Poly (ether ether ketone)(PEEK) was synthesized via polycondensation of hydroquinone with 4, 4'-difluorobenzophenone at 320℃ for 5 h.Thermal and thermo-oxidative degradation of PEEK was studied over a wide range of temperatures.In an inert medium, decomposition of the polymer occurred in one stage, with the formation of a coke residue accounting for approximately 50% of the original polymer mass.In air, the mass loss curve exhibited two distinct stages.The first stage involved breakdown of the main polymer chain, the speed of which indicated a radical chain failure mechanism.In the second stage, the rate of mass loss clearly decreased, indicating a transition from the radical chain failure mechanism to simple combustion reactions (wherein the polymer combusted completely).To further investigate the nature of the processes occurring during the pyrolysis of PEEK, the investigations were carried out using gas chromatograph under isothermal conditions.It was concluded that during thermal degradation, the decomposition of the polymer starts with the rupture of ketone and ether bonds and proceeds to destruction of the benzene ring at higher temperatures, which is accompanied by the formation of H2O and CH4.Above 500℃, the polymer degradation further involved thermohydrolysis.The thermo-oxidation of PEEK, which was accompanied mainly by the formation of CO2 and H2, was noticeable beginning at 325℃.The total yield of the latter indicated oxidation of fragments of the benzene ring.
