An XPS investigation of thermal degradation and charring processes for PVC and PVC/Cu_2O systems in the condensed phase—Ⅱ

摘要

Experimental evidence convincingly shows that the combination of XPS and TGA/FTIR enables the provision of significantly more information on degradation and charring of polymers upon heating, which are central to flame retardance and smoke emission of polymers. PVC and PVC/Cu_2O were chosen as systems to be investigated. Qualitative and quantitative information concerning these two processes in the condensed phase indicates that early crosslinking plays a most important role, in particular, in the presence of catalyst Cu_2O during degradation and charring processes. The interaction between PVC and Cu_2O has been experimentally confirmed with the help of the shake-up satellites and Auger parameter α~*, showing that the redox cycle of the catalyst itself works quite well: Cu_2~IO → Cu~ICl → Cu~0 → Cu_2~IO as the temperature rises from ambient to 500℃, which is in complete agreement with the reductive-coupling mechanism. The valence band structures also turn out to be quite informative in the elucidation of both processes.