1. Polymerisation
IIC 2012

2. Objectives Recall the many different uses and applications of polymers
Describe how a polymer is made from monomers and the use of plasticizers.
Explain the problems that are caused by plasticizers used in polymer manufacture

3. Recap - Alkenes
Alkenes are hydrocarbons with double bonds between carbon atoms.
One double bond is enough, it does not need to be between every carbon atom.
Examples are ETHENE and PROPENE

4. The general formula
CnH2n

5. Using the formula Use this to calculate the formula for an alkene with
10 carbon atoms
15 carbon atoms
14 carbon atoms

6. Using the formula - answers
Use this to calculate the formula for an alkene with
10 carbon atoms C10H20
15 carbon atoms C15H30
14 carbon atoms C14H28

7. Polymerisation

8. Polymerisation
In polymerisation many small molecules MONOMERS join together to form a larger molecule POLYMER sometimes containing many thousands of monomers.

9. Names of polymers How many polymers can you name?
Write the list in your book.

10. Did you get? Add to your own list
Cling film/cellophane
Non stick coating (Teflon)
Tights and clothing (Nylon, Lycra)
Windows and doors (uPVC)
Bottles and food packaging
Waterproof coatings for fabrics (Goretex)
Dental polymers
Wound dressings especially for burns
Hydrogels for use in nappies.
Smart materials such as memory foam.
PVC poly vinyl chloride

11. Drawing monomers and polymers

12. Polymerisation of PVC
Can you draw the ‘H diagram’ for PVC from the monomer vinyl chloride?

13. Answer

14. Properties of PVC
PVC is a rigid hard waterproof plastic that is commonly used for applications where durability is required eg “windows, doors and conservatories”.

15. Rigid or flexible
It is not always desirable for the plastic to be rigid and brittle.
Toys in particular need to be safe and to maintain their appearance and for this they need to be flexible.

16. Plasticizers
Plasticizers for plastics are additives, most commonly phthalate ester.
Almost 90% of the market for plasticizer is for PVC, giving this material improved flexibility and durability.

17. How do plasticizers work?
Plasticizers work by embedding themselves between the chains of polymers, spacing them apart (increasing the "free volume"), and making it softer.
For plastics such as PVC, the more plasticizer added, the more flexible and durable it will be.

18. Plasticizer between chains of polymer

19. Problems with plasticizers
Plasticizers evaporate and tend to concentrate in an enclosed space; the "new car smell" is caused mostly by plasticizers evaporating from the car interior.
Phthalates have been linked with potential health problems.
When the plasticizer has evaporated the plastics become brittle and less durable.
Other possible sources of the problem:

20. Plenary - Questions
We are going to move onto some questions now