Thermal degradation of syndiotactic polypropylene and the influence of stereoregularity on the thermal degradation behaviour by in situ FTIR spectroscopy

The thermal degradation of syndiotactic polypropylene (sPP) and the influence of stereoregularity on the thermal degradation behaviour have been studied by in situ Fourier transform infrared (FTIR) spectroscopy. With the aid of the time-resolved FTIR, the conventional kinetic parameters, such as the degradation activation energy ΔE and the degradation factor n, can be calculated. The experimental results show that sPP decomposes by random chain scissions. More importantly, the difference of degradation activation energy from some characteristic absorption bands shows that the thermal degradation of sPP is a multi-step process, which is further confirmed by the principal components analysis (PCA). Comparing with isotactic polypropylene (iPP), the main chain of sPP is more flexible, therefore the thermal stability of sPP is much higher than iPP.