Influence of water vapor in NO2 gas on the degradation behaviors of polyphenylene sulfide non-woven bag-filters at high temperatures

The emission of particulate matter from industrial plants can lead to significant health issues. Considering the polyphenylene sulfide (PPS) filter medium as a promising collector, the effects of water vapor on the degradation behavior of PPS are investigated in NO2 gas under high-temperature (140 and 200 °C) conditions. Upon exposure to NO2 without water vapor, the fiber surface underwent more severe morphological degradation at 200 °C than at 140 °C, whereas the tensile strength of the filter was consistently lower at 140 °C. The presence of water vapor in the NO2 gas at 200 °C induced fiber swelling, and significantly accelerated tensile strength reduction and oxidation of the fiber surface and the whole fiber, but almost not at 140 °C. These conditions also promoted benzene ring oxidation, including substitution with hydroxyl and carboxyl groups, which enhanced the hydrophilicity and moisture absorbability of the fiber. Although oxidation proceeded uniformly and homogeneously throughout the fiber at 140 °C, it proceeded sequentially from the fiber surface as a diffusion-controlled reaction at 200 °C. Furthermore, while the progression of the fiber surface oxidation seems to determine morphological damage on the fiber surface, the progression throughout the whole fiber may decide the decrease in tensile strength. These results indicate that the existence of water vapor in NO2 gas promotes the mechanical and chemical degradation of the PPS filter medium at 200 °C, although at 140 °C, its presence had little effect on the evaluated items. • The PPS oxidation product depended on the temperature and presence of water vapor. • Exposure to NO 2 with water vapor at 200 ℃ greatly reduced the PPS tensile strength. • The strength of the PPS filter depended on the oxidation degree of its whole fibers. • The extent of PPS fiber surface damage was defined by the degree of surface oxidation. • The oxidation of PPS proceeded uniformly at 140 ℃ and unevenly at 200 ℃.