Thermal degradation study of some poly(arylene ether nitrile)s by TG/MS/FTIR analysis

Abstract A study on thermal and thermo-oxidative stability, i.e. the degradation mechanism for a series of poly(arylene ether nitrile)s was performed by applying simultaneous mass spectrometry and Fourier transform infrared spectroscopy of gas products from a thermogravimetric analyzer into two working atmospheres, air and helium. The polymers were prepared by nucleophilic aromatic substitution of 2,6-dichlorobenzonitrile with phenolphthalein, 2,2-bis(4-hydroxyphenyl)propane and 2,5-bis(4-hydroxyphenyl)-1,3,4-oxadiazole. A poly(arylene ether nitrile) was prepared by cyclopolycondensation reaction, in two steps, starting from 4,4′-oxydiphthalic anhydride and 2,6-bis(3-aminophenoxy)benzonitrile. The influence of benzonitrile units, isopropylidene linkages, phthalide groups, oxadiazole or imide rings on the thermal degradation behavior was discussed in detail. The onset mechanism of the thermal degradation process in the two working atmospheres was similar. The major identified products in the decomposition gases were carbon dioxide, water, carbon monoxide, benzene, phenol and benzonitrile. In addition, nitrogen monoxide was observed in the case of polymers containing oxadiazole or imide rings.