THERMAL-DECOMPOSITION OF ARYL ALICYCLIC POLYIMIDES STUDIED BY THERMOGRAVIMETRY MASS-SPECTROMETRY AND PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY

The thermal decomposition of four aryl-alicyclic polyimides was studied by thermogravimetry/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry. The effect of the structure of aliphatic segments on the thermal stability and decomposition mechanism of polyimides is discussed. The thermal stability is highly affected by the ring strain of the aliphatic cycles, but the chemical structure of aliphatic units has only a minor effect on the decomposition temperature of aromatic segments. However, the yield of pyrolysis products of both aromatic and aliphatic origin is substantially affected by the structure of aliphatic segments, showing that the primary decomposition of alicycles plays a key role in the decomposition mechanism. The fast pyrolysis and thermogravimetric analysis result in different product yields. However, in both cases the charring process is influenced by the hydrogen-content of the samples indicating the importance of hydrogen-transfer processes.