====== Expanding monomers ======

During polymerisation (the process in which 'monomers' crosslink chemical bonds to become 'polymers') //most// chemical substances physically contract in volume. This effect can cause problems in plastic moulding processes.

Over the years, however, a number of chemical monomers have been discovered which //expand// as they polymerise (typically by around 10-15%) - they are therefore added to the plastic moulding mixes so as to stabilise the moulding process.

The expanding monomers are mainly based on 'cyclic' compounds (atomically structured as a ring) and it has been found that the larger the ring, the larger the expansion. The complex atomic mechanisms which drive the expansion are not known.

See [[https://en.wikipedia.org/wiki/Expanding_monomer#Concept_of_expanding_monomers|Wikipedia]]