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Polymerisation

Polymerisation. IIC 2012. 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. Recap - Alkenes.

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Polymerisation

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  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 monomer monomer polymer polymer

  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. http://news.bbc.co.uk/1/hi/8361863.stm • http://www.youtube.com/watch?v=gKv1LDZSzPk • When the plasticizer has evaporated the plastics become brittle and less durable. • Other possible sources of the problem: http://www.dailymail.co.uk/health/article-105466/Fertility-timebomb-drinking-water.html

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

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