National Chemistry

 

 

Polymers

 

1. Most plastics and synthetic (man-made) fibres are made from oil

    Properties   -  easy clean - hygienic;  light;  durable;  electrical insulator; easily coloured; last a long tome (are not biodegardable)

 

 

Natural      - expensive, wear out, but biodegradable and made from renewable sources

Man-made - made from finite resource (oil) - not biodegradable but cheap and long lasting.

 

Problems:

some plastics burn or smoulder giving off poisonous fumes.

not biodegradable

 

2 Thermosetting plastics cannot be reshaped by heating and melting - used for items which  get hot - plugs, switches, electrical appliances.  (They are set)

Thermoplastic plastics can be melted or reshaped.

 

3 Plastics are polymers - very large molecules made from a small molecule called a    monomer-

 Many monomers are unsaturated hydrocarbons - aIkenes (with C=C) -    produced by cracking longer chain aIkenes.  Monomers form polymers by addition polymerisation.

Addition polymerisation

 

ethene produces polythene ;  

                               monomer                                           polymer

                  H   H            H  H          H  H                       H  H  H  H  H  H  H

 

                  C=C            C=C         C=C      ------>       -C-C- C- C-C-C-C -

 

                 H   H            H  H          H  H                        H  H  H  H  H  H  H

 

                                  ethene                                          polythene

 

 Alkene monomers react by addition (breaking one of the bonds in the C=C) to polymerise

 

 

One bond of the double bond breaks open allowing each unsaturated monomer to make a

 connecting bond. (watch)

repeating unit

 

 

CONDENSATION POLYMERISATION

In this style of polymerisation the monomers join together and produce a water molecule. Polyesters are formed in this manner.  The boxes represent a combination of atoms – this can vary quite widely. The atoms in the box are of no particular interest – just copy exactly if you need to.

                                       

National 4 and 5

Polymers

 

These notes are for the Scottish National Chemistry course taught in fourth year in most Scottish schools.

 

The notes available here are concise notes. They are NOT to be considered as material to learn from - they are for revision.

 

 The notes are arranged under the following topics

 

National 3          Unit 1

                          Unit 2

                          Unit 3

 

National 4 and 5  Unit 1            Rates of Reaction

                                                  Atomic Structure

                                                  Bonding and Properties

                                                  Acids and bases

 

National 4 and 5  Unit 2       Fuels and Homologous Series

                                                Consumer Products

                                                Carbohydrates

 

National 4 and 5  Unit 3         Metals

                                                   Plastics

                                                   Fertilisers

                                                   Nuclear Chemistry

                                                  Chemical analysis

 

 

 

 

 

 

 

 

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