Pyrolysis is the
degradation of complex
materials caused by
heat, in a low
oxygen,
inert atmosphere or a
vacuum.
Molecules cleave at their weakest points to produce smaller,
volatile fragments called pyrolysate. This process differs from
combustion, but can occur near to the site of combustion, when the oxygen has been used up by the
fire.
From the
Greek pyr, meaning fire, and
lysis meaning
loosing or 'to
split'.