Thermal degradation of blends of polystyrene and poly-4-methoxystyrene with bisphenol A polycarbonate

Blends of polystyrene (PS) and poly-4-methoxystyrene (PMeS) with bisphenol A polycarbonate (PC) (1:1 by weight) have been studied using thermogravimetry (TG) and thermal volatilisation analysis (TVA). The condensable volatile products obtained in the TVA experiments were separated by subambient TVA and the less-volatile liquids were examined by GC-MS. The cold ring fraction of products was characterised by IR spectroscopy.

On degradation, both PS-PC and PMeS-PC blends show an interaction which is observed as a destabilisation. It is suggested that in the degrading blends, the PC component is destabilised as a result of transport of small radical species from the other polymer phase. These radicals may abstract hydrogen atoms, leading to an increase in backbone scission reactions and consequently a lower degradation temperature than when the polymer is degraded alone.