Uses of polymers
Different polymerA large molecule formed from many identical smaller molecules known as monomers. have different properties, so they have different uses. The table gives some examples:
| Polymer | Use | Property of polymer |
| Poly(ethene) | Plastic bags | Low density, waterproof |
| Poly(propene) | Ropes | Strong, colourful |
| Poly(tetrafluoroethene) 鈥 PTFE | Coating for frying pans | Non-stick |
| Poly(chloroethene) 鈥 PVC | Water pipes | Low density, does not corrode |
| Polymer | Poly(ethene) |
|---|---|
| Use | Plastic bags |
| Property of polymer | Low density, waterproof |
| Polymer | Poly(propene) |
|---|---|
| Use | Ropes |
| Property of polymer | Strong, colourful |
| Polymer | Poly(tetrafluoroethene) 鈥 PTFE |
|---|---|
| Use | Coating for frying pans |
| Property of polymer | Non-stick |
| Polymer | Poly(chloroethene) 鈥 PVC |
|---|---|
| Use | Water pipes |
| Property of polymer | Low density, does not corrode |
Polymers have properties that depend on the chemicals they are made from and the conditions in which they are made.
For example, there are two main types of poly(ethene) 鈥 LDPE, low-density poly(ethene), and HDPE, high-density poly(ethene). LDPE is weaker than HDPE and becomes softer at lower temperatures.
Modern polymers are very useful. For instance, they can be used as:
- new packaging materials
- waterproof coatings for fabrics (eg for outdoor clothing)
- fillings for teeth
- dressings for cuts
- hydrogels (eg for soft contact lenses and disposable nappy liners)
- smart materials (eg shape memory polymers for shrink-wrap packaging)
This table summarises some of the advantages of using polymers over traditional materials.
| Object | Traditional material | Polymer used | Advantage |
| Guttering | Iron | PVC | Does not corrode, low density |
| Shopping bags | Paper | Poly(ethene) | Waterproof, strong |
| Drinking cups | Glass/china | Polystyrene | Does not smash, heat insulator |
| Object | Guttering |
|---|---|
| Traditional material | Iron |
| Polymer used | PVC |
| Advantage | Does not corrode, low density |
| Object | Shopping bags |
|---|---|
| Traditional material | Paper |
| Polymer used | Poly(ethene) |
| Advantage | Waterproof, strong |
| Object | Drinking cups |
|---|---|
| Traditional material | Glass/china |
| Polymer used | Polystyrene |
| Advantage | Does not smash, heat insulator |
Environmental issues with polymers
Most polymers are very unreactive and are non-biodegradable, ie they do not rot because microbes cannot break them down.
If polymers are put in normal household waste, they are then taken to landfill and buried, where they will remain for hundreds of years.
Burning plastics as fuel is not a good solution either, as this leads to the release of carbon dioxide (contributing to the greenhouse effect) as well as various toxic gases.
To deal with this problem, most plastics can be recycled. Recycling plastics has a number of benefits.
- Less plastic goes to landfill, reducing pollution and making current landfill sites last longer.
- Less crude oil is needed to produce new plastics. This conserves crude oil which is a finite resource that will eventually run out.
- Recycling plastic requires less energy than making new plastic. This lowers costs and reduces greenhouse gas emissions.