The effect of ammonium polyphosphate (APP) on thermal and thermo-oxida
tive degradation of polystyrene (PS) was studied with methods of Therm
ogravimetry (TG), Gas Chromatography/Mass Spectrometry (GC/MS), Thermo
chromatography (ThGC), Size Exclusion Chromatography (SEC), and Fourie
r Transform Infrared Spectra (IR). APP slightly accelerated thermal de
gradation of PS in nitrogen due to its acidity. However, whether APP a
ccelerated or retarded thermo-oxidative degradation of PS much depende
d on addition levels in air. At the low addition levels, APP seemed to
retard thermal degradation of PS via formation of a glassy layer; at
the high addition levels, APP seemed to accelerate thermal degradation
of PS due to its acidity.