High‐resolution thermogravimetry of polyethersulfone chips in four atmospheres

Abstract

Thermal degradation and kinetics of polyethersulfone (PES) chips were studied in air, nitrogen, helium, and argon from room temperature to 790°C by highresolution thermogravimetry (TG) at a variable heating rate in response to changes in the sample's degradation rate. In the four atmospheres, a two-step degradation process in air, argon, and helium or a three-step degradation process in nitrogen of the PES were found in this investigation. In particular, the three-step degradation process in nitrogen of the PES revealed by the high-resolution TG was hardly ever observed by a traditional TG. The initial thermal degradation temperature of the PES increases with the testing atmosphere in the following order: air Ͻ argon Ͻ helium Ͻ nitrogen but the activation energy of the first major degradation of PES increases in a different order: argon Ͻ nitrogen Ͻ helium Ͻ air. The degradation temperature, the temperature at the maximum weight-loss rate, the maximum weight-loss rate [(d␣/dT) m1 and (d␣/dT) m2 ], char yield at 790°C, and activation energy of the first major degradation process obtained by the high-resolution TG were compared with those by traditional TG. The PES exhibits the largest (d␣/dT) m1 and the greatest char yield at 790°C in helium but the largest (d␣/dT) m2 and smallest char yield in air. A significant dependency of the thermal decomposition of the polymers on the physicochemical properties (density, thermal conductivity, and oxidative ability) of the testing atmospheres is elaborated for the first time.

Highly permeable and mechanically robust silicon carbide hollow fiber membranes

“…A second mass loss step is recorded at intermediate temperatures (450-650 1C), where SO 2 , CO, CO 2 and water are the main gases emitted, followed by a minor mass loss concurring with release of methane, CO and CO 2 at 750 1C. This observed decomposition process matches closely to the reported decomposition of PES under an argon atmosphere[27][28][29]Photo of, from left to right, a green, sintered at 1500 1C, sintered at 1790 1C, sintered fiber 2075 1C (A), and cross-sectional images of a green (B), a green (C), 1500-Ar (D), 1790-Ar (E) and 2075-Ar (F) sintered fibers.…”

Effects of sintering atmospheres on properties of stainless steel porous hollow fiber membranes

“…We did not detect H 2 S (m/z¼34) during the temperature range from 30 1C to 800 1C, indicating the element S could still stay in the organic fragments. It was documented that the remaining organic fragments with phenyl structure in hollow fibers could be stable until 800 1C and then converted to carbon at elevated temperature [23,24]. The residual carbon could be also consumed by hydrogenation at high temperature (4900 1C) [25][26][27][28][29], describing as CþχH-CHχ.…”

Synthesis and Characterization of Novel Ion‐Conducting Membranes Based on Poly(ether sulfone) and Protic Ionic Liquid

“…Two main thermal degradation events can be observed in all samples, which represent different behaviors according to the addition of zirconia and ionic liquid. For the neat PES membrane, considering a weight loss about 17% for the first main event, not only confined NMP molecules (boiling point around 200 °C) but sulfone groups (lower dissociation energy of the C‐S bond) can be thermally degraded between 150 and 300 °C too. Then, the next thermal degradation process from 450 to 600 °C (weight loss around 45%) can be attributed to the aromatic ring degradation of polymer backbone.…”