Effects of exposure temperature on degradation of polyphenylene sulfide non-woven bag-filter media by NO₂ gas at high temperature

The influence of exposure temperature and exposure time on the degradation of polyphenylene sulfide (PPS) fabric filter media was examined in detail. Although increases in the exposure temperature and time resulted in more severe damage, PPS filter media subjected to lower exposure temperatures always had lower tensile strengths than those of media subjected to higher exposure temperatures. Although the elastic modulus increased with exposure time, the hardening rate increased with exposure temperature. Crystallinity increased monotonically with exposure time at higher temperatures, whereas it increased once and then decreased with exposure time at lower temperatures. Exposure at lower temperatures led to the oxidation of S to the sulfinyl group, whereas exposure at higher temperatures induced oxidation to the sulfonyl group and substitution on the benzene ring. The change in NO₂ concentration of the exhaust gas with exposure time depended significantly on the exposure temperature. The improved model, which considered the NO₂ concentration distribution in the direction of the filter media thickness, reproduced these trends more accurately and could identify the gas–solid reaction between PPS and NO₂ gas as a homogeneous reaction at lower temperatures, and as a diffusion-controlled reaction in the product layer at higher temperatures successfully.