polymers

polymers

1. Alkenes can be used to make polymers. Polymers are very large molecules made when many smaller molecules join together, end-to-end. The smaller molecules are called monomers.

2. The animation shows how several chloroethene monomers can join end-to-end to make poly(chloroethene), which is also called PVC.

3. Ethene can polymerise to form poly(ethene), which is also called polythene.

4. Propene can polymerise to form poly(propene), which is also called polypropylene.

5. Different polymers have different properties, so they have different uses. The table below gives some examples.

6. One of the useful properties of polymers is that they are unreactive, so they are suitable for storing food and chemicals safely. Unfortunately, this property makes it difficult to dispose of polymers.

7. Most polymers, including poly(ethene) and poly(propene) are not biodegradable.

8. This means that microorganisms cannot break them down, so they may last for many years in rubbish dumps.

9. However, it is possible to include chemicals that cause the polymer to break down more quickly.

10. Carrier bags and refuse bags made from such degradable polymers are already available.

11. Polymers can be burnt or incinerated. They release a lot of heat energy when they burn and this can be used to heat homes or to generate electricity.

12. There are problems with incineration. Carbon dioxide is produced, which adds to global warming.

13. Toxic gases are produced unless the polymers are incinerated at high temperatures.