High‐resolution thermogravimetry of polyphenylene sulfide film under four atmospheres

Thermal degradation of polyphenylene sulfide (PPS) film was investigated in air, nitrogen, helium, and argon with different physical and reactive characteristics from room temperature to 790°C by a high‐resolution thermogravimetry (TG) at a variable heating rate in response to the changes in the sample's weight‐loss rate. In nitrogen and argon, only a single‐step degradation process of the PPS was observed, but in helium, a two‐step degradation process of PPS was found. Notably, in air a four‐step degradation process of the PPS, which was hardly ever revealed by a traditional TG, was found in this investigation. The initial thermal degradation temperature T d and temperature at the first maximum weight‐loss rate T dm1 of the PPS increased in the following order: in helium < in nitrogen < in argon < in air. The first maximum weight‐loss rate also increased with the variation of atmosphere in the order: nitrogen < air < argon < helium. The char yield at 700°C increased in the order: in air < in helium < in nitrogen < in argon. The activation energy of the major degradation process of PPS calculated based on the high‐resolution TG data was very high, increasing in the order: in nitrogen < in argon < in helium < in air. The thermal decomposition parameters of the PPS determined by the high‐resolution TG were systematically compared with those by traditional TG at a constant heating rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2053–2059, 2002