Polystyrene (PS) is extensively used as food packaging material
mainly in the form of GPPS (general purpose polystyrene), HIPS
(high impact polystyrene) and EPS (expanded polystyrene) or in
copolymerisation with other monomers, especially acrylonitrile
and butadiene. Due to the production process styrene monomer
(S) is found in residual amounts in such polymer food containers,
due either from unreacted S in the starting polymer before
converting or from thermal depolymerisation during the
converting process.