Abstract
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