The thermal degradation properties of polymethacrylonitrile (PMAN) hav
e been studied by isothermal heating and thermogravimetric analysis. T
here are two initiation processes for weight loss from PMAN degraded i
n nitrogen, namely chain-end and random scission initiation. There is
also an internal cyclization reaction which forms a thermally stable r
esidue during the thermal degradation process. The activation energies
of the weight loss and formation of stable residues have been calcula
ted. X-ray photoelectron spectroscopy has been used to investigate the
structure of the stable residue and thus to confirm the degradation m
echanism.