyl acetate)
- It is used to make wood glue and ‘slime’.
- PVA is a thermoplastic vinyl resin, produced from its monomer by emulsion polymerisation.
- PVA has the advantage over the other resinous adhesives in that it is available in the form of an emulsion that is readily diluted with water, is easily applied, and is safe to use because it contains no flammable solvents.
- There is no need to use preservatives or fungicides
because it does not deteriorate quickly and is unaffected by mould or fungi.
PVC
- stands for polyvinyl chloride.
- PVC is strong and can be moulded. It can be used to
make plastic pipe and wire insulation.
Lycra
- is the trade name for a type of “spandex”- an elasticised material made chiefly of polyurethane.
- Lycra feels comfortable, resists abrasion and stretches and retains shape well.
- Lycra is used in swimwear, hosiery and any clothing where elasticity is a major consideration.
identify that many of the chemicals used in the production of polymers are extracted from coal, petroleum and natural gas
- Coal, petroleum and natural gas contain hydrocarbons – compounds containing carbon and hydrogen.
- Petrochemicals are chemicals obtained from natural gas or petroleum. They are the sources of many monomers. Coal is a minor source of monomers.
discuss the implications for the future of the production of polymers from petrochemicals.
- Petrochemicals are non-renewable resources, that is once they are used up no more will be made.
- Estimates vary, but there is thought to be enough coal reserves for about 300 years at current rates of use.
- It is anticipated that oil and gas will run out before the end of the 21st century.
- As petrochemicals become scarcer, costs will rise so it will be profitable for alternative materials to be found.
- In order to conserve the supplies of petrochemicals it is important to recycle polymers.
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