Effects of Molecular Weight on Thermal Degradation of Poly(α-methyl styrene) in Nitrogen

Abstract

The effects of molecular weight on the thermal degradation behavior of poly(α-methyl styrene) (PAMS) was investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The Py-GC/MS analysis results showed that the degradation of PAMS with different molecular weights in nitrogen produced only the monomer, alpha-methylstyrene. The TGA results showed a pronounced reduction in the decomposition temperature with increasing molecular weight. The degradation kinetic parameters, calculated by the Kissinger and the Coats–Redfern methods, further revealed that the activation energy and the pre-exponential factor decreased with increasing molecular weight. Most importantly, the degradation order of the PAMS in nitrogen remained around 1, independent of the molecular weight, suggesting the maintenance of the depolymerization mechanism. All the above results provided an insight into the effects of molecular weight on the thermal degradation behavior of PAMS.

Keywords:

• degradation kinetic
• inertial confinement fusion
• molecular weight
• poly(α-methyl styrene)

Funding

The financial support from the National High Technology Development Project Foundation of China and the China Academy of Engineering Physics (2014B0302052) is gratefully acknowledged.