Formulae of common polymers

Hydrocarbons obtained from fossil fuels are broken down into simpler molecules in the "cracking process". The cracking process involves heating a hydrocarbon in the presence of a catalyst which causes it to break down into simpler molecules such as ethylene (ethene) C2H4, propylene (propene) C3H6, and butene C4H8. 

A single unit of a molecule like ethene is called a monomer.

Polymers are created by linking lots of units of a monomer in a long chain in a process called polymerisation. 

Single units (monomers) of the more common polymers are shown below.
     
Formula for polyethylene (PE)
Formula for polyvinyl chloride (PVC)
Formula for PTFE
Polyethylene (PE) monomer
Polyvinyl Chloride (PVC) monomer
Polytetrafluoroethylene (PTFE) monomer
   

 

Formula for Polyethylene (PE)
Polyethylene (PE) polymer

Formula for polyvinyl chloride (PVC)
Polyvinyle chloride (PVC) polymer

The PVC polymer formula is similar to the PE polymer formula but you will notice
that one hydrogen atom is replaced by a chlorine atom in each PVC monomer.
     
Formula for polystyrene (PS)
Polystyrene (PS) monomer
Polypropylene (PP) monomer
Polymethyl methacrylate (PMMA) monomer
     

The formula for polystyrene (shown above) includes a hexagon with a circle inside.

The hexagonal symbol represents the compound benzene, C6H6.

Benzene ( C6H6 )
   

The formula for a single unit of polymethyl methacrylate (PMMA) is C5O2H8. This can be shown as in the diagram above left, or simplified as in the diagram above right.