Chemistry AQA C1b

Polymers are very large molecules made from many small   monomers

eg. ethene molecules join together in long chains to form Poly(ethene)  This is ADDITION POLYMERISATION

 Other alkenes can be reacted together in a similar way to form polymers such as Poly (propene)                                                              Many plastics we use as bags, bottles, containers or toys are made from alkenes                 

Polymers have very long molecules that form a tangled mass this is what gives them strength and flexibility.

Thermosoftening : have weak intermolecular forces - so when they are heated they become soft and when they cool they harden. They can be heated and moulded into shapes and can also be remoulded by heating again. Used where flexibility is needed and where there is less exposure to heat.

Thermosetting : When they are heated for the first time, chemical bonds form between polymer molecules which link together. These strong bonds make the plastic set hard and the plastic cannot be softened again by heating. Are more rigid and can withstand more heat